营养限制与补偿对蒙古育成羯羊肝脏关键酶活性的影响

Feed Restriction and Realimentation Affect Activities of Hepatic Key Enzymes in Mongolia Growing Wethers

本试验旨在阐明营养限制与补偿对蒙古育成羯羊肝脏关键酶活性的影响。试验选用40只平均体重为(14.72±1.10)kg的3月龄蒙古育成羯羊,随机分为对照组(CG)和双限组(RG)。试验分营养限制期(60d)和营养补偿期(90d)。限制期2组饲粮对应能氮水平为代谢能(ME):10.88(对照组)和8.62(双限组)MJ/kg;粗蛋白质(CP):15.0%(对照组)和5.7%(双限组)。补偿期各组饲喂同一能氮水平(ME:9.75 MJ/kg;CP:12.0%)的饲粮。在限制期与补偿期末分别测定蒙古育成羯羊肝脏中己糖激酶(HK)、丙酮酸激酶(PK)、乳酸脱氢酶(LDH)、果糖-1,6-二磷酸酶(FBP1)、苹果酸脱氢酶(MDH)、α-磷酸甘油脱氢酶(GAPDH)、丙氨酸转氨酶(ALT)、天冬氨酸转氨酶(AST)和谷氨酸脱氢酶(GLDH)的活性。结果显示:限制期结束时双限组蒙古育成羯羊肝脏中HK、ALT、AST、GLDH活性显著低于对照组(P<0.05),而PK、LDH、FBP1、MDH、GAPDH活性显著高于对照组(P<0.05);经过90d补偿后,双限组蒙古育成羯羊肝脏中HK、PK、MDH、ALT活性显著高于对照组(P<0.05),而LDH、FBP1、GAPDH、AST、GLDH活性与对照组差异不显著(P>0.05)。结果提示,限制期双限组蒙古育成羯羊糖酵解途径关键酶活性降低,糖异生途径关键酶活性升高,脂肪分解途径关键酶活性升高,这与机体在低能氮营养水平时脂肪动员加强有关,蛋白质代谢途径关键酶活性降低则表明限制期蛋白质代谢降低;补偿期双限组蒙古育成羯羊总体糖酵解、糖异生和脂肪分解途径关键酶活性基本恢复到对照组水平,而PK活性显著提高,脂肪合成和蛋白质代谢途径关键酶活性升高可能与此期较高的生长速率相关。

This experiment was conducted to study the effects of feed restriction and realimentation on the activities of hepatic key enzymes in Mongolia growing wethers.Forty three-month-old growing wethers with an average body weight of(14.72±1.10) kg were selected and divided into 2 groups(control group and restricted group).The feeding trial included a 60-d feed restriction period and a 90-d feed realimentation period.The metabolizable energy(ME) and crude protein(CP) content in diets were 8.62 MJ/kg and 5.7% for restricted group and were 10.88 MJ/kg and 15.0% for the control group during the feed restriction period.All growing wethers were offered the same diet(ME: 9.75 MJ/kg;CP: 12%) during the feed realimentation period.At the end of feed restriction and realimentation period,the activities of hexokinase(HK),pyruvate kinase(PK),lactate dehydrogenase(LDH),fructose-1,6-bisphosphatase(FBP1),malate dehydrogenase(MDH),α-glycerophosphate dehydrogenase(GAPDH),alanine aminotransferase(ALT),aspartate aminotransferase(AST) and glutamate dehydrogenase(GLDH) in liver in each group were examined.The results showed that the activities of hepatic HK,ALT,AST,GLDH of restricted group were significantly lower than those of the control group(P<0.05) at the end of feed restriction period,while the activities of PK,LDH,FBP1,MDH and GAPDH of restricted group were significantly higher than those of the control group(P<0.05).At the end of realimentation period,the activities of hepatic HK,PK,MDH and ALT of restricted group were significantly higher than those of the control group(P<0.05),while the activities of LDH,FBP1,GAPDH,AST and GLDH showed no significant differences(P>0.05).These results indicate that the activities of key enzymes in the glycolysis and protein metabolism are decreased,and the activities of key enzymes in gluconeogenesis and lipolysis are increased.That may be related to the strengthening of fat mobilization during the feed restriction period.The activities of key enzymes in protein metabolism are decreased which means to decrease protein metabolism during the feed restriction period.At the end of realimentation period,the activities of key enzymes in glycolysis,gluconeogenesis and lipid metabolism are recovered to the level of control group,while the activities of hepatic PK and key enzymes in fat synthesis and protein metabolism of control group are significantly higher,this may be related to the higher growth rate during the restriction period.