Papers in press

Influence of a CIDR after fixed-time AI on pregnancy rates and returns to estrus of nonpregnant cows

2008-11-07

We determined whether an ovulatory estrus could be resynchronized in previously synchronized, artificially inseminated (AI) nonpregnant cows without compromising pregnancy from the previous synchronized ovulation or to those inseminated at the resynchronized estrus. Ovulation was synchronized in 937 suckled beef cows at 6 locations using a CO-Synch + progesterone insert (controlled internal drug release; CIDR) protocol (a 100-µg injection of GnRH at the time of progesterone insert, followed in 7 d by a 25-mg injection of PGF₂at insert removal; at 60 h after PGF_2,cows received a fixed-time AI [TAI] plus a second injection of GnRH). After initial TAI, the cows were assigned randomly to 1 of 4 treatments: 1) untreated (control; n = 237); 2) progesterone insert at 5 d after TAI and removed 14 d after TAI (CIDR5-14; n = 234); 3) progesterone insert placed at 14 d after TAI and removed 21 d after TAI (CIDR14-21; n = 232); or 4) progesterone insert at 5d after TAI and removed 14d after TAI and then a new CIDR inserted at 14dand removed 21 d after TAI (CIDR5-21; n = 234). After TAI, cows were observed twice daily until 25 d after TAI for estrus and inseminated according to the AM-PM rule. Pregnancy was determined at 30 and 60 d after TAI to determine conception to the first and second AI. Pregnancy rates to TAI were similar for control (55%), CIDR5-14 (53%), CIDR14-21 (48%), and CIDR5-21 (53%). A greater (P < 0.05) proportion of nonpregnant cows were detected in estrus in the CIDR5-21 (76/110, 69%) and CIDR14-21 (77/120, 64%) treatments than in controls (44/106, 42%) and CIDR5-14 (39/109, 36%) cows. Although overall pregnancy rates after second AI service were similar, combined conception rates of treatments without a CIDR from d 14 to 21 (68.7% [57/83]; Control and CIDR5-14 treatments) were greater (P = 0.03) than those with a CIDR during that same interval (53.5% [82/153]; CIDR5-21 and CIDR14-21 treatments). We conclude that placement of a progesterone insert 5 d after a TAI did not compromise or enhance pregnancy rates to TAI; however, conception rates of nonpregnant cows inseminated after a detected estrus were compromised when resynchronized with a CIDR from d 5 or 14 until 21 d after TAI.

Porcine Sirt1 gene clone, expression pattern, and regulation by resveratrol

Shan, T., Wang, Y., Wu, T., Liu, C., Guo, J., Zhang, Y., Liu, J., Xu, Z. — 2008-11-07

Sirtuin1 (Sirt1) is a nicotinamide adenine dinucleotide (NAD)-dependent deacetylase that plays important roles in a variety of biological processes. In the current study, we examined the tissue-specific and the different expression pattern of porcine Sirt1 and the effect of resveratrol (RES) on expression of Sirt1 in porcine adipocytes. The full-length cDNA sequence of porcine Sirt1 was 4,024 bp (accession no: EU030283), with a 2,226-bp open reading frame encoding 742-AA protein (the predicated molecular mass of 80.9 kDa, accession no. ABS29571). Comparison of the deduced AA sequence with the AA sequences of human, dog, cattle, and mouse Sirt1 showed 82% to 92% similarity, respectively. Furthermore, the porcine Sirt1 was highly expressed in porcine brain, to a lesser degree in spleen and white adipose tissue, and lowest but detectable in liver. In s.c. adipose tissue and omental adipose tissue, the porcine Sirt1 mRNA in adult pigs was higher than that of young pigs (P < 0.01). In vitro, exposure of cultured adipocytes to 40 and 80 µM RES for 24 h increased mRNA levels of porcine Sirt1 by 47.86% (P < 0.01) and 91.04% (P < 0.01), respectively. Accordingly, lipid accumulation and NEFA release were decreased (P < 0.05), respectively. When treated with RES for 48 h, the mRNA level of porcine Sirt1 were increased by 103.84% (P < 0.01) and 148.79% (P < 0.01), respectively. Lipid accumulation was decreased and the NEFA release was increased (P < 0.05), respectively. These results provide some information needed for manipulating Sirt1 expression in regulating fat deposition in pigs.

Refined mapping of twinning rate QTL on bovine chromosome 5 and analysis of IGF1 as a positional candidate gene1,2

2008-11-07

Twinning in cattle is a complex trait that is associated with economic loss and health issues such as abortion, dystocia, and reduced calf survival. Twinning rate QTL have been previously detected on chromosome 5 in the North American Holstein and Norwegian dairy cattle populations and in a USDA herd selected for high twinning rate. In previous work with the North American Holstein population, the strongest evidence for a QTL was obtained from analysis of an extended, multiple generation family. Using additional animals, an increased density of SNP marker association tests and a combined linkage and linkage disequilibrium mapping method , the position of this QTL was refined in the North American Holstein population. Two sets of twinning rate predicted transmitting abilities estimated during 2 different time periods in the North American dairy cattle population were used to provide validation of results. A total of 106 SNPs and 3 microsatellites were used to scan the genomic region between 5 and 80 Mb on chromosome 5. Combined linkage-linkage disequilibrium analysis identified significant evidence for QTL within the 25 to 35 MB and 64 to 70 Mb regions of chromosome 5. IGF1 was examined as a positional candidate gene and a SNP in intron 2 of IGF1 was significantly associated with twinning rate using both data sets (P=0.003 and P=1.05x10^-6). Replication of this association in other cattle populations will be required to examine the extent of linkage disequilibrium with the underlying quantitative trait nucleotide across breeds.

Effects of dietary zilpaterol hydrochloride on feedlot performance and carcass characteristics of beef steers fed with and without monensin and tylosin

2008-11-07

A feedlot experiment was conducted under commercial conditions in the Texas Panhandle using 3,757 feedlot steers (average of 94 steers/pen) to evaluate the effects of feeding zilpaterol hydrochloride with or without monensin and tylosin on feedlot performance and carcass characteristics. The experiment was conducted using a randomized complete block design. Treatments were arranged as a 2 (no zilpaterol vs. zilpaterol) x 2 (monensin and tylosin withdrawn vs. monensin and tylosin fed during the final 35 d on feed) factorial. Steers were fed for a total of 161 to 167 d, and treatments were administered during the final 35 d cattle were on feed. When included in the diet, zilpaterol, monensin, and tylosin were supplemented at 8.3, 33.1, and 12.2 mg/kg (DM basis), respectively. Zilpaterol was included in the diet for 30 d at the end of the finishing period, and withdrawn from the diet for the last 5 or 6 d cattle were on feed. Cattle were harvested and carcass data collected. There were no zilpaterol x monensin/tylosin interactions (P > 0.12) for ADG or G:F. Feeding zilpaterol increased ADG (P < 0.001) by 0.20 kg and G:F (P < 0.001) by 0.029 kg/kg during the last 35 d on feed. Likewise, when feedlot variables were measured throughout the entire 161 to 167 d feeding trial, ADG (3.4%; P < 0.001) and G:F (3.9%; P < 0.001) were increased. Feeding zilpaterol increased (P < 0.001) dressing percent and HCW anddecreased (P < 0.001) total liver abscess rate compared with controls. In addition, zilpaterol increased (P < 0.001) LM area by an average of 8.0 cm². There was a zilpaterol x monensin/tylosin interaction (P = 0.03) for marbling score. Zilpaterol decreased (P < 0.001) marbling score regardless of monensin and tylosin treatment, although withdrawal of monensin and tylosin for 35 d decreased marbling to a greater extent (31 vs. 17 degrees). Zilpaterol decreased (i.e., improved; P < 0.001) calculated yield grade regardless of monensin and tylosin treatment, but feeding zilpaterol in combination with the withdrawal of monensin and tylosin for 35 d decreased calculated yield grade to a greater extent (0.49 vs. 0.29) compared with the zilpaterol, monensin, and tylosin combination treatment (zilpaterol x monensin/tylosin interaction, P = 0.03). Results suggest that monensin and tylosin can be withdrawn from the diet during the zilpaterol feeding period (final 35 d on feed) with minimal impact on animal performance, although feeding zilpaterol in combination with monensin and tylosin seemed to moderate effects on carcass quality.

Determination of nitrogen balance in goats fed a meal produced from hydrolyzed spent hen hard tissues

Freeman, S. R., Poore, M. H., Huntington, G. B., Middleton, T. F., Ferket, P. R. — 2008-11-07

In order to provide an economically viable and environmentally sound method for disposing of spent laying hens, we manufactured a proteinaceous meal from the hard tissue fraction of mechanically deboned laying hens (primarily feathers, bones, and connective tissue). We hydrolyzed the hard tissue and co-extruded it with soybean hulls to create a novel feather and bone meal (FBM) containing 94.2% DM, 23.1% CP, 54.5% NDF, and 7.3% fat (DM basis). We evaluated the FBM in supplements for meat goats in which it provided 0, 20, 40, or 60% of the N added to the supplement vs. a negative control supplement with no added N source. The remainder of the N was contributed by soybean meal (SBM). Supplementation of N resulted in greater DMI than the negative control (P = 0.005) and DMI changed quadratically (P = 0.11) as FBM increased in the supplement. Digestibility of DM was similar in all diets, including the negative control (P > 0.10). Fiber digestibility increased linearly as dietary inclusion of FBM increased (P = 0.04 for NDF, P = 0.05 for ADF), probably as a result of the soybean hulls in the FBM. Nitrogen digestibility declined linearly from 60.5% with 0% FBM to 55.6% with 60% FBM (P = 0.07), but N retention changed by a quadratic function as FBM replaced SBM (P = 0.06). Negative control goats had lower N digestibility (P < 0.001) and N retention (P = 0.008) than the N-supplemented goats. Feather and bone meal had a greater proportion of ruminally undegradable B₃ protein than SBM (23.1 vs. 0.3% of CP, respectively). Ruminal VFA and pH were unaffected by replacing SBM with FBM, but supplying no source of N in the concentrate resulted in reduced total VFA in ruminal fluid (P = 0.04). Ruminal ammonia level increased quadratically (P = 0.07) as FBM increased, reflecting increased intake, and it was much lower in unsupplemented goats (P < 0.001). Serum urea had less variation between 0 and 4 h after feeding in goats receiving 40 or 60% of added N as FBM in comparison to those receiving only SBM or 20% FBM. Feather and bone meal promoted a more stable rumen environment, possibly due to reduced rates of protein degradation within the rumen. A palatable byproduct meal for ruminants can be made from spent laying hen hard tissue, one that supports similar N metabolism to traditional protein sources.

Influence of different levels of concentrate and ruminally undegraded protein on digestive parameters in beef heifers

2008-11-07

This experiment evaluated the effect of 2 levels of diet concentrate (20 and 40% of DM) and 2 levels of ruminally undegraded protein (RUP: 25 and 40% of CP) on nutrient intake, total and partial apparent nutrient digestibility, microbial protein synthesis, and ruminal and physiological parameters. Eight Nellore heifers (233 ± 14 kg BW) fitted with ruminal, abomasal, and ileal cannulas were used. The animals were held at individual sheltered pens of approximately 15 m² and fed twice daily at 0800 and 1600 h for ad libitum intake. Heifers were allocated in two 4 x 4 Latin square designs, containing 8 heifers, 4 experimental periods, and 4 treatments in a 2 x 2 factorial arrangement. All statistical analyses were performed using PROC MIXED of SAS. Titanium dioxide (TiO₂) and chromic oxide (Cr₂O₃) were used to estimate digesta fluxes and fecal excretion. Purine derivative (PD) excretion and abomasal purine bases were used to estimate the microbial N (MN) synthesis. No significant interaction (P > 0.10) between dietary levels of RUP and concentrate was observed. There was no effect of treatment (P = 0.24) on DMI. Both markers led to the same estimates of fecal, abomasal, and ileal DM fluxes, and digestibilities of DM and individual nutrients. Ruminal pH was affected by sampling time (P < 0.001), but no interaction between treatment and sampling time was observed (P = 0.71). There was an interaction between treatment and sampling time (P < 0.001) for ruminal NH₃-N concentration. A linear decrease (P = 0.04) over sampling time was observed for the higher level of RUP, whereas a quadratic effect (P < 0.001) of sampling time was observed for the lower level of RUP. The higher level of dietary concentrate led to greater MN yield regardless the level of RUP. The MN yield and the efficiency of microbial yield estimated from urinary PD excretion produced greater (P < 0.01) values than those estimated by either TiO₂ or Cr₂O₃, whichdid not differ (P = 0.63) from each other. However, all methods yielded values that were within the range reported in the literature. In conclusion, no interactions between dietary levels of RUP and concentrate were observed for ruminal and digestive parameters. Neither RUP nor concentrate level affected DMI. Titanium dioxide showed to be similar to Cr₂O₃ as an external marker to measure digestibility and nutrient fluxes in cattle.

Effects of dietary uridine 5'-monophosphate on immune responses in newborn calves

2008-11-07

When compared to normal milk, bovine colostrum contains a large amount of uridine 5’-monophosphate (UMP) and its derivatives. In the present study, we carried out 2 experiments to determine the effects of dietary UMP (2 g/d) on the immune status of newborn calves. In Exp. 1, newborn Holstein bull calves were fed milk replacer alone (control group) or milk replacer supplemented with UMP (UMP group) from d 4 to 10 after birth. Increase in interferon- (IFN-) concentration by peripheral blood mononuclear cells (PBMC) on d 24 tended to be greater in the UMP group than in the control group (P = 0.06). The immunoglobulin A concentration of the ileal mucosa was greater in the UMP group than in the control group (P < 0.05), although there was no difference between groups in the jejunal mucosa. In Exp. 2, newborn Holstein bull calves were fed milk replacer alone (control group) and milk replacer supplemented with UMP (UMP group) from d 4 to 56 after birth. The proliferation of PBMC was greater in the UMP group than in the control group on d 14, 28, and 42 (P < 0.01). Increase in IFN- concentration by PBMC was greater in the UMP group than in the control group on d 28 and 42 (P < 0.05). From these results, we conclude that dietary UMP affects the immune responses of newborn calves.

Impact of ovariohysterectomy and food intake on body composition, physical activity, and adipose gene expression in cats

Belsito, K. R., Vester, B. M., Keel, T., Graves, T. K., Swanson, K. S. — 2008-11-07

The mechanisms contributing to weight gain following ovariohysterectomy in domestic cats are poorly understood. Moreover, the effects of food restriction to maintain BW following spaying have been poorly studied. Thus, our primary objective was to determine the effects of spaying and food restriction to maintain BW on adipose and skeletal muscle mRNA abundance and activity levels in cats. After a 4-wk baseline period (wk 0), 8 adult (~1.5 yr old) domestic shorthair cats were spayed and fed to maintain BW for 12 wk. After 12 wk, cats were fed ad libitum for an additional 12 wk. Body composition was determined, activity levels were measured, and adipose and muscle biopsies were collected at wk 0, 12, and 24. Fasted blood samples were collected at wk 0, 6, 12, 18, and 24. To maintain BW post-spay, food intake was decreased (P < 0.05) by 30%. During this phase, mRNA abundance of adipose tissue lipoprotein lipase and leptin was decreased (P < 0.05) by approximately 2-fold and 4-fold, respectively. Interleukin-6 mRNA, however, was increased (P < 0.05) 2-fold. Physical activity was decreased (P < 0.05) by wk 12, most dramatically during the dark period (approximately 20% of baseline activity). During ad libitum feeding (wk 12 to wk 24), food intake, BW, body fat percentage, and total fat mass were greatly increased (P < 0.05). Compared to wk 0, circulating leptin concentrations tended to increase (P < 0.10) by wk 18 and 24 (4.45 vs. 10.02 and 9.14 ng/mL, respectively), while glucose (91 vs. 162 mg/dL) and triacylglyceride (30 vs. 48 mg/dL) concentrations were increased (P < 0.05) by wk 24. Adipose tissue lipoprotein lipase, hormone sensitive lipase, and adiponectin mRNA were decreased (P < 0.05) at wk 24. Adipose interleukin-6 mRNA was increased (P < 0.05) at 24 wk. Physical activity was further decreased (P < 0.05) by wk 24, during the light (60% of baseline) and dark (33% of baseline) periods. In summary, spaying and food restriction impacts physical activity levels and several genes associated with lipid metabolism (decreased lipoprotein lipase), food intake (decreased leptin expression), and insulin insensitivity (increased interleukin-6). By identifying these changes, targets for nutritional intervention or lifestyle management have been identified that may curb the risk of obesity and related disorders in spayed cats.

Cell Biology Symposium: The Role of MicroRNA in Cell Function

Cupp, A. S., Matthews, J., Huff-Lonergan, E., Spurlock, D. M., McLean, D. — 2008-11-07

A new symposium was introduced at the Centennial Meeting of the American Society of Animal Science (ASAS) meeting during the joint annual meeting of ASAS and the American Dairy Science Association in Indianapolis, Indiana, on July 8, 2008. The purpose of the Cell Biology Symposium is to bring scientists with cutting edge basic research on a particular theme to the ASAS meeting. In the future we hope to expand this symposium by including a poster session for ASAS participants and invited speakers to interact. This year the theme of the Cell Biology Symposium was "The Role of MicroRNA in Cell Function". Four speakers delved into the basic function of microRNA, their role in hepatic cell function, regulation of muscle characteristics, and their role in female reproduction.

Characterization of Feed Efficiency Traits and Relationships with Feeding Behavior and Ultrasound Carcass Traits in Growing Bulls

2008-11-07

Objectives of this study were to characterize feed efficiency traits and to examine phenotypic correlations with performance and feeding behavior traits, and ultrasound measurements of carcass composition in growing bulls. Individual DMI and feeding behavior traits were measured in Angus bulls (n = 341; initial BW = 371.1 ± 50.8 kg) fed a corn silage-based diet (ME = 2.77 Mcal/kg DM) for 84 d in Trials 1 and 2 and for 70 d in Trials 3 and 4 using a GrowSafe feeding system. Meal duration (min/d) and meal frequency (events/d) were calculated for each bull from feeding behavior recorded by the GrowSafe system. Ultrasound measures of carcass 12^th rib fat thickness (BF) and longissimus muscle area (LMA) were obtained at the start and end of each trial. Residual feed intake (RFIp) was computed from linear regression of DMI on ADG and mid-test BW^0.75 with trial, trial by ADG and trial by mid-test BW^0.75 as random effects (base model). Overall ADG, DMI and RFIp were 1.44 (SD = 0.29), 9.46 (SD = 1.31), and 0.00 (SD = 0.78) kg/d, respectively. Stepwise regression analysis revealed that inclusion of gain in BF and LMA in the base model increased R² (0.76 vs. 0.78), and accounted for 9% of the variation in DMI not explained by MBW and ADG (RFIp). Residual feed intake (RFIp) and carcass-adjusted RFI (RFIc) were moderately correlated with DMI (0.60 and 0.55, respectively) and FCR (0.49 and 0.45, respectively), and strongly correlated with partial efficiency of growth (PEG; -0.84 and -0.78, respectively), but not with ADG or MBW. Gain in BF was weakly correlated with RFIp (0.30), FCR (-0.15), and PEG (-0.11), but not RFIc. Gain in LMA was weakly correlated with RFIp (0.17) and FCR (-0.19), but not PEG or RFIc. The Spearman rank correlation between RFIp and RFIc was high (0.91). Meal duration (0.41), head down duration (0.38), and meal frequency (0.26) were correlated with RFIp, and accounted for 35% of the variation in DMI not explained by MBW, ADG and ultrasound traits (RFIc). These results suggest that adjusting RFI for carcass composition will facilitate selection to reduce feed intake in cattle without affecting rate or composition of gain.

Cellular regulation of bovine intramuscular adipose tissue development and composition

Smith, S. B., Kawachi, H., Choi, C. B., Choi, C. W., Wu, G., Sawyer, J. E. — 2008-11-07

It is well documented that grain feeding stimulates adipogenesis in beef cattle, whereas pasture feeding depresses the development of adipose tissues, including intramuscular (i.m.) adipose tissue. Additionally, production practices that depress adipocyte differentiation also limit the synthesis of monounsaturated fatty acids (MUFA). Marbling scores and MUFA increase in parallel, indicating that stearoyl-CoA desaturase (SCD) gene expression is closely associated with and(or) necessary for differentiation of marbling adipocytes. Similarly, marbling scores and fatty acid indices of SCD activity are depressed in response to dietary vitamin A restriction. In bovine preadipocytes, vitamins A and D both decrease glycerol-3-phosphate dehydrogenase (GPDH) activity, an index of adipocyte differentiation, whereas incubation of bovine preadipocytes with L-ascorbic acid-2-phosphate increases GPDH activity. Exposing bovine preadipocytes to zinc also stimulates adipogenesis, putatively by inhibiting nitric oxide (NO) production. However, incubation of bovine preadipocytes with arginine, a biological precursor of NO, strongly promotes differentiation in concert with increased SCD expression. This indicates that the effect of either arginine or zinc on adipogenesis is independent of NO synthesis in bovine preadipocytes. Enhanced expression of SCD is associated with a greater accumulation of MUFA both in bovine preadipocyte cultures and during development in growing steers. In bovine preadipocytes, trans-10, cis-12 conjugated linoleic acid (t10,c12 CLA) strongly depresses adipocyte differentiation and SCD gene expression, thereby reducing MUFA concentrations. The bovine preadipocyte culture studies indicate that any production practice that elevates vitamins A or D or t10,c12 CLA in bovine adipose tissue will reduce i.m. adipose tissue development. Conversely, supplementation with vitamin C or zinc may promote the development of i.m. adipose tissue.

Winter grazing system and supplementation during late gestation influence performance of beef cows and steer progeny

Larson, D. M., Martin, J. L., Adams, D. C., Funston, R. N. — 2008-11-07

A 2 x 2 factorial study evaluated effects of cow wintering system and last trimester CP supplementation on performance of beef cows and steer progeny over a 3 yr period. Pregnant composite cows (Red Angus x Simmental) grazed either winter range (WR; n = 4/yr) or corn residue (CR; n = 4/yr) during winter and within grazing treatment received 0.45 kg/d (DM) 28% CP cubes (PS; n = 4/yr) or no supplement (NS; n = 4/yr). Offspring steer calves entered the feedlot 14 d post-weaning and were harvested 222 d later. Pre-calving BW was greater (P = 0.02) for PS than NS cows grazing WR, whereas pre-calving BCS was greater (P < 0.001) for cows grazing CR compared to WR. Calf birth BW was greater (P = 0.02) for CR than WR and tended to be greater (P = 0.11) for PS than NS cows. Pre-breeding BW and BCS were greater (P ≤ 0.001) for CR than WR cows and PS than NS (P = 0.006) cows. At weaning, CR cows were heavier (P < 0.001) than WR cows but had similar BCS (P = 0.74). Cow weaning BW and BCS were not affected (P > 0.32) by PS. Calf weaning BW was lower (P = 0.01) for calves from NS cows grazing WR compared to all other treatments. Pregnancy rate was unaffected by treatment (P > 0.39). Steer ADG, 12^th rib fat, yield grade and LM area (P > 0.10) were similar among all treatments. However, final BW and HCW (P = 0.02) were greater for steers from PS-WR than NS-WR cows. Compared to steers from NS cows, steers from PS cows had greater marbling scores (P = 0.004) and a greater (P = 0.04) proportion graded USDA Choice or greater. Protein supplementation of dams increased the value of calves at weaning (P = 0.03) and of steers at harvest regardless of winter grazing treatment (P = 0.005). Calf birth and weaning BW were increased by grazing CR during the winter. Calf weaning BW was increased by PS of the dam if the dam grazed WR. Compared to steers from NS cows, steer progeny from PS cows had a greater quality grade with no (P = 0.26) affect on yield grade. These data support a late gestation dam nutrition effect on calf production via fetal programming.

Influence of toxic endophyte-infected fescue on sperm characteristics and endocrine factors of yearling Brahman-influenced bulls

2008-11-07

Sixteen (mean age = 1.1 ± 0.1 yr; mean BW = 478 ± 34 kg) Brahman-influenced bulls were used to determine the influence of fescue type on sperm characteristics and serum concentrations of prolactin, cortisol, and testosterone. Bulls were blocked by BW, scrotal circumference (SC), and pregrazing sperm characteristics and randomly assigned to graze either toxic endophyte-infected (EI; 4 bulls/pasture; 2 pastures) or novel endophyte-infected (NE; 4 bulls/pasture; 2 pastures) tall fescue for 121 d. Semen was collected by electroejaculation, and SC was measured and blood samples collected monthly. Sperm were evaluated for motility and morphology with an integrated visual optical system. Overall mean concentration of prolactin was decreased more (P < 0.01) in EI bulls than NE bulls from May to August. Scrotal circumference was not affected by fescue type (P = 0.58); overall SC averaged 36.7 ± 2.3 cm. Percentage of live sperm was not different (P = 0.24) between NE bulls (80%) than EI bulls (67%) in July and August. Bulls grazing NE fescue had more (P < 0.06) motile sperm than EI bulls in July and August. Percentages of progressive (57 vs. 38%, NE and EI, respectively; P < 0.06) and rapid (67 vs. 46%, NE and EI, respectively; P = 0.04) sperm were greater from bulls grazing NE than EI bulls in both July and August. Average velocity of the smoothed sperm path and progressive velocity in a straight line from the beginning to the end of the sperm track were slower (P < 0.09) in EI bulls than NE bulls and were slower (P = 0.04) in August compared with July. Mean width of head oscillation as the sperm swims was less (P < 0.06) in August than July. Concentrations of cortisol and testosterone were not (P > 0.10) influenced by fescue type. Semen from bulls grazing EI had reduced motility and morphology than bulls grazing NE. Detrimental effects of toxic fescue may not be mediated by cortisol and (or) testosterone. Semen quality of bulls grazing toxic EI tall fescue was decreased with increased maximum ambient temperatures.

Effects of sodium chloride and fat supplementation on finishing steers exposed to hot and cold conditions

Gaughan, J. B., Mader, T. L. — 2008-11-07

Three studies were conducted to evaluate the effects of supplemental fat and salt (NaCl) on DMI, water intake (DWI), body temperature, and respiration rate (RR) in Bos taurus beef cattle. In Exp. 1 and Exp. 2, whole soybeans (SB) were used as the supplemental fat source. In Exp. 3, palm kernel meal and tallow were used. Exp. 1 (winter) and Exp. 2 (summer) were undertaken in an outside feedlot. Exp. 3 was conducted in a controlled climate facility (mean ambient temperature = 29.9^oC). In Exp. 1, 3 diets (i) control, (ii) salt: control + 1% NaCl, and (iii) salt-SB: control + 5% SB + 1% NaCl were fed to 144 cattle (BW = 327.7 kg) utilizing a replicated 3 x 3 Latin square design. In Exp. 2, 168 steers (BW = 334.1 kg) were used. In Exp. 2, the same dietary treatments were utilized as Exp. 1 plus a 5% SB dietary treatment were included in an incomplete 3 x 4 Latin square design. In Exp. 3, 3 diets (i) control, (ii) salt: control + 0.92% NaCl, and (iii) salt-fat: control + 3.2% added fat + 0.92% NaCl were fed to 12 steers (BW = 602 kg) in a replicated Latin square design. In Exp. 1, cattle fed salt-SB had elevated (P < 0.05) tympanic temperature (TT; 38.83^oC) compared to cattle fed control (38.56^oC) or salt (38.50^oC). In Exp. 2, salt and salt-SB treatments had lower (P < 0.05) DMI and greater (P < 0.05) DWI than control and SB treatments. Cattle fed the salt-SB diet had the highest (P < 0.05) TT (38.89^oC). Those fed only the salt or only the SB diets had the lowest (P < 0.05) TT at 38.72^oC and 38.78^oC, respectively. Under hot conditions (Exp. 3), DMI of salt fed and salt-fat fed steers fell by approximately 40% vs. only 24% for the control cattle. During hot conditions DWI was greatest (P < 0.05) for the salt-fat steers. These steers also had the highest (P < 0.05) mean rectal temperature (40.03 ± 0.1°C) and RR (112.7 ± 1.7 breaths/min). The RR of control steers was the lowest (P < 0.05; 98.3 ± 1.7 breaths/min). Although added salt plus fat lowered DMI under hot conditions, these data suggest switching to diets containing the combination of added salt and fat elevates body temperature, which would be a detriment in the summer but a benefit to the animal during winter. Nevertheless, adding salt plus fat to diets resulted in increased DWI under hot conditions. Diet ingredients or combination of ingredients that can be used to regulate DMI may be useful to limit large increases in DMI during adverse weather events.

Influence of equalizing the gross composition of milk replacer to that of whole milk on the performance of Holstein calves

2008-11-07

This study compared the performance of female Holstein calves fed either whole milk (WM) or milk replacer (MR) having similar gross composition to WM. Calves (n = 20) were separated from their motherswithin 2 h of birth, weighed, moved into individual pens andfed colostrum (10% of their BW over two feedings daily) for the first 3 d. Calves were alternately assigned to either WM (n=10) or MR (n=10) feeding and were fed using mobile plastic bottles. At each feeding, diluted MR was prepared in buckets by mixing 0.143 kg of MR powder (as is basis) in 1L of lukewarm water. Calves on both treatments were fed (1.8 L / feeding) for 4 times daily for the first 25 d of age. Feeding frequency was reduced to 3 times daily for next 5 d; then to 2 times daily for next 14 d and then to once daily during the last 5 d of pre-weaning period. Feed intake, growth and health parameters were monitored until calves were 70 d of age. Mean daily consumption of WM and MR was similar in both treatment groups (P = 0.74). Initial BW of calves fed either WM or MR was similar (42.1 ±3.3 vs. 41.9 ±2.9 kg, respectively; P = 0.83). Calves fed WM or MR daily consumed similar amounts of calf starter (1019 vs. 1056 g, respectively; P = 0.32), hay (121.5 vs 126.3 g, respectively; P = 0.30), and water (5.2 vs. 5.0 kg, respectively; P = 0.54). At weaning (d 49) and post-weaning (d 70), BW was greater (P = 0.03 and P = 0.02, respectively) in calves fed WM than in those fed MR. Mean DM intake from both solid and liquid feeds was not affected by the treatments during pre-weaning (P = 0.21) and post-weaning (P = 0.16) periods. Gain efficiency during pre-weaning and overall was better (P = 0.001 and P = 0.002, respectively) in calves fed WM than in those fed MR. Health (days scoured, rectal temperature, respiratoryscore, and general appearance score) and serum chemistry parameters (glucose, total protein, urea N, non-esterified fatty acids, and creatinine) in calves were not affected (P ≥ 0.12 and P ≥ 0.12, respectively) by the treatments. Even though composition of the MR and WM was similar, growth was still greater in calves fed WM. Calves fed WM consumed similar amounts of DM and were heavier than those fed MR probably because of better bio-availability (digestion and assimilation) of nutrients and availability of some unknown growth factors from WM.

Consequences of selection for improving production traits on the frequency of deleterious alleles for fitness

Kearney, J. F., Navarro, P., Haley, C. S., Villanueva, B. — 2008-11-07

In this study the effect of artificial selection on BLUP estimated breeding values for production traits on the allele frequencies of a pleiotropic QTL (quantitative trait locus) affecting both production and disease susceptibility was investigated. Stochastic simulations were used to model artificial selection on a production trait that is controlled, in part, by a biallelic QTL that also controls susceptibility to disease. The QTL allele increasing production also increased susceptibility to disease. Different modes of action and proportions of variation accounted for by the QTL were assessed for the production trait. The main results indicated that alleles that confer susceptibility to the disease can be maintained in the population over a long period of time, depending on the mode of action of the QTL. In addition, the results of the study indicate that, under various conditions, it is possible to find pleiotropic QTL that control 2 traits despite these traits appearing to be uncorrelated. Therefore, in practice, an estimate of the genetic correlation between 2 traits may be misleading when the presence of such a QTL exists. The results of this study have implications for breeding programs. For example, if a pleiotropic QTL exists that favors heterozygotes for a production trait, it would be very difficult to remove disease susceptibility alleles via traditional selection methods.

Post-natal piglet husbandry practices and well-being: The effects of alternative techniques delivered separately

2008-11-07

The aim of this study was to evaluate stress responses evoked by 2 alternative methods for performing the following processing procedures: 1) teeth resection (TR) – clip vs. grind; 2) tail-docking (TD) – cold vs. hot-clip; 3) identification (ID) – ear notch vs. tag; 4) iron administration (FE) – inject vs. oral; 5) castration (CA) – cords cut vs. torn. Eight to 10 litters of eight, 2- and 3-d-old piglets were assigned to each procedure. Within each litter, 2 piglets were assigned to 1 of 4 possible procedures: the 2 alternative methods, a sham procedure, and a sham procedure plus blood sampling. Blood was sampled before processing and at 45 min, 4 h, 48 h, 1 wk, and 2 wk post-procedure and assayed for cortisol and β-endorphin. Procedures were video-taped and analyzed to evaluate the time taken to perform the procedure and the number of squeals, grunts and escape attempts. Vocalizations were analyzed to determine mean and peak frequencies and duration. Piglets were weighed before the procedure and at 24 h, 48 h, 1 wk, and 2 wk afterwards. Lesions were scored on a 0 to 5 scale on ID, TD and CA pigs at 24 h, 1 wk, and 2 wk post-procedure. For TR, grinding took longer than clipping and resulted in greater cortisol concentration overall, poorer growth rates and longer vocalizations compared to control treatment pigs (P < 0.05). For TD, hot clipping took longer and hot-clipped piglets grew slower than cold-clipped piglets (P < 0.05). Hot clipping also resulted in longer and higher frequency squealing than control pigs (P < 0.01). For ID, ear notching took longer than tagging and ear-notched piglets had worse wound scores than tagged piglets (P < 0.05). Cortisol concentrations at 4 h also tended to be greater for notched piglets (P < 0.10). Ear notching evoked calls with higher peak frequency than control treatments. For FE, oral delivery took numerically longer than injecting, but there were no significant differences between injecting and oral delivery in any of the measures. For CA, tearing took longer than cutting the cords (P < 0.05) but β-endorphin concentrations at 45 min post-procedure were greater for cut piglets. Using measures of behavior, physiology and productivity, the responses to TR, TD and ID can be shown to be altered by method of procedure whereas responses to FE and CA did not differ. The time taken to carry out the procedure would appear to be an important factor in the strength of the stress response.

Effects of social interactions on empirical responses to selection for average daily gain of boars

Chen, C. Y., Johnson, R. K., Newman, S., Kachman, S. D., Van Vleck, L. D. — 2008-11-07

Effects of social interactions on responses to selection for ADG were examined with records of 9,720 boars from dam lines (1 and 2) and sire lines (3 and 4) provided by Pig Improvement Company. Each line was analyzed separately. Pens contained 15 boars. Gains (ADG) were measured from about 71 to 161 d of age and weight from 31 to 120 kg. Models included fixed effects of contemporary groups and initial test age as a covariate, and random direct genetic (d), social genetic (c), social environmental (ce), and litter (lt) effects. Estimates of direct heritability with Model 1 (the full model with d, c, ce, and lt) were 0.21, 0.28, 0.13, and 0.15 for lines 1 to 4. Estimates of heritability of social effects were near zero. Estimates of total heritable variance were 55, 52, 38, and 96% of phenotypic variance for lines 1 through 4. Empirical responses to selection with Model 1 were calculated using the parameter estimates from Model 1. For response of 1 genetic SD for both components (d and c), the proportions of expected total gain due to social effects (with economic weights of 1 and pen size-1=14) were 54, 28, 65, and 65% for the 4 lines. Genetic superiorities of the top 10% of boars were calculated for boars ranked using reduced models, but with EBV calculated using the full model (Model 1). Average total breeding values (ETBV=EBV_d+14EBV_c) for the top 10% of boars selected with Model 1 were 74.08, 94.26, 31.79, and 92.88 g for lines 1 through 4, respectively. For rankings based on Model 2 (d, ce, and lt), but EBV calculated with Model 1, average total breeding values for the top 10% were 68.15, 94.03, 7.33, and 84.72 g with empirical correlated responses for genetic social effects from selection for direct effects of 0.93, 1.89, -2.19, and 3.52 g for lines 1 to 4.

Omega-3 fatty acids in the gravid pig uterus as affected by maternal supplementation with omega-3 fatty acids

Brazle, A. E., Johnson, B. J., Webel, S. K., Rathbun, T. J., Davis, D. L. — 2008-11-07

Two experiments evaluated the ability of maternal fatty acid supplementation to alter conceptus and endometrial fatty acid composition. In Exp. 1, treatments were control, corn-soybean meal diet; flax, control diet plus ground flax (3.75% of diet); and protected fatty acids (PFA), control plus a protected fish oil source rich in n-3 polyunsaturated fatty acids (Gromega, 1.5% of diet). Supplements replaced equal parts of corn and soybean meal. When gilts reached 170 d of age, PG600 (PMSG and hCG) was injected to induce puberty and dietary treatments (n = 8/treatment) initiated. When detected in estrus, gilts were artificially inseminated. On d 40 to 43 of gestation, 7 control, 8 PFA, and 5 Flax gilts were pregnant and were slaughtered. Compared to control, Flax tended to increase eicosapentaenoic acid (EPA: C20:5n-3) in fetuses (0.14 vs 0.25 + 0.03 mg/g dry tissue; P = 0.055) while gilts receiving PFA had more (P < 0.05) docosahexaenoic acid (DHA: C22:6n-3) in their fetuses (5.23 vs 4.04 + 0.078 mg/g) as compared to controls. Both flax and PFA diets increased (P < 0.05) DHA (0.60, 0.82, and 0.85 + 0.078 mg/g for control, flax and PFA, respectively) in the chorioallantois. In the endometrium, EPA and docosapentaenoic acid (DPA: C22:5n-3) were increased by flax (P < 0.001; P < 0.05); whereas, gilts receiving PFA had increased DHA (P < 0.001). Flax selectively increased EPA and PFA selectively increased DHA in the fetus and endometrium. In Exp. 2, gilts were fed diets containing PFA (1.5%) or control beginning at approximately 170 of age (n = 13/treatment). A blood sample was collected after 30 d of treatment, and gilts were artificially inseminated when they were approximately 205 d old. Conceptus and endometrial samples were collected on d 11 to 19 of pregnancy. Plasma samples indicated that PFA increased (P < 0.005) circulating concentrations of EPA and DHA. Endometrial EPA was increased (P < 0.001) for PFA gilts. In extraembryonic tissues, PFA more than doubled (P < 0.001) EPA (0.13 vs 0.32 + 0.013 mg/g) and DHA (0.39 vs 0.85 +0.05 mg/g). In embryonic tissue on d 19, DHA was increased (P < 0.05) by PFA (0.20 vs 0.30 + 0.023mg/g). Supplementing n-3 PUFA, beginning 30 d before breeding, affects endometrial, conceptus and fetal fatty acid composition in early pregnancy. Dynamic day effects in fatty acid composition indicate this may be a critical period for maternal fatty acid resources to affect conceptus development and survival.

Effects of dietary selenium supply and timing of nutrient restriction during gestation on maternal growth and body composition of pregnant adolescent ewes

2008-11-07

The objectives were to examine effects of dietary Se supplementation and nutrient restriction during defined periods of gestation on maternal adaptations to pregnancy in primigravid sheep. Sixty-four pregnant, Western Whiteface ewe lambs were assigned to treatments in a 2 x 4 factorial design. Treatments were dietary Se [adequate Se (ASe; 3.05 µg/kg BW) vs. high Se (HSe; 70.4 µg/kg BW)] fed as Se-enriched yeast, and plane of nutrition [control (C; 100% of NRC requirements) vs. restricted (R; 60% of NRC requirements]. Selenium treatments were fed throughout gestation. Plane of nutrition treatments were applied during mid (d 50 to 90) and late gestation (d 90 to 130), which resulted in 4 distinct plane of nutrition treatments (CC, RC, CR, and RR). All of the pregnant ewes were necropsied on d 132 ± 0.9 of gestation (length of gestation 145 d). Nutrient restriction treatments decreased ewe ADG and G:F, as a result, RC and CR ewes had similar BW and maternal BW (MBW) at necropsy, whereas RR ewes were lighter than RC and CR ewes. From d 90 to 130, the HSe-CC ewes had greater ADG (Se x nutrition; P = 0.05) than did ASe-CC ewes, whereas ADG and G:F (Se x nutrition; P = 0.08) were less for HSe-RR ewes compared with ASe-RR ewes. The CR and RR treatments decreased total gravid uterus weight (P = 0.01) as well as fetal weight (P = 0.02) compared with RC and CC. High Se decreased total (g; P = 0.09) and relative heart mass (g/kg MBW; P = 0.10), but increased total and relative mass of liver (P ≤ 0.05) and perirenal fat (P ≤ 0.06) compared with ASe. Total stomach complex mass was decreased (P < 0.01) by all the nutrient restriction treatments, but was reduced to a greater extent in CR and RR compared with RC. Total small intestine mass was similar between RC and CC ewes, but was markedly reduced (P < 0.01) in CR and RR ewes. The mass of the stomach complex and the small and large intestine relative to MBW was greater (P = 0.01) for RC than for CR ewes. High Se decreased jejunal DNA concentration (P = 0.07), total jejunal cell number (P = 0.03), and total proliferating jejunal cell number (P = 0.05) compared with ASe. These data indicate that high dietary Se affected whole-body and organ growth of pregnant ewes, but the results differed depending on the plane of nutrition. In addition, the timing and duration of nutrient restriction relative to stage of pregnancy affected visceral organ mass in a markedly different fashion.

Effect of solid feed on energy and protein utilization in milk-fed veal calves

Labussiere, E., Dubois, S., van Milgen, J., Bertrand, G., Noblet, J. — 2008-11-07

Little knowledge on the digestive and metabolic utilization of solid feed in veal calves is available. The objectives of the study were to determine the effects of 2 solid feeds offered at 2 feeding levels (FL90 and FL105) in addition to a milk replacer on heat production (HP) and protein and fat deposition in veal calves. Sixteen calves (148.0 ± 3.7 kg) received milk replacer (75% of a reference DE allowance, FL75) and solid feeds that consisted of corn grain and pelleted hydrolyzed wheat gluten without (C) or with (CS) chopped wheat straw. The solid feed supply provided 15 or 30% of the reference DE allowance to achieve FL90 or FL105, resulting in 4 treatments: C90, CS90, C105 and CS105. A fifth treatment consisted of using the milk replacer alone at FL90 (treatment M90) and was measured in 4 other calves. All calves were kept individually for 7 d in a respiration chamber to estimate energy and N balances and fasting HP. The digestibility coefficients of DM, OM, GE, and major nutrients were at least 94% for M90 and they decreased when solid feed was added (P < 0.05). Methane production was negligible in M90 calves and increased when solid feed was given (ranging 8 to 23 L/d between C90 and CS105, P < 0.01), indicative of ruminal fermentation. The provision of increasing amounts of solid feed decreased urinary energy in connection with a tendency (P = 0.09) for a reduction of urinary glucose excretion. The metabolizability of DE was greater with the milk replacer (95.6%) and decreased when straw was added (P < 0.01). Neither C90 or CS90 affected HP and total energy retention (P > 0.05). Dietary treatment had no effect (P > 0.05) on activity HP (53 kJ/kg BW^0.85 daily), but it did affect thermic effect of feeding; efficiency of utilizing ME for maintenance and growth was greatest for the M90 calves (84.5%, P = 0.02). Fasting HP tended (P = 0.09) to increase at the highest FL (308 vs. 298 kJ/kg BW^0.85 daily). Maintenance ME requirement increased (P = 0.04) from 364 to 382 kJ/kg BW^0.85 daily when feeding level increased (P = 0.04) but was not affected by ingestion of solid feed. The provision of solid feed to veal calves was associated with a reduced efficiency of N retention (P = 0.04), and energy retained as protein tended to decrease (P = 0.08), probably as a result of an imbalanced AA supply of the solid feeds. The data were used to calculate the energy contents of solid feed. The utilization of energy from solid feed differed from that of milk replacer.

Molecular basis for Residual Feed Intake in beef cattle

Moore, S. S., Mujibi, F. D., Sherman, E. L. — 2008-10-24

Feed provision is one of the highest costs of beef production and, with the rising costs of feed, will remain so for the foreseeable future. Improvement in efficiency has the potential to not only increase profits for cattle producers, but also to decrease the environmental footprint of beef cattle production. Both are important in addressing the challenges of increasing feed costs and land pressure. Residual feed intake (RFI) has increasingly become the measure of choice when evaluating feed efficiency in beef cattle, especially because it is independent of growth and body weight. The main inhibitor to adoption of RFI remains the cost and technical difficulty in measuring the trait. This makes RFI a prime candidate for marker assisted selection because the trait is moderately heritable and DNA or other predictive markers could be used in selection schemes. Although multiple markers have been described over a number of studies, no major gene affecting RFI has been found. However, a combination of genetic markers, when examined jointly, can explain a large proportion of the genetic variation. Two main barriers remain before full adoption of markers for genetic evaluation and marker assisted selection can be implemented. First, the genetic interaction of genes affecting RFI on other traits is, as yet, not fully understood. Second the numbers of animals with high quality estimates of RFI remains small. However, current developments indicate that these challenges will soon be overcome.

Effect of protein supplementation on expression and distribution of urea transporter-B in lambs fed low-quality forage

2008-10-24

Two experiments were conducted to determine the effects of ruminal protein degradability, supplementation frequency, and increasing dietary protein on the expression and distribution of urea transporter-B (UT-B) in lambs fed low-quality forage (mature crested wheatgrass hay; 4.2 to 4.7% CP). In Experiment 1, 15 Dorset wether lambs (initial BW = 45.8 ± 1.3 kg) were blocked by initial BW and assigned to 1 of 3 treatments within a randomized complete block design for 28 d, with supplements fed to achieve 7, 10, or 13% total dietary CP. In Experiment 2, 13 Dorset wether lambs (initial BW = 34 ± 4 kg) were used in a completely randomized designed experiment and given 1 of 4 isonitrogenous supplements: 1) ruminally degradable protein (RDP) fed daily (n = 3), 2) RDP fed on alternate days (n = 3), 3) ruminally undegradable protein (RUP) fed on alternate days (n = 3), or 4) a 50:50 mixture of RDP and RUP fed on alternate days (n = 4) for 18 d. Alternate-day treatments were fed at twice that of daily supplementation. On the last day of both experiments, lambs were euthanized and samples taken for Western blot analyses for UT-B. Immunoblotting using a rabbit polyclonal antibody to UT-B confirmed the presence of distinct 32 kDa (consistent with a non-glycosylated UT-B protein) and 47 kDa (probable N-glycosylated form of UT-B) protein bands in all 9 tissues analyzed. In both experiments, the liver, dorsal rumen, reticulum, and ventral rumen displayed strong bands at 32 kDa and lighter bands at 47 kDa, whereas the cecum, large colon, spiral colon, and parotid salivary gland displayed slight 32 kDa bands and stronger, more visible bands at 47 kDa. Both protein bands were apparent in the kidney at similar visual intensities in Experiment 1, whereas the relative intensities of the 2 UT-B bands in the kidney were variable, and appeared somewhat reciprocal among animals. Although the abundance of the 47 kDa UT-B band in the ventral rumen was greater (P = 0.03) in lambs fed RDP daily in Experiment 2, no other treatment differences (P ≥ 0.15 to 0.99) in the abundance of the 32 or 47 kDa UT-B proteins within tissues were observed in either experiment. Although protein supplementation strategy had little effect on UT-B expression in tissues other than the ventral rumen, differences in the degree of glycosylation of UT-B across tissues may provide insight into its regulation.

Immune Components of Bovine Colostrum and Milk

Stelwagen, K., Carpenter, E., Haigh, B., Hodgkinson, A., Wheeler, T. T. — 2008-10-24

Colostrum and milk provide a complete diet for the neonate. In ruminants, colostrum is also the sole source of initial acquired immunity for the offspring. Milk, therefore, plays an important role in mammalian host defense. In colostrum, the level of immunoglobulins (Ig) is particularly high, with IgG being the major Ig class present in ruminant milk, in contrast to IgA being the major Ig present in human milk. Immunoglobulins are transported into mammary secretions via specialized receptors. In addition to immunoglobulins, both colostrum and milk contain viable cells, including neutrophils and macrophages, which secrete a range of immune-related components into milk. These include cytokines and antimicrobial proteins and peptides, such as lactoferrin, defensins, and cathelicidins. Mammary epithelial cells themselves also contribute to host defense through the secretion of a range of innate immune effector molecules. A detailed understanding of these proteins and peptides offers great potential to ‘add value’ to the dairy industry. This is demonstrated by the wide-ranging commercial applications of lactoferrin derived from bovine milk. Knowledge of the immune function of milk, in particular how the gland responds to pathogens, can be used to boost the levels of immune factors in milk through farm management practices and vaccination protocols. The latter approach is currently being used to maximize yields of bovine milk-derived IgA directed at specific antigens for therapeutic and prophylactic use. Increasingly sophisticated proteomics technologies are being applied to identify and characterize the function of the minor components of milk. An overview is presented of the immune factors in colostrum and milk as well as the results of research aimed at realizing this untapped value in milk.

Evaluation of the NRC (1996) dry matter intake prediction equations and relationships between intake and performance by feedlot cattle

McMeniman, J. P., Defoor, P. J., Galyean, M. L. — 2008-10-24

Intake prediction equations of NRC (1996) based on initial BW and dietary NEm concentration were evaluated with a commercial feedlot database consisting of 3,363 pen means collected from 3 feedlots over a 4-yr period. The DMI predicted by NRC (1996) equations had significant (P < 0.01) mean and linear biases across the range of observed DMI in the database. In general, DMI was over predicted by the NRC (1996) equations. Adjustment of the NEm-based prediction by use of a 12% increase in NEm concentration and a 4% decrease in predicted DMI associated with the feeding of monensin decreased bias. Dry matter intake predicted by the NEm-based monensin-adjusted, NEm-based, and initial BW equations explained 67, 66, and 64% of the variation in observed DMI, respectively. Relationships between ADG and G:F with DMI as a percentage of BW and NEg intake also were examined in the same data set. Across the wide range of average shrunk BW in the database (334.4 to 548.0 kg), ADG was positively related to DMI as a percentage of BW (P < 0.01); however, this relationship was not strong (r² = 0.17). Likewise, G:F showed little relationship with DMI as a percentage of BW (P < 0.01; r²= 0.05). By accounting for differences in maintenance energy requirements of pens with varying average BW, NEg intake was strongly and positively related to ADG (linear and quadratic, P < 0.01; R² = 0.70); however, G:F showed little relationship with NEg intake (P = 0.02; r² = 0.01). Our evaluations with measurements of DMI by cattle in commercial feedlots indicated the shortcomings of current published equations for predicting DMI and suggest the need for development of new equations with improved accuracy and precision. Furthermore, our data indicate that increasing NEg intake increased ADG in a quadratic manner, but did not affect G:F by pens of cattle in feedlots. These findings suggest a diminishing returns effect of energy intake on energy retention.

Genetic variation in domestic and wild elk (Cervus elaphus)

Cronin, M. A., Renecker, L. A., Patton, J. C. — 2008-10-24

Elk (Cervus elaphus) have recently been established as domestic livestock derived from extant wild populations, and may provide insights into changes in genetic variation during domestication. We compared genetic variation at 10 microsatellite DNA loci and the mitochondrial DNA D-loop in 2 herds of domestic elk in Alaska and Canada and wild elk from 8 locations in western North America and Asia. Average individual heterozygosity was 0.55 in domestic elk and 0.47 in wild elk, average allelic richness per locus was 3.7 in domestic elk and 3.5 in wild elk, and 4 mitochondrial DNA haplotypes were observed in domestic elk and 3 in wild elk. Levels of genetic variation were not significantly different among the domestic elk and wild elk we analyzed. Our results are consistent with other studies showing genetic variation can be maintained in domestic and wild populations of elk and other deer with appropriate management.

Effects of forage:concentrate ratio and forage type on apparent digestibility, ruminal fermentation and microbial growth in goats

2008-10-24

The effects of forage type and forage:concentrate ratio (F:C) on apparent nutrient digestibility, ruminal fermentation and microbial growth were investigated in goats. A comparison between liquid (LAB) and solid (SAB) associated bacteria to estimate microbial N flow (MNF) from urinary purine derivative excretion was also examined. Treatments were a 2 x 2 factorial arrangement of forage type (grass hay vs. alfalfa hay) and high vs. low F:C (70:30 and 30:70, respectively). Four ruminally cannulated goats were fed, at maintenance intake, 4 experimental diets according to a 4 x 4 Latin square design. High concentrate diets resulted in greater (P < 0.001) nutrient digestibility except for ADF. However, CP digestibility increased (P < 0.001) only for the high concentrate diets including grass hay. Likewise, N retention, ruminal NH₃-N concentration, and urinary excretion of purine derivatives increased (P < 0.05) with increasing concentrate in animals fed diets based on grass hay (0.23 vs. 0.13 g retained N/g digested N, 30.1 vs. 12.9 mg NH₃-N/100 mL, and 11.5 vs. 8.40 mmol/d, respectively), but not (P > 0.05) when diets included alfalfa hay. Total protozoa numbers and holotricha proportion were higher and lower (P < 0.001), respectively, in high than in low concentrate diets. The F:C affected (P < 0.001) ruminal pH but not total VFA concentration (P = 0.12). Ammonia-N concentration was similar (P = 0.13) over time, whereas pH, VFA concentration, and protozoa numbers differed (P < 0.001) among diets. Estimated MNF was strongly influenced by using either purine bases:N ratio obtained in our experimental conditions or values reported in the literature for small ruminants. There was a F:C effect (P = 0.006) on MNF estimated from LAB but not from SAB. The effect of F:C shifting from 70:30 to 30:70 in goat diets depends on the type of forage used. The MNF measured in goats fed different diets was influenced by the bacterial pellet (LAB or SAB). In addition, the purine bases:N ratio values found were different from those reported in the literature, which underlines the need for these parameters to be analyzed directly in pellets isolated from specific animals and experimental conditions.

Single and joint population analyses of two experimental pig crosses to confirm QTL on SSC6 and LEPR effects on fatness and growth traits

Munoz, G., Ovilo, C., Silio, L., Tomas, A., Noguera, J. L., Rodriguez, M. C. — 2008-10-24

The primary goal of this study was to detect and confirm QTL on pig chromosome 6 (SSC6) for growth and fatness traits in 2 experimental F₂ intercrosses: Iberian x Landrace (IB x LR); and Iberian x Meishan (IB x MS), which were used in this study for the first time in a QTL analysis related to productive traits. For this purpose, single and joint population analyses with single and bivariate trait models of both populations were performed. The presence of the SSC6 QTL for backfat thickness (BFT) previously identified in the IB x LR cross was detected in this population with additional molecular information, but also was confirmed in the IB x MS cross. In addition, a QTL affecting live weight (LW) was detected in both crosses in a similar position to the QTL detected for backfat thickness. This is the first study in which a QTL affecting live weight is detected on SSC6 in the IB x LR cross, as well as in the IB x MS resource population. Furthermore, we analyzed a previously described non-synonymous LEPR SNP located in exon 14 (c.2002C>T) for causality with respect to this QTL within both F₂ populations. Our results supported the previously reported association between LEPR alleles and backfat thickness in the IB x LR cross, and this association was also confirmed within the IB x MS cross. An association not reported before between LEPR alleles and live weight was identified in both populations.

Growing steers grazing high versus low endophyte (Neotyphodium coenophialum)-infected tall fescue have reduced serum enzymes, increased hepatic glucogenic enzymes, and reduced liver and carcass mass

2008-10-24

It is well established that grazing Neotyphodium coenophialum-infected forages results in reduced weight gain and serum prolactin levels of cattle. The objective of this study was to determine the potential effects of toxic endophyte-infected tall fescue consumption on blood metabolites, carcass characteristics, and content of proteins critical for AA metabolism in the liver, kidney, and LM tissue of growing steers. Steers grazed either a low toxic endophyte (LE; 0.023 µg/g ergot alkaloids) tall fescue-mixed grass pasture (n = 9; BW = 266 ± 10.9 kg; 5.7 ha) or a high toxic endophyte (HE; 0.746 µg/g ergot alkaloids) tall fescue pasture (n = 10; BW = 267 ± 14.5 kg; 5.7 ha) from June 14 through at least September 11 (≥ 89 d). No difference was observed for BW (P < 0.10) for the overall 85 d growth period. Also, no differences were observed for ribeye area/100 kg HCW (P > 0.91), backfat (P > 0.95), or backfat/100 kg HCW (P > 0.67). However, ADG (P < 0.01), final live BW (P < 0.05), HCW (P < 0.01), dressing percentage (P < 0.01), ribeye area (P < 0.01), whole liver wet weight (P < 0.01), and whole liver wet weight/100 kg of end live weight (P < 0.01) were greater for LE steers than HE steers. After 85 d of grazing, serum levels of alkaline phosphatase (P < 0.05), alanine aminotransferase (P < 0.01), aspartate aminotransferase (P < 0.03), cholesterol (P < 0.01), lactate dehydrogenase (P < 0.01), and prolactin (P < 0.01) were lower for HE than LE steers. At slaughter, hepatic content of cytosolic phosphoenolpyruvate carboxykinase (P < 0.01) was higher in HE steers than LE steers. Hepatic content of aspartate aminotransferase (P < 0.01) also was higher, whereas renal and LM content were not (P ≥ 0.42). No differences (P ≥ 0.15) were observed for hepatic, renal, and LM content of alanine aminotransferase, glutamate dehydrogenase, glutamine synthetase and three glutamate transport proteins. These data indicate that the HE steers displayed classic endophyte toxicity symptoms for growth and blood parameters, classic symptoms that were concomitant with novelly-identified altered glucogenic capacity of the liver and decreases in carcass characteristics.

Effects of crude glycerin supplementation on performance and meat quality of Holstein bulls fed high-concentrate diets

Mach, N., Bach, A., Devant, M. — 2008-10-24

Forty-eight bulls (335 ± 8.6 kg initial BW) were randomly assigned to 4 glycerin levels (0, 4, 8, and 12% of concentrate DM) with the objective of evaluating the effects of glycerin supplementation on performance, ruminal fermentation, metabolism, and carcass and meat quality in Holstein bulls fed high-concentrate diets. Concentrates were formulated to be isonitrogenous and isocaloric (assuming a glycerin ME content of 3.47 Mcal/kg of DM). Concentrate and straw were fed for ad libitum intake. Bull BW and feed consumption were recorded monthly. Additionally, rumen and blood samples were collected every month. Bulls were slaughtered after 91 d of study (460 ± 11 kg final BW). Hot carcass weight, carcass backfat, and conformation were recorded. The area, Warner-Bratzler shear force, and i.m. fat content of LM were determined. Glycerin level did not affect daily concentrate intake (6.89 ± 0.34 kg/d DM), straw intake (1.38 ± 0.069 kg/d DM), total DMI (8.27 ± 0.32 kg/d DM), ADG (1.36 ± 0.087 kg/d), or G:F (0.17 ± 0.009). Similarly, rumen molar proportions of propionic, acetic, and butyric acids, and rumen liquid osmolality were unaffected by treatment. However, a lesser rumen pH (P < 0.05), and greater rumen total VFA concentration (P = 0.09), serum insulin concentration (P < 0.05), and insulin to glucose ratio (P < 0.05) were observed in bulls fed 8% glycerin in concentrate compared with those receiving 0, 4, or 12%. No changes were observed in carcass and meat quality. The ME content of glycerin (86% glycerol) can be assumed to be 3.47 Mcal/kg of DM in Holstein bulls fed high-concentrate diets. In addition, feeding concentrate containing up to 12.1% of glycerin does not lead to detrimental effects on performance, ruminal fermentation, metabolism, and carcass and meat quality parameters.

Relationships among measures of growth performance and efficiency with carcass traits, visceral organ mass, and pancreatic digestive enzymes in feedlot cattle

2008-10-24

Ninety-three crossbred steer calves (BW ± SD = 385 ± 50 kg) were used (n = 48 steers in yr 1, n = 45 steers in yr 2) to examine the relationship among carcass traits, lean, bone, and fat proportions, visceral tissue weights and pancreatic digestive enzyme activity with DMI, ADG, G:F, and residual feed intake. Calves were progeny from crossbred dams predominately of Angus and Simmental breeding and were sired by Angus, Simmental, crossbred (predominately of Angus and Simmental breeding), Charolais, or Piedmontese bulls. Steers were fed a high moisture corn-based diet for an average of 112 d. Partial correlation analysis accounting for yr, pen within yr, wk of slaughter within yr and sire breed was conducted. Gain:feed was negatively correlated (P ≤ 0.04) with backfat thickness (r = -0.38), marbling score (r = - 0.32), and trim and kidney fat weight proportion (g/kg BW; r = -0.42). Residual feed intake (P = 0.008; g/kg BW; r = 0.34) and backfat-corrected RFI (P = 0.005; r = 0.29) was positively correlated with trim and kidney fat weight proportion. Gain:feed was negatively correlated (P < 0.001) with total fat weight proportion (g/kg rib; r = -0.45) and positively correlated (P ≤ 0.03) with lean weight proportion (g/kg rib; r = 0.30) and bone weight proportion (g/kg rib; r = 0.28). Gain:feed was negatively correlated (P ≤ 0.01) with subcutaneous fat weight proportion (g/kg rib; r = -0.32) and intermuscular fat weight proportion (g/kg rib; r = 0.37). Gain:feed was negatively correlated (P < 0.001) with total visceral weight proportion (g/kg BW; r = -0.44) and visceral fat weight proportion (g/kg BW; r = -0.41) but was positively correlated (P = 0.02) with spleen weight proportion (g/kg BW; r = 0.30). There were no significant correlations (P > 0.10) between performance measures and the pancreatic proportional content of -amylase and trypsin activity (units/kg BW). These data indicate that carcass fatness traits and changes in the proportional weight of total viscera may be negatively associated with G:F and that visceral fat weight proportion and trim and kidney fat weight proportion may be important factors influencing this relationship.

ASAS Centennial Paper: Contributions in the Journal of Animal Science to the development of protocols for breeding management of cattle through synchronization of estrus and ovulation

Lauderdale, J. W. — 2008-10-24

ASAS Members, publishing in Journal of Animal Science (JAS), completed research that resulted in understanding the estrous cycle of cattle, which led to the ability to inseminate cattle on a given day with pregnancy rates similar to those achieved by 21 d breeding by a fertile and sound bull. Research published in JAS led to understanding estrus, ovulation, the estrous cycle, and postpartum interval for cattle (1930s through 1960s) and hormonal factors affecting corpus luteum lifespan of cattle (1950s through 1980s). Research during the 1940s to 1960s, using gonadotropins and progesterone to manage the estrous cycle of cattle, established the concepts for estrus synchronization and stimulated commercial research directed at developing cost-effective progestogen estrus synchronization products, leading to commercially available products from 1967 through today (Repromix, MGA, Syncro-Mate-B, CIDR). Prostaglandin F₂ (PGF₂) products were approved for estrus synchronization (1970s, 1980s) and GnRH products were approved for use in cattle to treat ovarian follicular cysts (1970s, 1980s). Research published in JAS was essential for understanding the biology of and potential value of both PGF₂ and GnRH and contributed both to new knowledge and scientific bases for future Food and Drug Administration Center for Veterinary Medicine approval of those products. Research during the1980s through 2000s led to understanding ovarian follicular waves and described the timing of follicular recruitment, selection, dominance and atresia; this research was essential for the ability to effectively manage follicles to achieve success with timed AI (TAI). The knowledge gained through research published in JAS resulted in development of the numerous estrus synchronization and breeding management protocols that are cost-effective and meet the breeding management "needs" of most beef and dairy enterprises.

ASAS Centennial Paper: Future needs in animal breeding and genetics

Green, R. D. — 2008-10-24

The past century has seen animal breeding and genetics evolve and expand from definition and validation of basic population genetics theory to development of selection index theory to today's relatively sophisticated genetic prediction systems enabling industry genetic improvement. The end of the first century of the American Society of Animal Science also coincides with the rapid movement of the field into the era of genome-enabled genetic improvement and precision management systems. Led by recent research infrastructure investments by the U.S. and international partners to develop chicken, bovine, swine, ovine, and equine "genome toolboxes", the animal breeding community is poised to play a crucial role in the century to come. These genome toolboxes provide the needed platforms for developing whole genome selection programs based on linkage disequilibrium for a wide spectrum of traits; allow the opportunity to re-define genetic prediction based on allele sharing as opposed to traditional pedigree relationships; and provide for the first time simultaneous information upon which to practice genetic selection and plan precision management of specific genotypes, all early in the life of the animal. An area of major focus will be mining of the genomes through systems biology approaches to better understand gene and metabolic networks --what has previously been lumped into poorly understood genotype by environment and genotype by genotype interactions. Perhaps the greatest obstacle to the successful merger of genomic and quantitative approaches will be the lack of necessary animal resource populations to appropriately define and measure phenotypes, i.e., the so-called "phenomic gap", for difficult to measure traits such as resistance to disease and stress, adaptability, longevity, and efficiency of nutrient utilization. Additionally, due to de-emphasis of quantitative genetics and animal breeding programs in academia over the past quarter century, a dearth of qualified young scientists to effectively mine the genomes must immediately be addressed. Whilst the motivating factors may have changed, the need for high quality animal breeding and genetics research and education has never been higher.

BOARD-INVITED REVIEW: Using behavior to predict and identify ill health in animals

Weary, D. M., Huzzey, J. M., von Keyserlingk, M. A.G. — 2008-10-24

We review recent research in one of the oldest and most important applications of ethology; evaluating animal health. Traditionally, such evaluations have been based on subjective assessments of debilitative signs; animals are judged ill when they appear ‘depressed’ or ‘off feed’. Such assessments are prone to error, but can be dramatically improved with training using well-defined clinical criteria. The availability of new technology to automatically record behaviors allows for increased use of objective measures; automated measures of feeding behavior and intake are increasingly available in commercial agriculture and recent work has shown these to be valuable indicators of illness. Research has also identified behaviors indicative of risk of disease or injury. For example, the time spent standing on wet, concrete surfaces can be used to predict susceptibility to hoof injuries in dairy cattle, and time spent nuzzling the sow’s udder can predict the risk of crushing in piglets. One conceptual advance has been to view decreased exploration, feeding, social, sexual and other behaviors, as a coordinated response that helps afflicted individuals recover from illness. We argue that the ‘sickness behaviors’ most likely to decline are those that provide longer-term fitness benefits (such as play), as animals divert resources to those functions of critical short-term value such as maintaining body temperature. We urge future research assessing the strength of motivation to express sickness behaviors, allowing for quantitative estimates of how sick an animal feels. Finally, we call for new theoretical and empirical work on behaviors that may act to signal health status, including behaviors that have evolved as honest (i.e. reliable) signals of condition for offspring-parent, inter- and intra-sexual and predator-prey communication.

Heritability of juniper consumption in goats

2008-10-24

Data from goats (N=505), collected over a 4 yr period, were used to estimate the heritability of juniper consumption. Juniper consumption was determined by near infra-red spectroscopy on fecal samples (N=1,080) collected from female Boer-cross goats grazing pastures with a variety of plants, including juniper. The animals with records were progeny of 72 sires. Individual goats had from 1 to 4 observations over a 4 yr period. Predicted juniper consumption for individual observations ranged from -5 to +62% of the diet. Data were analyzed with a mixed model that included management group as a fixed effect, body weight as a covariate, and permanent environment, animal, and residual as random effects. Management group was a significant source of variation. Least squares means of juniper consumption, as a percentage of the total intake, for management groups varied from 19 to 47%. Heritability of juniper consumption was 13%. Repeatability of juniper consumption was 31%. These results suggest that progress to selection for goats that will consume greater amounts of juniper is obtainable, but is expected to be slow.

The addition of ground wheat straw as a fiber source in the gestation diet of sows and the effect on sow and litter performance for three successive parities

2008-10-24

A regional experiment was conducted at 8 experiment stations with a total of 320 sows initially to evaluate the efficacy of adding 13.35% ground wheat straw to a corn-soybean meal gestation diet for 3 successive gestation-lactation (reproductive) cycles compared with sows fed the control diet without straw. There were a total of 708 litters farrowed over 3 reproductive cycles. The basal gestation diet intake averaged 1.95 kg daily for both treatments, plus 0.30 kg of straw daily for sows fed the diet containing ground wheat straw (total intake of 2.25 kg/d). During lactation, all sows on both gestation treatments were fed ad libitum the standard lactation diet used at each station. Response criteria were sow farrowing and rebreeding percentages, culling factors and culling rate, weaning to estrus interval, sow BW and backfat measurements at several time points, and litter size and total litter weight at birth and weaning. Averaged over 3 reproductive cycles, sows fed the diet containing wheat straw farrowed and weaned 0.51 more pigs/ litter (P ≤ 0.04), and had total litter birth and weaning weights that were 0.87 and 3.59 kg heavier (P = 0.01), respectively, than sows fed the control gestation diet. Sows fed the gestation diet containing wheat straw consumed more (P = 0.01) lactation diet/d than control sows. There were no gestation diet treatment differences for any sow fate criteria (farrowing and rebreeding percentages, and culling rate), sow BW and backfat measurements, or weaning to estrus interval. Lactation diet intake and all sow BW and backfat measurements increased with increasing parity. In conclusion, when the daily intake of the basal gestation diet was equalized for both treatments, the addition of 13.35% ground wheat straw to the gestation diet improved sow and litter performance with increases in litter size and total litter weight at birth and weaning compared with control sows and litters.

Performance and digestibility characteristics of finishing diets containing distillers grains, composites of corn processing coproducts, or supplemental corn oil

2008-10-24

Three experiments evaluated the lipids in distillers grains plus solubles compared with corn or other sources of lipid in finishing diets. Experiment 1 utilized 60 individually fed yearling heifers (349 ± 34 kg) fed treatments consisting of 0, 20, or 40% (DM basis) wet distillers grains plus solubles (WDGS), or 0, 2.5, or 5.0% (DM basis) corn oil in a finishing diet based on high-moisture corn (HMC) and dry-rolled corn (DRC). Cattle fed 20 and 40% WDGS had greater (P < 0.10) G:F than cattle fed 0% WDGS. Cattle fed the 5.0% corn oil had lower overall performance than cattle fed the other diets. Results from Exp. 1 indicated that adding fat from WDGS improves performance, whereas supplementing 5.0% corn oil depressed G:F, suggesting that the fat within WDGS is different than corn oil. Experiment 2 used 234 yearling steers (352 ± 16 kg) fed 1 of 5 treatments consisting of 20 or 40% (DM basis) dry distillers grains plus solubles (DDGS), 1.3% or 2.6% (DM basis) tallow, or HMC. All diets contained 20% (DM basis) wet corn gluten feed (WCGF) as a method of controlling acidosis. No differences between treatments for any performance parameters were observed in Exp. 2. The DDGS may be similar to tallow and HMC in finishing diets containing 20% WCGF. Experiment 3 used 5 Holstein steers equipped with ruminal and duodenal cannulas in a 5x5 Latin square design. Treatments were a 40% WDGS diet, 2 composites, one consisting of corn bran and corn gluten meal (COMP), and one consisting of corn bran, corn gluten meal, and corn oil (COMP + OIL), and 2 DRC-based diets supplemented with corn oil (CON + OIL) or not (CON). Cattle fed the WDGS diet had numerically lower rumen pH compared with cattle fed other treatments. Cattle fed WDGS had greater (P < 0.10) molar proportions of propionate, lower (P < 0.10) acetate:propionate ratios, greater (P < 0.10) total tract fat digestion, and a greater (P < 0.10) proportion of unsaturated fatty acids reaching the duodenum than cattle fed other treatments. Therefore, the higher energy value of WDGS compared with corn may be due to more propionate production, higher fat digestibility, and more unsaturated fatty acids reaching the duodenum.

Feed preference in pigs: Relationship with feed particle size and texture

Sola-Oriol, D., Roura, E., Torrallardona, D. — 2008-10-24

In previous studies, we have observed important differences in feed preference in pigs because of changes in only 1 dietary ingredient. The present experiment was conducted to study the relationship between the previously reported feed preference values of feeds and their particle size and texture characteristics. The effect of individual feed ingredients, added to a common basal diet, was studied. In addition to the basal diet containing rice, a soybean meal product containing 56% CP, sunflower oil, and wheat bran, a total of 126 diets were studied. Of these, 63 were prepared by replacing rice in the basal diet with another cereal, 29 by replacing the soybean product with different protein sources, 19 by replacing sunflower oil with different lipid sources, and 6 by replacing wheat bran with different fiber sources. Cereals were studied at inclusion rates of 150, 300, and 600 g·kg^-1, protein sources were studied at 50, 100, and 200 g·kg^-1, lipids were studied at 15, 30, and 100 g·kg^-1, and fiber sources were studied at 65 and 130 g·kg^-1. The particle size profile of all the diets was determined with a 9-screen sieve shaker. The geometric mean particle size (d_gw), particle size uniformity (s_gw), number of particles per gram, and surface area (cm²·g^-1), and % of fine (passing through a 250-µm sieve), and coarse particles (remaining in a 2,000-µm sieve) were calculated. The texture properties (hardness, fragility, chewing work, and adhesiveness) of the feeds were also determined with a texture analyzer. The Pearson’s correlation coefficients of these variables with feed preference were: d_gw (r = 0.07; P = 0.45), s_gw (r = 0.16; P = 0.07), number of particles per gram (r = -0.05; P = 0.61), surface area (r = -0.07; P = 0.46), % of coarse particles (r = 0.04; P = 0.65), % of fine particles (r = -0.12; P = 0.19), hardness (r = -0.21; P = 0.02), fragility (r = -0.20; P = 0.03), chewing work (r = -0.33; P < 0.001), and adhesiveness (r = 0.02; P = 0.78). It is concluded that the texture properties of the feed may explain in part the feed preferences observed in pigs; whereas, particle size characteristics have less impact.