Effects Of Weaning Age And Neutral Protease On The Performance, Digestive Enzyme Activities And Growth Of Digestive Organs In Weaned Piglets

The purpose of the research was to study the effects of weaning age and neutral protease on the performance,digestive enzyme activities and growth of digestive organs in weaned piglets.The experiments were compared the differences of the weights of stomach, pancreas and liver,the content of DNA,RNA and protein in small intestinal mucosa and pancreas,and the activities of trypsin,pancreatic lipase,amylopsin and alkaline phosphatase in the jejunum and pancreas on the piglet weaned on the 23^rd age and piglet that weaned on the 28^th age,and the piglet weaning on the 23rd age which fed neutral protease,respectively.The experimentⅠ:The crossbred(Duroc×Landrace×Large White) piglet was used as the test animal.Forty-eight piglets were selected from 9 litters and randomly divided to two groups:weaned on the 23^rd age and the 28^th age.Every group takes the samples in 0day, 3day,7day,14day respectively after weaning.The results showed:(1)Weaned on the different day,had prominent influence on production performance of the piglets.2 weeks after weaning,the piglets weaning on the 28^th age increases ADG having improved by 93.29%than that of the piglet weaning on the 23^rd age, the ADFI of piglet weaning on the 28^th age was higher than that of piglet weaning on the 23^th age notably too.After 2 week of weaning in piglet,ADFI of pigs that weaning on the 28^th age improve 83.45%than that of pigs weaning on the 23^th age;(2) Weaning can promote the growth of piglet's stomach and pancreas.The stomach and pancreas increased 141.5%and 221.14%respectively in 2 weeks after weaning on the 28^th age,while on the piglets weaning on the 23^rd age,these increasing of the stomach and pancreas was only 65.12%and 170.64%in 2 weeks after weaning.The development of the liver was not promoted by the increase of weaning age(P＞0.05);(3) The growth of the intestinal length had the similar trend after the piglet weaned,the increases of intestine weight(P＜0.05) and length(P＞0.05) in the piglets weaned on the 28^th age were higher than that of the piglets weaned on the 23^rd age;(4)The pancreas and jejunum protein,DNA and RNA density in pigs weaned on the 23^rd age were lower than that of pigs weaned on the 28^th in the same period age,but the difference was not significant(P＞0.05);(5) The jejunum AKP activity of pigs weaned on the 23rd age was higher than that of pigs weaned on the 28^th age notably (P＜0.05);(6) Basically identical that different trypsin activity of pigs with weaning age changes the trends after the pig weaning,protease of pancreas of pig weaning on the 28^th age resumes time longer(P＞0.05);The amylase activity of piglet's pancreas presents the similar ascending law to wean on day age differently(P＜0.05),indicate piglet to be pancreas amylase secretion ability stability relatively heavy,wean into influence for will it be age day basically;It influences increasing and dropping with day age that the pancreatic lipase activity of piglet's pancreas is weaned(P＜0.05).Various digestive ferment activity of piglet weaned on the 28th age are higher than the 23rd of the same period age piglets in 2 weeks after weaning(P＜0.05).The experimentⅡ:The crossbred(Duroc×Landrace×Large White) piglet which weaning on 23rd age was used as the test animal.Forty-eight piglets were chose from 9 litters and randomly divided into three groups(n=4 each group,repeated 4 times),and fed with a commercial starter diet(control) and the same diets supplemented with neutral protease(15000U/kg,30000U/kg).The sampling time was at 7 days and 14days respectively after weaning.And the growth performance was recorded at the same time of sampling.The results showed:(1) neutral protease supplementation could improve the body weight gain(P＜0.05),feed inake(P＜0.05),but the body weight did not increase with increase of additive quantity of protease,the high dosage adds showing the downward trends of body weight in pigs(P＞0.05).Adding protease had prominent improvement function on the feed conversion ratio(P＜0.05);(2) Except in the group with high dose in which the weights of pancreas,ileum weight and ileum length were lower than the control group notably(P＜0.05).There is no significant influence of neutral protease supplementation on the weight of digestive organs and length of all intestines(P＞0.05);(3) Protein,RNA density and Protein/DNA in pancreas and jejunum mucosa were not effected(P＞0.05),and in the group with 15000U/kg neutral protease,DNA density of distal jejunum mucosa is higher than the control group notably(P＜0.05);(4)In this experiment,the activity of alkaline phosphatase in the jejunum mucosa in the groups supplemented with neutral protease were higher than that in the control group,but this increase were not prominent(P＞0.05),the activity of digestive ferment can be improved by supplementing neutral protease(P＜0.05),however,in the high dose the activity of digestive ferment in pancreas and jejunum content had downward trends(P＞0.05).The result showed:in the high dose,supplementing the neutral protease in feedstuff had negative effects on the endogenous digestive ferment secreted by weaned piglet's digestive organs.