Amino Acids And Metabolic Effects Of Weaning Stress On The Muscle Of Piglets

The objective of the study is to investigate changes of energy metabolism and muscle fiber traits in longissimus muscle because of the weaning stress of piglets, so that examine the extent of the negative impact of weaning stress on the body functions arising. The test selected5fossa (6/nest) Landrace×Yorkshire crossbred newborn piglets, feeding breast milk before weaning, feeding based diet after weaning. Randomly selected the piglet of14-day-old,21-day-old and weaning piglets of Id,3d,5d,7d, getting serum and longissimus muscle of piglets. The results are as follows:(1) Compared unweaned piglets, TGF-B1in serum was significantly lower at weaning3d (P<0.05). At weaning5d, the levels IL-1B, IL-10levels were significantly decreased (P<0.05), Weaning7d, each cytokine level comparing the21st unweaned piglets the difference was not significant (P>0.05). In the muscle, the expression of IL-6was increased significantly (P<0.05) at weaning3d, and the expression of TNF-a was significantly increased at weaning7d (P<0.05). IL-15was significantly difference with the14d (P<0.05).It is showed that weaning stress can affect the immune function of piglets.(2) In addition to Cystine, the rest of the15amino acid content showed a significant increase, and reached to highest value at weaning1-day.(P<0.05), decreased significantly at weaning5-day (P<0.05), and then had a gentle increasing trend. When weaning Id, PAT1expression was significantly lower (P<0.05), but SNAT2increased significantly (P<0.05).Weaning3d, PAT1expression level was significantly different to weaning1d (P<0.05). Weaning7d, PAT2expression reached the maximum, and was significantly different to weaning5d (P<0.05).It is indicated that weaning stress can affect the amino acid composition of piglets and the relative expression levels of amino acid transporter genes in piglets.(3) When weaning1d, Ca2+Mg2+ATPase and LDH were increased significantly. Weaning3d, Na+K+ATPase was significantly higher (P<0.05). Weaning7d, muscle glycogen content was significantly higher than weaning3d (P<0.05). Weaning1d, HSP70, UCP3expression was significantly higher (P<0.05). Weaning7d, expression of HSP70was significantly different (P<0.05). Weaning1d, the expression of Sirtl was significantly lower (P<0.05), and the expression of AMPKa was significantly increased (P<0.05). Weaning3d, PPARa had a significant difference (P<0.05). Weaning Id, MYHCI, MYHCIIb, MYHCIIx expression levels were significantly increased (P<0.05). The key genes of muscle fiber types showed a downward trend during weaning3d,5d,7d. It is showed that stress can affect energy metabolism of weaned piglets.(4) From weaning stress on longissimus muscle the results of cell apoptosis could be seen starting from weaning1d, the number of apoptotic cells began to increase, at weaning3d had the maximum number of apoptotic cells, and from the start weaning5d, apoptotic cells started to decrease.It is indicated that stress can cause apoptosis on weaning piglets.The above test results show that the weaning stress may impact energy metabolism and muscle fiber type traits of pigs, and the impact has a period.It provided a theoretical basis to piglets for the future regulation of weaning stress nutrition.