Effects Of Dietary Valine Supplementation During Gestation And Lactation On Reproductive Performance,Plasma And Milk Biochemical Indexes Of Sows

This studywas used to determine the effects of dietary valine(Val) supplementation during late gestation or lactation on reproductive performance, plasma and milk biochemical indexes in sows.At 85 d of gestation, a total of 60 primiparous sows(Large White × Landrace) with similar body weights was selected and randomly allotted into two dietary groups(Con or Val group), with 30 sows per groups. Sows were housed in individual crates. After farrowing, sows were further randomly assigned to four treatment groups(Con+Con, Con+Val, Val+Con, Val+Val) using a 2 × 2 factorial experimental design, with 15 sows per group. Piglets were cross-fostered after farrowing to standardize litters to 10 piglets per sows. Sows in the Con+Con and Con+Val groups were fed the control diets during late gestation, but during lactation were fed the control diets and Val-supplemented diets, respectively;Sowsin the Val+Con and Val+Val groups wereboth fed Val-supplemented diets during late gestation, but during lactation were fed the control diets and Val-supplemented diets, respectively. The experiment basal diet is a corn-soybean meal diet for lactating sows, while the Val-supplemented diets were formulated by adding 0.38% of L-Val in the basal diet; the ratio of Val to lyline(Lys) was 0.87. The control diets were supplemented with 0.28% of L-alanine as nitrogen balance; the ratio of Val to Lys was 0.57. The results are as follows:1. Dietary Val supplementation only during late gestationsignificantly increased the average birth weight of piglets, the weaning litter weight, and the average daily gain at d 1-21(P<0.05). However, there were no significant difference in the above indexes by the Val supplementation at lactation, or any interaction effects of Val supplementation and Val supplementation period in these indexes(P>0.05).2.Dietary Val supplementation during late gestation significantly improved the average daily feed intake of sows(ADFI) at d 6-10 of lactation(P<0.05). Dietary Valsupplementation during late gestation or lactation, significantly improved the ADFI of sows at d 1-21 of lactation(P<0.05). However, dietary Val supplementation, either at late gestation or lactation, did not affect the backfat thickness, estrus rate within 7 days after weaning, and the weaning to estrus interval(P>0.05).3. The dietary supplemental Val during late gestation significantly reduced the plasma concentrations of urea nitrogen and glucose at d 110 of gestation, and increased the concentrations of the total protein(P<0.05) and albumin(P<0.01) in plasma of sows at d 110 of gestation. The concentrations of plasma albumin at both d 14 and 21 of lactation, were significantly increased(P<0.05), while the plasma glucose concentration at d 14 of lactation was decreased, by the supplementation of Val during lactation(P<0.05). Dietary Val supplementation during late gestation significantly improved the plasma estradiol level at d 110 of gestation(P<0.05), and had tendency to improve plasma prolactin levels at this age(P=0.07), but did not affect plasma insulin and IGF-1 levels at this age(P>0.05). Dietary Val supplementation during late gestation had no significant effects on the four hormones mentioned above in the plasma at d 14 of lactation. Val supplementation during lactation could significantly increase the plasma prolactin levels at d 14 of lactation(P<0.05). A significant interaction between supplementation period and Val supplementation in plasma IGF-1 levels at d 14 of lactation was observed(P<0.05). The plasma triglyceride concentration was not affected by dietary Val supplementation either at late gestation or lactation period(P>0.05).4. Dietary Val supplementation during late gestation significantly increased plasma Val concentration(P<0.01), and the isoleucine and histidine concentrations in the plasma(P<0.05), but significantly reduced the Lys concentration in the plasma, at d 110 d of gestation(P<0.05). However, dietary Val supplementation during late gestation did not affect the plasma free amino acid concentrations at d 14 of lactation(P>0.05). Supplemental Val to the lactation diet significantly increased the plasma Val concentration(P<0.01), and reduced the plasma glutamate concentration(P<0.05). Dietary Val supplementation during through late gestation to lactation significantly increased the plasma leucine concentration at d 14 of lactation(P<0.05). Dietary Val supplementation during late gestation significantly increased taurine concentration in milk at d 14 of lactation(P<0.05). Val supplementation during lactation significantly increased the milk concentrations of leucine, proline, and citrulline at d 14 of lactation(P<0.05).5. Dietary Val supplementation during late gestation significantly increased the milk protein content(P<0.01), milk fat, and non-fat solids content, in the colostrum(P<0.05), but significantly reduced the lactose content in the colostrum(P<0.05). Dietary Val supplementation during late gestation did not affect milk composition at d 7, 14, or 21 of lactation(P>0.05). Dietary Val supplementation during late gestation can significantly improve the insulin levels(P<0.05), but not IGF-1 levels(P>0.05), in the colostrum. Val supplementation during lactation significantly increased the milk protein, milk fat, non-fat solid content at d 7 of lactation, and milk fat and non-fat solids contents at d 14 of lactation(P<0.05). No significant interaction effect of dietary valine supplementation during late gestation and lactation on the contents of milk components at d 7, 14 and 21 of lactation were detected(P>0.05).In conclusion, dietary Val supplementation increased the average birth weight of piglets, promoted the average daily feed intake of sows during lactation, increased relative hormone levels, and thus improved the milk quality, which resulted in an increased reproductive performance of sows and growth performance of piglets.