| Decreasing dietary crude protein(CP)content properly while supplemented with lysine,methionine,threonine and tryptophan to meet the NRC requirement can improve growth performance or keep it steady.Thus,it is increasingly popularized in porcine industry as an efficient strategy for optimizing diet amino acids ratios,increasing nitrogen utilization,decreasing nitrogen excretion,reducing nitrogen pollution of the environment.This study aimed to evaluate the effect of low-protein diets on gut morphology and both digestive and absorptive functions in weaned piglets,growing pigs and finishing pigs.Pigs in different growing stage were randomly assigned to one of these three experimental groups,individually:1)Normal protein diet(based on the NRC standard,2012);2)Medium protein diet(reduced 3%CP based on the NRC standard,2012),supplemented with lysine,methionine,threonine and tryptophan to meet the NRC requirement;3)Low protein diet(reduced 6%CP based on the NRC standard,2012),supplemented with lysine,methionine,threonine and tryptophan to meet the NRC requirement.This study aimed to evaluate the effect of low-protein diets on gut morphology and functions in different growing stage of pigs.This thesis focuses on the following parts,1 Effect of low-protein diets on gut morphology,digestive enzymes and serum biochemical indicators in weaned pigletsIn this study,a total of 54 cross-bred Duroc x(Landrace x Large White)(9.58 ±0.62kg,all pigs were weaned at 28d)piglets were randomly assigned to one of these three experimental groups,individually:20%CP group(NRC standard,2012),17%CP group and 14%CP group both supplemented with lysine,methionine,threonine and tryptophan to meet the NRC requirement,respectively.Six piglets were randomly selected and slaughtered in each group on experimental day 10,25,45.Tissue samples of duodenum,jejunum and ileum of piglets on day45 were collected to measuring the villus height and crypt depth.The pH value and activity of trypsin and lipase in gut lumen contents and pancreas in piglets were investigated.The serum concentrations of total protein,albumin,globulin,glucose,urea nitrogen,total cholesterol,triglyceride were assayed by ELISA method,individually.The results were as follows,piglets on experimental d10,when compared with 20%CP group,the pancreas lipase activity was significantly decreased in 14%CP group(p<0.05).Piglets on experimental day25,When compared with 14%CP group and 20%CP group the jejunum lipase activity was significantly increased in 17%CP group(p<0.05).The ileum trypsin activity was significantly decreased in 14%CP group(p<0.05)when compared with 20%CP group.When compared with 20%CP group,both the serum urea nitrogen and the glucose content were significantly decreased in 14%CP group and 17%CP group(p<0.05).When compared with 17%CP group and 20%CP group,the serum triglyceride content was significantly increased in 14%CP group(p<0.05).Piglets on experimental day45,the villus height of duodenum in piglets were significantly decreased in 14%CP group and 17%CP group when compared with 20%CP group(p<0.05).the villus height of jejunum were significantly decreased in 14%CP group when compared with 17%CP group and 20%CP group(p<0.05).When compared with 20%CP group,the pancreas lipase activity was significantly decreased in 14%CP group(p<0.05).When compared with 20%CP group,the ileum pH value was significantly decreased in 14%CP group(p<0.05).When compared with 20%CP group,the serum urea nitrogen content was significantly decreased in 14%CP group and 17%CP group(p<0.05).When compared with 17%group and 20%group,the total cholesterol and triglyceride content were significantly increased in 14%CP group(p<0.05).Collectively,these results indicated that the villus height of duodenum as well as the urea nitrogen content were significantly decreased when the CP decreased 3%.The villus height of duodenum and jejunum,trypsin and lipase activity,serum glucose content were significantly decreased while the total cholesterol and triglyceride content were significantly increased.2 Effect of low-protein diets on gut morphology,digestive enzymes and serum biochemical indicators in growing pigs.Eighteen growing pigs(36.53±1.68kg)were randomly assigned to one of these three experimental groups,individually:18%CP group(NRC standard,2012),15%CP group and 12%CP group both supplemented with lysine,methionine,threonine and tryptophan to meet the NRC requirement,respectively.After 30 days,all pigs were slaughtered.Tissue samples of duodenum,jejunum and ileum were collected to measuring the villus height and crypt depth.The pH value and activity of trypsin and lipase in gut lumen contents and pancreas in pigs was investigated.The serum concentrations of total protein,albumin,globulin,glucose,urea nitrogen,total cholesterol,triglyceride were assayed by ELISA method,individually.The results showed that there were no obvious effects on villus height and crypt depth of the gut in growing pigs(p>0.05).Trypsin and lipase activity and pH value were no significantly changed in all three groups(p>0.05).When compared with 18%CP group,the serum urea nitrogen content was significantly decreased in 12%CP group and 15%CP group(p<0.05).The serum glucose,total protein,albumin protein,globulin,triglyceride,total cholesterol content were not statistical significance(p>0.05).Collectively,these results indicated that the serum nitrogen content was significantly decreased while no significant effects were fund in gut mophorlogy,digestive enzymes activity,other serum biochemical indicators.3 Effect of low-protein diets on gut morphology,digestive enzymes and serum biochemical indicators in finishing pigs.Eighteen finishing pigs(62.28 ± 2.15kg)were randomly assigned to one of these three experimental groups,individually:16%CP group(NRC standard,2012),13%CP group and 10%CP group both supplemented with lysine,methionine,threonine and tryptophan to meet the NRC requirement,respectively.After 50days,all pigs were slaughtered.Tissue samples of duodenum,jejunum and ileum were collected to measuring the villus height and crypt depth.The pH value and activity of trypsin and lipase in gut lumen contents and pancreas in pigs was investigated.The serum concentrations of total protein,albumin,globulin,glucose,urea nitrogen,total cholesterol,triglyceride were assayed by ELISA method,individually.The results showed that when compared with 13%CP group and 16%CP group the crypt depth was significantly decreased in 10%CP group in rowing-finishing pigs(p<0.05).When compared with 13%CP group and 16%CP group,the pancreas lipase activity was significantly increased in 10%CP group(p<0.05).The pH and pancreas trypsin activity,the trypsin and lipase activity in jejunum and ileum were not significantly changed(p>0.05).When compared with 13%CP group and 16%CP group,the serum urea nitrogen content was significantly decreased in 10%CP group(p<0.05).The serum glucose,total protein,albumin,globulin,triglyceride,total cholesterol content were not statistical significance(p>0.05).Collectively,these results indicated that the serum nitrogen content was significantly decreased when the CP decreased.The crypt depth of ileum significantly decreased while no significant effects were fund in digestive enzymes activity and other serum biochemical indicators when the CP decreased 6%. |
PDF Full Text Request