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ANIMAL NUTRITION |
* Department of Animal Sciences, Louisiana State University Agricultural Center, Baton Rouge 70803;
and
Research and Nutritional Services, Zinpro Corporation, Eden Prairie, MN 55344
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Abstract |
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 Top Abstract INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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Key Words: intestinal villi • lactation • nursery • pig • tissue
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INTRODUCTION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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; Baker and Ammerman, 1995). A deficiency in Zn can result in abnormalities in fetal or skeletal growth, general body growth retardation, or dermatitis (Baker and Ammerman, 1995; Shelton et al., 2005).
Diets for pigs are generally supplemented with Zn to ensure dietary adequacy, and the supplemental Zn source usually has been inorganic Zn from ZnSO4 or ZnO, with ZnSO4 having a greater bioavailability (NRC, 1998). However, organic forms of Zn, such as ZnMet or ZnLys, also have been evaluated because of the perceived greater bioavailability relative to the inorganic sources of Zn. A greater bioavailability would result in better use by the pig and less excretion by the animal. Although better use of the organic sources of Zn has been demonstrated in poultry (Wedekind et al., 1992) and nursery pigs (Ward et al., 1996), many researchers have reported no differences between organic and inorganic sources of Zn (Hill et al., 1986; Hahn and Baker, 1993; Wedekind et al., 1994; van Heugten et al., 2003).
Despite numerous reports on the effects of Zn in nursery and growing-finishing pigs, information on the effects of Zn source on sow and subsequent pig performance is lacking. In poultry, the immunity of progeny was enhanced when broiler breeder hens were fed supplemental Zn (Kidd et al., 1992, 1993). Similarly, Caine et al. (2001) reported that a Zn AA complex (ZnAA) fed from d 80 of gestation to farrowing had a positive effect on intestinal development and immune function in pigs 24 h after being weaned at 14 d of age, but these researchers did not report data on pigs during the nursery period. Furthermore, Hostetler and Kincaid (2004) suggested that Zn is acquired by the porcine fetus during early development for support of cell proliferation and tissue differentiation of developing organs. Thus, our objective was to compare the effects of ZnSO4 with ZnAA on the sow and her progeny when fed to the sow during gestation and lactation and then fed to the nursery pigs.
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MATERIALS AND METHODS |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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Three dietary treatments were fed to sows and their pigs during the gestation, lactation, and nursery phases. The treatments were 1) a corn-soybean meal diet with 100 ppm Zn from ZnSO4 in the trace mineral premix (control); 2) control + 100 ppm additional Zn from ZnSO4; and 3) control + 100 ppm additional Zn from ZnAA (Availa Zn, Zinpro Corporation, Eden Prairie, MN). Dietary additions were made on an as-fed basis.
The composition of the gestation, lactation, and nursery control diets is shown in Table 1, and all diets were fed in mash form. The gestation diet was formulated to meet or exceed the NRC (1998) requirements of gestating sows with an anticipated weight change of 30 kg with 12 pigs per litter. The lactation diet was formulated to meet or exceed the NRC (1998) requirements of lactating sows with an anticipated weight change of –10 kg and pig ADG of 0.20 kg. The gestation and lactation control diets were formulated to provide 105% of the apparent digestible AA requirements suggested by the NRC (1998), and all other nutrients met or exceeded the nutrient requirements suggested by the NRC (1998).
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Gestation and Lactation
Thirty-one primaparous and multiparous Yorkshire and crossbred (Yorkshire x Landrace or Yorkshire x Duroc) sows from the Louisiana State University Agricultural Center Swine Unit were allotted to treatment on d 15 of gestation on the basis of parity, body condition, weight, and date of d 110 of gestation. During the gestation phase, each treatment was replicated 2 times, and the sows were group-penned in 2.4 x 3.7 m pens by replicate (5 or 6 sows per replicate) within treatment according to their body condition and weight. During gestation, sows were fed once per day, and the amount of feed per sow was based on body condition. The ADFI during gestation was approximately 2.7 kg. All sows were individually weighed and checked for pregnancy on approximately d 80 of gestation. At that time, 6 sows were removed from the project because they were not pregnant (1 sow from control, 3 sows from ZnSO4, and 2 sows from ZnAA).
The sows were individually weighed and moved into the farrowing facility on d 110 of gestation. The farrowing facility was an environmentally controlled building with 28 individual stalls and an under-floor flush system. Each farrowing stall was 1.5 x 2.1 m with a cast-iron floor for the sow and a hard plastic floor for the pigs. Each stall had a stainless-steel feeder with 2 nipple waterers (1 for the sow and 1 for the pigs). The sows were maintained on the gestation diets from d 110 of gestation until farrowing. After farrowing, the sows were not offered feed for the first day, but beginning on d 1 postfarrowing, they were offered the lactation treatment diets 3 times a day until weaning to approximate ad libitum intake.
Within 24 h of farrowing, the litters were weighed, ear-notched, and given a 1-mL shot of iron dextran (Ferrodex 100, Agri Laboratories Ltd., St. Louis, MO). The umbilical cord of each pig was sprayed with iodine, and needle teeth were clipped if necessary. Within 36 h of farrowing, attempts were made via cross-fostering within treatment to adjust each litter to approximately 10 pigs per sow, and all sows weaned at least 8 pigs. The pigs were weaned at an average age of 17 d, and all pigs were weaned on the same day regardless of the farrowing date. The sows and feed containers were weighed at weaning for calculation of ADG and ADFI during lactation.
Nursery
Two hundred and two pigs (63, 55, and 84 pigs for control, ZnSO4, and ZnAA treatments, respectively) were allotted and distributed to pens, within the same treatment as their dams, on the basis of BW at weaning. Each pen had 7 pigs, except for 1 pen in the ZnSO4 treatment, which had 6 pigs. Each pen had 3 or 4 barrows or gilts, except for 1 pen in the ZnAA treatment, which contained all barrows. The pigs were maintained on the same Zn dietary treatment as their dam. There were unequal replicates in each treatment (9, 8, and 12, for diets 1, 2, and 3, respectively) because of the unequal number of pigs available.
During the nursery period, pigs were housed in total confinement in an environmentally controlled modular building in 0.97 x 1.47 m pens on plastic, slotted floors and with an under-floor flush system. Each pen had a stainless steel, gravity-fed, 4-hole feeder, and 1 nipple waterer. The feed and water were provided ad libitum throughout the experiment.
Tissue and Bone Collection and Analyses
At weaning and at the end of phase III, 1 gilt per replicate was randomly selected for tissue collection and analyses. One replicate in the ZnAA treatment during the nursery phase contained only barrows, so only the 11 replicates with gilts were used. Each gilt was killed by carbon dioxide inhalation. The left front foot, liver, pancreas, and the entire small intestine were removed from each pig. The left front foot, liver, and pancreas were frozen and stored until further analyses.
After the small intestine was removed from the pig, it was rinsed with saline to remove the digesta and then weighed. After weighing, it was divided into 3 sections: the duodenum, the jejunum, and the ileum. A 5-cm segment was removed from the median of each section (duodenum, 15 cm caudal to the pylorus; jejunum, 60 cm cranial to the ileocecal junction; and ileum, 10 cm cranial to the ileocecal junction), and then these segments were stored in plastic jars containing 100 mL of formalin. The segments were allowed to fix in the formalin for 7 d before further analysis.
The segments of the 3 small intestinal sections were embedded in paraffin, and then a rotary microtome was used to cut 5-µm-thick cross-sections from each segment. Two sections of each intestinal segment from each pig were mounted on a polylysine-coated slide and then stained with hematoxylin and eosin (Carson, 1997). The villus height (the apex of the villus to the villus-crypt junction), villus width (width of the villus at one-half of the villus height), and crypt depth (villus-crypt junction to the base of the crypt) for each sample were measured with a light microscope (Nikon Model 030532, San Francisco, CA). As many as 10 individual digital images (with a minimum of 5) were taken, and the images were digitized using the Scion Imaging software and camera (Spot Insight color digital, version 3.4, Diagnostics Instruments Inc., Sterling Heights, MI) for measurement.
The second and third metacarpal bones of each foot were removed, manually cleaned of adhering tissue, and used for determination of bone breaking strength using an HD 250 Texture Machine (Texture Technologies Corporation, Scarsdale, NY) fitted with a 3-point bend rig with a load cell capacity of 50 kg, a cross-head speed of 100 mm/min, and a span over which the bone was set of 1.5 cm. After determination of the bone breaking strength, fat was removed from the bones by Soxhlet extraction for 72 h (36 h in ethanol followed by 36 h in diethyl ether) and then dried at 100°C for 24 h. Bone ash percentage was determined by placing the bones in a muffle furnace and ashing for 36 h at 550°C (AOAC, 2003). The bones were then solubilized with reagent grade sulfuric acid, heated, diluted to a fixed volume, and analyzed for Zn and Cu concentrations. The liver and pancreas of each pig were wetashed in nitric acid and hydrogen peroxide, and then analyzed for Zn and Cu concentrations (AOAC, 2003). Mineral content was determined by inductively coupled plasma emission spectroscopy (Model Optima 3000, Perkin Elmer, Norwalk, CT).
The response variables during gestation were parity; initial, d 80 and d 110 of gestation sow BW; and ADG, ADFI, and G:F from d 15 to 110 of gestation. The sow response variables during lactation were parity; days of gestation; days from d 110 of gestation to farrowing; weaning weight; lactation ADFI; lactation length; pigs born alive, dead, and total; and litter and average pig birth weight. The litter performance response variables included pigs nursed and weaned after cross-fostering; total and average pig weaning weight; litter and pig ADG; and percent pig survival. The litter intestinal and tissue response variables included BW of the pig selected for tissue collection; small intestinal wet weight; villus height and width, and crypt depth, of the duodenum, jejunum, and ileum; bone breaking strength; and bone, liver, and pancreas Zn and Cu concentrations. The response variables for the nursery period included ADG, ADFI, and G:F for phases I, II, and III; BW of all pigs and the pig selected for tissue analyses; small intestinal wet weight; villus height and width, and crypt depth, of the duodenum, jejunum, and ileum; bone breaking strength; and bone, liver, and pancreas Zn and Cu concentrations.
Statistical Analysis
Data collected during gestation were analyzed by ANOVA appropriate for a randomized complete block design using the GLM procedures of SAS (SAS Inst. Inc., Cary, NC), with treatment and replicate in the model. The pen of sows served as the experimental unit.
Data collected during lactation, including weanling pig tissue data, were analyzed by ANOVA for a completely randomized design using the GLM procedures of SAS. The individual sow was the experimental unit for all data. Data were analyzed without a covariate with the following exceptions. Sow d 110 of gestation BW was a covariate for sow weaning weight, and it was significant (P < 0.05) as a covariate for this response variable. Lactation length was a covariate for lactation total and ADFI, litter weaning weight and ADG, average pig weaning weight and ADG, and percent pig survival; lactation length was significant (P < 0.05) as a covariate for lactation and total ADFI and litter and average pig weaning weights.
Data collected during the nursery phases were analyzed by ANOVA for a completely randomized design, and initial BW of the pigs entering the nursery was used as a covariate for all response variables because there were differences among treatment in initial weight. The pen of pigs served as the experimental unit for all response variables.
Treatment means were separated with the PDIFF option of SAS. Treatment differences were considered significant at 
= 0.10 if the overall treatment effect was P = 0.10. Data are presented as least squares means.
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RESULTS |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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). During lactation, sows fed ZnSO4 had a longer gestation length (P < 0.05; Table 3) in contrast to sows fed the control diet, with sows fed ZnAA being intermediate. Because of the greater gestation length, sows fed ZnSO4 had a shorter lactation length (P < 0.05) than those fed the control diet. Parity was not different among sows fed any diet (P > 0.10). Diet did not affect sow weight at weaning, lactation ADFI, or pigs born alive, dead, or total.
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The weaned pig weight of those pigs selected for tissue collection (P < 0.05) and the wet weight of the small intestine (P < 0.10) were greater (Table 4) in pigs from sows fed the control diet compared with those from sows fed ZnSO4. However, when intestine weight was expressed per kilogram of BW, there was no effect of treatment (P > 0.10). Villus height of the jejunum of pigs from sows fed ZnSO4 or ZnAA was greater (P < 0.05) than those from sows fed the control diet. Pigs from sows fed ZnAA had greater (P < 0.10) liver Cu concentrations than pigs from sows fed the control or ZnSO4 diets.
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). Pigs fed ZnSO4 had greater duodenal villus width (P < 0.05; Table 6) than those fed ZnAA, and pigs fed ZnSO4 or the control had greater ileal villus width (P < 0.05) than those fed ZnAA. There was no effect of diet (P > 0.10) on final BW of the pigs selected for tissue collection or small intestine wet weight. Pigs fed either ZnSO4 or ZnAA had greater (P < 0.05) bone Zn concentrations than those fed the control diet. Pigs fed the control diet had greater (P < 0.05) bone Cu concentrations than those fed ZnAA. Liver Zn concentration was greatest (P < 0.05) in pigs fed ZnSO4, followed by those fed ZnAA (P < 0.05), and then in those fed the control diet. Pancreas Zn concentration was greater (P < 0.05) in pigs fed ZnSO4 than in those fed the control diet. Bone breaking strength and liver and pancreas Cu concentrations were not affected by diet.
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DISCUSSION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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; Favier, 1992; Bedwal and Bahuguna, 1994). Additionally, Zn has been suggested to be required by the fetus for support of cell proliferation and tissue differentiation of developing organs (Hostetler and Kincaid, 2004). These effects of Zn on the fetus make Zn nutrition during gestation and lactation especially important because the sow must provide the necessary nutrients to support growth and development of the fetus and pig. The sow’s trace element body reserves have been shown to serve as a pool for meeting the nutrient requirements of the fetus, but it is not clear if these stores can support the fetus completely (Mahan and Vallet, 1997).
There are numerous reports regarding the effect of Zn on pigs, but we are aware of only one report comparing inorganic and organic Zn sources in sows during gestation or lactation and the subsequent effects on the pig. Caine et al. (2001) reported that ZnAA fed from d 80 of gestation to farrowing had a positive effect on intestinal development and immune function in pigs 24 h after being weaned at 14 d of age. These researchers did not report data on pigs during the nursery period.
We observed no effect of additional Zn supplementation on sow weight or ADFI during gestation. There was an increase in litter birth weight that was due to a numerical increase in total pigs born for sows fed ZnAA. After farrowing, sows fed ZnAA nursed and weaned more pigs per litter with no difference in pig weaning weight. As mentioned earlier, every attempt was made to adjust each litter to 10 pigs per sow within treatment, and these attempts were successful for the control and ZnSO4 treatments. However, in the ZnAA treatment, the sows nursed more pigs because of the increased number of pigs born per sow and the limited space for cross-fostering. Although the primary objective was to evaluate progeny responses to Zn supplements to the sow, the responses observed in the sow are interesting, even with the limited number of observations. The increase in litter birth weight due to more total pigs born and born alive with no change in average pig or sow weaning weight suggests that sows fed ZnAA made more efficient use of nutrients than sows fed the other diets.
Additional Zn supplementation during the nursery period did not affect growth performance. Our data agree with those of other researchers (Hill et al., 1986; Swinkels et al., 1996; Cheng et al., 1998; van Heugten et al., 2003, Buff et al., 2005) who also report no effect of various organic Zn sources or levels of inclusion on nursery pig growth performance. However, other researchers have reported positive effects of organic Zn sources on nursery pig growth performance (Ward et al., 1996; de Rodas et al., 1999; Hollis et al., 2005). Some of these researchers used a design similar to ours, wherein the additional Zn was added to a basal diet that contained supplemental Zn; others added Zn to a basal diet that contained no supplemental Zn. The response or lack thereof to organic Zn sources was not dependent on whether the basal diet was supplemented with Zn.
Supplemental dietary Zn had various effects on the small intestine. Jejunum villus height of weanling pigs from sows fed ZnSO4 or ZnAA was greater than those from sows fed the control diet. However, in the nursery pig, there were no effects of supplemental Zn on morphology of the jejunum. Villus width of the duodenum and ileum of pigs fed ZnSO4 were greater compared with those fed ZnAA. These variable intestinal responses are difficult to explain. Although intestinal morphology and intestinal Zn concentration may not be related, Swinkels et al. (1996) and Cheng et al. (1998) reported no difference in intestinal Zn concentration in pigs fed ZnSO4, ZnLys, or a Zn chelate. Cheng et al. (1998) also reported no difference in the percentage of Zn absorbed from the small intestine regardless of Zn form (ZnSO4 or ZnLys) or supplementation concentration (0 or 100 ppm).
There were no differences in bone, liver, or pancreas Zn concentrations in pigs immediately after they were weaned, but pigs fed either ZnSO4 or ZnAA during the nursery phase had greater Zn in all 3 tissues in contrast to those fed the control diet. Bone breaking strength was not affected by diet at weaning or at the end of the nursery period. The bone Zn data from this experiment agree with Hill et al. (1986), who reported that bone Zn was increased with no change in bone breaking strength (referred to as peak force) when nursery pigs were fed ZnSO4 or ZnAA. The liver Zn data from this experiment agree with Cheng et al. (1998). However, the data do not agree with van Heugten et al. (2003), who reported no differences in liver or pancreas Zn concentrations when pigs were fed 0 or 80 ppm supplemental Zn from ZnSO4, ZnLys, or ZnMet (their control diet contained 80 ppm Zn).
We have no explanations for the increase in liver Cu of weanling pigs from sows fed ZnAA. Liver Cu also was numerically increased in pigs fed ZnAA after the nursery phase. Although we are aware of the potential interactions of Zn and Cu, the effects reported herein seem to be independent of liver Zn concentrations. Swinkels et al. (1996) and Cheng et al. (1998) reported greater liver Zn and lower liver Cu levels in pigs supplemented with ZnSO4 or organic Zn (ZnMet or ZnLys) relative to those fed a control diet. Although the liver Zn results of our trial agree with these authors, the liver Cu levels reported herein are not in agreement as liver Cu was greatest in pigs fed ZnAA, and levels in pigs fed the control or ZnSO4 were not different.
These data suggest that sows fed diets supplemented with additional ZnAA may be able to better provide for their fetuses during times of important developmental changes, thus resulting in increased pigs born and weaned per litter. However, there seems to be very little difference in ZnSO4 or ZnAA on growth performance or intestinal development in pigs after weaning.
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Footnotes |
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2 The authors thank K. C. Klasing and the Univ. of California at Davis for assistance with the histological analyses. The authors also would like to thank T. O’Conner-Dennie, M. Roux, A. R. Jackson, B. K. Perkins, M. A. Persica, D. W. Dean, J. L. Shelton, and R. D. Lirette, and the Louisiana State Univ. Agric. Center Swine Unit for assistance with data collection and analyses.
3 Current addresss: Degussa Corporation, 1701 Barrett Lakes Blvd., Suite 340, Kennesaw, GA 30144.
4 Corresponding author: rob.payne{at}degussa.com
Received for publication October 31, 2005. Accepted for publication March 29, 2006.
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LITERATURE CITED |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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