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This research was conducted to evaluate the effects of sows supplement different selenium sources on the growth performance of suckling pigs and discussed the mechanism through Se contents and antioxidant system function of serum, tissues and milk, key metabolism enzymes activities, GSH-Px gene expression, secretion of related hormones, immune indexs and organ morphology.Twelve healthy sows (Landrace X Yorkshire) in late pregnancy with same parity were randomly divided into two groups according to experiment requirement, The control group was fed basal diet supplement with sodium selenite, as did the experimental group with DL-Selenomethionine, the amounts calculated by selenium were 0.3mg/kg each. The feeding trial lasted for 60d. At the end of the feeding trial, one pig (female) was selected based on similar body weight for slaughter experiment. The main results were as follows:1. The results of feeding experiment indicated that compared with the sodium selenite group, adding DL-selenomethionine in sows feed improved the weaning litter weight, weaning weight, average daily gain and milk ability by 8.00% (P<0.05), 9.93%(P<0.05),12.20%(P<0.05) and 10.06%(P<0.05), respectively.2. The results of slaughter experiment indicated that adding DL-selenomethionine significantly increased the thymus index comparing with the sodium selenite (P<0.05).3. Histomorphometry indicated that compared with the DL-selenomethionine group, in the sodium selenite group, the shape of liver cells and pancreatic cells shrinked, membrane dissolved mildly, organelle within the cytoplasm reduced, disordering, the nuclear membrane folded, double structure of membrane was not obvious, partial ablation appeared, chromatin marginated and condensed, the mitochondrial swelled, membrane dissoluted, the crest reduced, some crest disappeared, net pool of endoplasmic reticulum increased, dissoluting partially, expansing and vesicling.4. Results of Se content indicated that adding DL-selenomethionine in sows feed, selenium content in serum of sows and its suckling pig, and in liver, kidney, pancreas, muscle, thymus and thyroid of the suckling pigs, colostrum and 7th,14th,21th,28th milk improved significantly(P<0.05), respectively.5. Function tests of the antioxidant system revealed that:(1) supplementation of DL-selenomethionine sifnificantly increased T-AOC in serum of sow, T-AOC and GSH-Px activity in colostrum and milk, SOD activity in colostrum and 14d,21d milk, GSH content in colostrum and 14d,21d and 28d milk (P<0.05), respectively, while decreased MDA content in serum and milk of sow (P<0.05), (2) adding DL-selenomethionine sifnificantly improved, in suckling pigs, T-AOC and GSH-Px activity of liver, kidney, pancreas and muscle, SOD activity of serum, pancreas and muscle, GSH content of serum, kidney, pancreas and muscle (P<0.05), while decreased MDA content of liver, kidney and pancreas (P<0.05), respectively.6. Results of hormone test showed that adding DL-selenomethionine significantly increased the serum TT3 level (P<0.05) while decreased level of TT4and Glu, and the ratio of TT4 to TT3, and that of Glu to Ins (P<0.05), respectively.7. Results of digestive enzymes showed that adding DL-selenomethionine sifnificantly increased activitives of trypsin, lipase and amylase of pancreas (P<0.05), respectively.8. Results of immune indexs test showed that adding DL-selenomethionine have no significant defference for content of IgA, IgG, IgM in serum of suckling pigs compared with the sodium selenite (P>0.05).9. The experimental results of the molecular biology revealed that adding DL-selenomethionine significantly increased the GSH-Px mRNA abundance of the pancreas of suckling pigs by 28.13%(P<0.01) than the sodium selenite.Results above indicated:compared with the sodium selenite, adding DL-selenomethionine could significantly increase selenium level and antioxidant function of milk, promoting the tissue deposition of selenium of suckling pigs, gene expression of the antioxidant enzyme and hormone secretion, enhancing antioxidative function of body and secretion of digestive enzymes, improving health and metabolism of suckling pigs, finally result in growth-promoting effects for suckling pigs.
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