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ANIMAL NUTRITION |
* Department of Animal & Range Sciences, North Dakota State University, Fargo 58105; and
Carrington Research Extension Center, North Dakota State University, Carrington 58421
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Abstract |
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 Top Abstract INTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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0.03) acetate molar proportion than control. Ruminal pH (P = 0.18) and NH3 (P = 0.14) were not different among treatments. In Exp. 2, calves fed chickpea, field pea, and lentil had greater overall DMI (7.59 vs. 6.98 kg/d; P 0.07) and final BW (332 vs. 323 kg; P 0.04), whereas chickpea and lentil had greater ADG (1.90 vs. 1.71 kg/d; P 0.04) than control. Gain efficiency (P = 0.18) did not differ among treatments. Steers fed pulse grains had similar CP and OM digestibilities compared with a combination of corn and canola meal in receiving diets. Pulse grains are a viable alternative for replacement of protein supplements in receiving diets for beef cattle.
Key Words: chickpea • digestion • field pea • lentil • receiving • steer
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INTRODUCTION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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). Field peas (Pisum sativum), lentils (Lens esculenta), and chickpeas (Cicer arietinum L.) are cool-season legumes well adapted to the soil and climate of the Northern Plains (Miller et al., 2002). Pulse crops are nutrient-dense feed grains (Bhatty et al., 1976; Chaven et al., 1986; Reed et al., 2004) containing moderate levels of CP and are highly digestible. The premium market for pulse grains is human food, where prices are often greatest (Janzen et al., 2004). Pulse grains that do not meet quality standards for human consumption are marketed at screenings prices as livestock feed (Stanford et al., 1999). Peas have been incorporated into diets for sheep, dairy, and beef with positive results (Corbett et al., 1995; Loe et al., 2000; Reed et al., 2004). Data from previous beef research trials indicates that peas are very palatable (Corbett, 1997) and improve G:F in growing (Chen et al., 2003) and finishing diets (Birkelo et al., 2000; Flatt and Stanton, 2000).
There is a limited but growing body of nutritional information on feeding field pea to ruminants (Loe et al., 2000; Reed et al., 2004; Gelvin et al., 2004). However, research related to the use of chickpea and lentil in ruminant diets is limited. We hypothesized that replacing corn and canola meal with pulse grains in receiving diets of beef cattle would have little effect on digestive responses.
Our objective was to evaluate the effects of replacing corn and canola meal with pulse grains on the receiving performance on newly weaned steers, and on intake, digestion, microbial efficiency, and ruminal fermentation in steers fed receiving diets.
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MATERIALS AND METHODS |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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Animal Diets and Treatments. All animal care, handling techniques, and surgical procedures were approved by the North Dakota State Institutional University Animal Care and Use Committee before the initiation of the research. Eight Holstein (615 ± 97 kg of initial BW) and 8 Angus-crossbred steers (403 ± 73 kg of initial BW) were used in a randomized complete block design to evaluate the effects of replacing a portion of corn and canola meal in growing diets with pulse grains (field pea, chickpea, and lentil). Steers were housed in an enclosed barn in individual stanchions (1.2 x 2.2 m) on rubber mats that allowed for separation of urine and feces. Steers were fed diets in the form of a totally mixed ration at 0700 and 1900 daily and were allowed free access to water. Diets were offered to ensure ad libitum intakes and 10% feed refusal daily.
Diets consisted of 50% grass hay (8.9% CP, 74.4% NDF, 44.8% ADF, and 9.3% ash) chopped in a tub-grinder (Haybuster, model H-11000 tilt, DuruTech Industries, Jamestown, ND) to pass through a 3.81-cm screen; 41% dry rolled corn, canola meal, or pulse grain; 5% sugar beet concentrated separator by-product; and 4% supplement (DM basis; Table 1). Treatments consisted of 1) corn and canola meal (control), 2) corn and chickpea, 3) corn and field pea, and 4) corn and lentil (Table 1), with the pulse grain replacing corn and canola meal in the concentrate mixture. Diets were formulated to contain a minimum of 12% CP (DM basis) and minimum calcium to phosphorus ratio of 2:1. Pulse grains were processed (dry rolled) by roller mill (model K, Roskamp Mfg. Inc., Cedar Falls, IA). Particle size (ANSI/ASAE, 2003) for feed grains used in this study was determined by a modified screen set in which screen numbers 200 and 270 were removed and screen sizes 3 and 4 were added at the top of the screen set to accommodate the larger particle size of field pea and chickpea grains. A standard screen set was used for the lentil and corn grains. Particle size for feed grains in this study were 3,282 µm for chickpea, 3,438 µm for field pea, 2,105 µm for lentil, and 2,468 µm for corn.
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On d 18, ruminal fluid samples were collected at –2, 0, 2, 4, 6, 8, 10, and 12 h after feeding. After the collection at –2 h, the rumen was dosed with 200 mL of a CoEDTA solution (20 g of Co/L) to determine the ruminal liquid dilution rate (Uden et al., 1980). Ruminal fluid samples of 200 mL were drawn using a suction strainer, and pH was recorded using a pH meter and combination electrode (model 2000, Beckman Instruments Inc., Fullerton, CA). A 3-mL sample of ruminal fluid was retained, and 1 mL of 25% (wt/vol) HPO3 was added to the sample in a 12- x 75-mm culture tube. Samples were stored at –20°C until analysis for NH3 and VFA.
On d 21, ruminal evacuations were performed to determine DM fill. Ruminal contents were removed, weighed, and mixed, with a subsample retained for DM analysis. A 4-kg sample was taken, and 2 L of 3.7% (wt/vol) formaldehyde in 0.9% NaCl was added (Zinn and Owens, 1986) for isolation of bacterial cells and analysis for DM, ash, N, and purines. Samples were stored at –20°C until analysis.
Laboratory Analysis. Diet, orts, ruminal content, and fecal samples were dried in a forced-air oven at 50°C (model SB-350, Grieve Corp.) for 48 h. Dried samples were ground with a Wiley mill (2-mm screen; model 3, Arthur H. Thomas, Philadelphia, PA). Duodenal samples were lyophilized (Virtis Genesis 25LL, Virtis Co. Inc., Gardiner, NY) and ground in a blender (Osterizer Galaxie Pulse Matic I6, Sunbeam, Purvis, MS).
Dietary, orts, fecal, and duodenal samples were analyzed for DM, ash, N (methods 4.1.06, 4.1.10, 4.2.10, respectively; AOAC, 1997), and ADF and NDF (Ankom Technology, Fairport, NY). Ruminal content samples were analyzed for DM (method 4.1.06; AOAC, 1997). Dietary ingredient samples (corn, canola meal, field peas, lentils, and chickpeas) were also analyzed for starch (Herrera-Saldana and Huber, 1989). Duodenal samples were analyzed for Cr by using the spectrophotometric method of Fenton and Fenton (1979). Chromium concentrations were used to calculate digesta flow. Digestibility was calculated by subtracting flow rate from intake and dividing by intake.
Ruminal fluid samples were centrifuged at 20,000 x g for 20 min. Liquid was filtered through a 0.45-µm filter and the supernatant was analyzed for ammonia (Broderick and Kang, 1980). Ruminal VFA concentrations were determined by GLC (Hewlett Packard 5890A Series II GC, Wilmington, DE) and separated on a capillary column (Nukol, Supelco, Bellefonte, PA) using 2-ethyl butyric acid as the internal standard (Goetsch and Galyean, 1983).
Bacterial cells were isolated from formaldehyde-treated ruminal contents. Ruminal contents were blended (Model 37b119, Waring, New Hartford, CT), and the mixture was strained through 2 layers of cheesecloth. Feed particles and protozoa in the ruminal samples were removed by centrifugation at 500 x g for 20 min. The supernatant was then centrifuged at 30,000 x g for 20 min to pellet the bacteria. Isolated bacteria were frozen, lyophilized, and analyzed for DM, ash, N (methods 4.1.06, 4.1.10, 4.2.10, respectively; AOAC, 1997), and purines (Zinn and Owens, 1986).
Calculations.
Microbial OM and N leaving the abomasum were calculated using purines as microbial markers (Zinn and Owens, 1986). Organic matter fermented in the rumen was OM intake minus the difference between the amount of total OM reaching the duodenum and microbial OM reaching the duodenum. Feed N escape to the small intestine was calculated by subtracting microbial N from total N and thus includes any endogenous and ammonia N contributions. Liquid dilution rate was calculated by the regression of the natural logarithm of the Co concentration on sampling time.
Statistical Analysis.
Data were analyzed as a randomized block design using the MIXED procedure (SAS Inst. Inc., Cary, NC). Animals were blocked by breed, resulting in 2 Holstein and 2 Angus steers per treatment. No block effects were detected, and block was dropped from the model statement. As a result, the final statistical model included only the fixed effect of treatment (supplement source), with no random effects. Ruminal data over time were analyzed using the MIXED procedure of SAS. The statistical model included fixed effects for treatment, time, and treatment x time, with the repeated subject being animal nested within treatment. After evaluation of 3 covariance structures for the repeated measures data (Wang and Goonewardene, 2004), it was determined that compound symmetry provided the best fit to the data. Pre-planned orthogonal contrasts were conducted between control vs. chickpea, control vs. field pea, and control vs. lentil.
Experiment 2
Animal Diets and Treatments.
All animal care and handling techniques followed guidelines recommended in the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching (FASS, 1999).
One hundred seventy-six mixed-breed steers from 40 ranches in North Dakota and Montana (initial BW of 254 ± 19 kg) were allotted by BW and source to 1 of 4 receiving diets (Table 2) containing chickpea, field pea, lentil, or corn and canola meal as an energy and protein source. One-day BW were collected 3 times (initial, d 18, and final) during the study, but only initial and final BW were reported. Steers were not held off feed or water before weighing. Diets were formulated to contain a minimum of 16% CP and 1.12 Mcal of NEg/kg (DM basis). Cattle were fed at the Carrington Research Extension Center in 16 pens (11 steers per pen; 4 pens per treatment). Feed was delivered as a totally mixed ration once daily to appetite. Cattle were fed in open dry-lot pens equipped with automatic waterers and fence line bunks, which allowed for 0.61 m of bunk space per steer. Experimental diets were fed for 39 d.
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Statistical Analysis.
Data were analyzed using the MIXED procedure of SAS. The model for the completely randomized design included only the fixed effect of treatment (concentrate source), with no random effects. Preplanned orthogonal contrasts, which are discussed only when a significant (P 0.10) treatment F-test was detected, were conducted between canola meal and each of the pulse grains.
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RESULTS AND DISCUSSION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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Dietary nutrient profile of the individual ingredients is available in Table 3. The laboratory starch content for corn and field peas used in our study was lower than expected. Crude protein, NDF, and ADF content of individual dietary ingredients were within expected ranges.
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). Reed et al. (2004) replaced corn with field peas in diets that consisted of 50% corn, 23% corn silage, 23% alfalfa hay, and 4% supplement, and reported that DMI was not affected by increasing inclusion of field peas in receiving diets for cattle. Similarly, Soto-Navarro et al. (2004) reported similar DMI when field peas replaced wheat middlings, soybean hulls, and barley malt sprouts in the concentrate mixture of a 45% forage:55% concentrate totally mixed ration fed to steers. In contrast, Stanford et al. (1999) reported linear decreases in DMI of lambs fed 75% concentrate diets in which lentil screenings replaced barley and canola meal at 12.5, 25, and 33% of diet DM.
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), no differences in ruminal DM fill were observed (P = 0.64; Table 4). Similarly, Soto-Navarro et al. (2004) reported no difference in ruminal DM fill.
No differences were observed among treatments for OM intake (P = 0.63), OM flow to the small intestine (P = 0.38), and microbial OM flow (P = 0.53; Table 5). Similarly, no effects were observed for postruminal OM digestion (P = 0.15). Total tract digestibility of OM averaged 64.2% for pulse grains and 64.7% for the control and was not different among treatments (P = 0.40). Apparent ruminal OM digestibility was greater (P = 0.05; Table 5) for the lentil treatment compared with control. We are uncertain as to why lentils were the only pulse grain that had OM digestibility greater than the control. Lentils were the only pulse grain to have a smaller particle size than corn (2,105 vs. 2,468 µm), which may partly explain the response. A key process in bacterial fermentation of feed particles is attachment of rumen microflora to the feed; approximately 75% of starch fermentation is associated with bacterial attachment to feed particles (Huntington, 1997). The potential differences in rate and extent of ruminal degradation of the starch due to the greater surface area of the lentils as well as differences in the characteristics of the starch component between lentils and corn may have been factors. Pulse grains contain more CP with a greater proportion of rumen-degradable protein (RDP) and are lower in starch than corn, which may have contributed to some of the observed differences in ruminal OM digestion.
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). Crude protein intake, CP flow to the small intestine, and microbial CP flow (P = 0.78, 0.38, and 0.46; respectively) were not different among treatments. Total-tract CP digestion (P = 0.45) was also not affected by treatment. Rumen-degradable protein of field peas is 78% (NRC 1988), whereas RDP values for corn and canola meal are 45 and 72%, respectively (NRC, 1996). From the aforementioned NRC values, we calculated RDP from the corn and field pea treatment to be 68.4%, and the control treatment at 59.8% RDP. Based on these calculations we expected the field pea treatment to have greater ruminal CP digestion and lower CP flow to the duodenum relative to control, but this did not occur. Reasons for this response are unclear, but they may be related to reduced microbial degradation of the forage CP on the field pea treatment, which in turn, may have contributed to the greater intestinal CP levels we observed on the field pea treatment. Steers on the field pea treatment had lower total VFA concentration (P = 0.005) than the control treatment. Soto-Navarro et al. (2004) reported decreased in situ forage CP degradation while feeding increasing levels of field peas to steers. Reed et al. (2004) reported a linear increase in CP intake and total N flow to the duodenum when feeding increasing levels of field peas in receiving diets for cattle. Microbial efficiency (g of microbial N/kg of truly OM fermented) was not different (P = 0.18; 17.0 ± 1.2) among treatments and was within expected ranges (Caton et al., 1994).
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). Intake of NDF (P = 0.18) and ADF (P = 0.11) were similar for pulse grains vs. control. Total-tract NDF and ADF digestion were not affected by the inclusion of chickpea (P = 0.68 and 0.55, respectively, for NDF and ADF) or lentil (P = 0.83 and 0.98, respectively, for NDF and ADF).
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; Leupp et al., 2006). Leupp et al. (2006) reported lower values for total-tract NDF digestion than for ruminal NDF digestion when supplementing whole and ground canola to steers offered grass hay ad libitum. Perez-Maldonado and Norton (1996) reported increases in ADF flow along the digestive tract in sheep and goats fed a basal diet of pangola grass supplemented with tropical legumes containing tannins. In their research, diets containing Desmodium intortum had total dietary tannin levels of 9.5 g/kg of DM, whereas diets containing Calliandra calothyrsus contained total dietary tannin levels of 22.5 g/kg of DM. They attributed the negative postruminal ADF digestibilities to condensed tannins present in the tropical forages that were fed.
We did not measure tannin content in the legume grains fed in this study. However, legume grains such as field peas, lentils, and chickpeas contain tannins. This may partially explain the responses. Nikolopoulou et al. (2007) measured tannin content of several field pea varieties over 2 growing seasons. Total tannin content ranged from 0.45 to 0.92% of DM. Wang et al. (1998) measured condensed tannin content in several varieties of field pea grown in Manitoba and reported values that ranged from 0.89 to 5.18 g/kg of DM. Wang and Daun (2006) reported that the tannin content of several lentil varieties ranged from 0.40 to 1.01% with a mean of 0.64%. Rincón et al. (1998) measured tannin content of Desi- and Kabuli-type chickpeas and the averages were 0.671 and 0.489 catechin units/100 g of DM, respectively.
However, dietary tannin content does not explain the small, negative intestinal digestibilities for NDF and ADF in the control diet. Titgemeyer (1997) discussed various error sources in digestibility research. It is also possible that our small, negative intestinal digestibilities were due to errors related to the flow marker used.
Ruminal pH (P = 0.18; Table 8) was not different among treatments, averaging 6.42 for the control vs. 6.35 for the average of the pulse grains. In other research, Soto-Navarro et al. (2004) reported minimal changes in pH when feeding increasing levels of field peas in medium-concentrate diets. In some situations in which cereal grains are used as supplements for forage-based diets, ruminal pH can be decreased (Sanson et al., 1990); however, the results are not universal, particularly when grain inclusion is at low to moderate levels, as was the case in the current study. In addition, supplementation of RDP has resulted in lower ruminal pH (Bodine et al., 2000; Köster et al., 1996) presumably through increased ruminal fermentation when RDP is supplemented to diets based on low-quality forage.
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reported a cubic increase in total VFA with increasing field pea level in growing diets for beef cattle. In contrast, Soto-Navarro et al. (2004) observed no differences in ruminal fermentation variables when feeding increasing levels of field pea to cattle. Ruminal pH was similar among treatments and therefore a change in total VFA concentration was unexpected.
Ruminal acetate concentrations for chickpea (P = 0.02; 58.8 vs. 63.6 mM), field pea (P = 0.03; 60.5 vs. 63.6 mM), and lentil (P = 0.01; 60.1 vs. 63.6 mM) were lower than for control (Table 8). There was a sampling time x treatment interaction for ruminal NH3 concentration (P = 0.04). At the 2-h sampling time, the control diet was lower in ruminal NH3 than the chickpea diet (P = 0.001). Ruminal NH3 for control was lower for chickpeas (P = 0.08) at the 4-h sampling time. The control was lower in ruminal ammonia at the 6-h sampling time than chickpeas (P = 0.08) and lentils (P = 0.002). Ruminal ammonia concentration for all treatments was adequate and above the level suggested by Satter and Slyter (1974) to support optimal ruminal digestion.
Experiment 2
When data were analyzed for the entire 39-d trial, cattle fed pulse grains had greater DMI (P 0.07; 7.59 vs. 6.98 kg/d) than those fed the control treatment (Table 9). In addition, ADG for cattle fed chickpea (P = 0.03) and lentil (P = 0.04) were greater than for control. Gain efficiency was not different (P = 0.18) among treatments. The diets were formulated to have similar dietary energy concentrations, and the differences in DMI may be an indication that pulse grains were more palatable than corn and canola meal when fed to newly weaned cattle.
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These data suggest that pulse grains are a suitable substitute for corn and canola meal in receiving diets for beef cattle. We observed minimal effects on digestive and fermentation characteristics with the inclusion of pulse grains in diets for receiving cattle. Our feedlot trial suggested that early advantages in DMI could be attained by replacing corn and canola meal with pulse grains in receiving diets for freshly weaned cattle. Cattle feeders may benefit from the inclusion of pulse grains through improved DMI, which in turn may alleviate nutrient deficiencies that can occur in receiving calves.
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Footnotes |
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1 Corresponding author: gregory.lardy{at}ndsu.edu
Received for publication September 22, 2006. Accepted for publication June 20, 2007.
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LITERATURE CITED |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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