Study On Improving Production Performance And Mechanism Of Nursery Pigs By Tannic Acid

Tannic acid is a complex polyphenolic compound that is commonly found in many plants.Natural tannins can be divided into two types:hydrolysable tannic acid and condensed tannic acid.Hydrolysable tannic acid is the most widely used in animal production.In livestock and poultry breeding,the long-term use of antibiotics to prevent disease and improve productivity is common,which have leads to resistance to pathogens.The drawbacks such as it remain in the animal bodies and affect the health of human and animals are also attracting people's attention,especially causes the whole animal husbandry to attach great importance to it.Limiting or reducing the use of antibiotics as feed additives is the basis for the healthy development of feed and aquaculture industry,and is also the inevitable trend of the development of human society.The search on alternative antibiotics has become a hot spot in current research.In this study,the effects of different dose tannins in diet on the growth performance of pigs were studied.At the same time,the effects of tannic acid on the activation of intestinal digestive enzyme,intestinal structure and inflammatory factor were analyzed.120 healthy weaned piglets were randomly divided into 4 parts:30 pigs in each part(3 replicates and 10 in each group).Every part divided into three groups:blank control group,low dose group(100mg/kg),middle dose group(200mg/kg)and high dose group(400mg/kg).The average daily gain(ADG),average daily intake(ADI),feed/meat ratio and diarrhea rate were measured at 2 weeks and 4 weeks after the experiment.The contents of trypsin,pancreatic lipase and amylase activity were determined by collecting duodenal mucus.qPCR was used to detect the expression of inflammatory factor,gastric mucus was collected to determine pepsin activity,duodenum was collected,tissue sections were stained with HE and intestinal villi height was measured.The results showed that(1)after the second week of feeding,there was no significant difference in feed intake among the four groups.The daily gain and feed/meat ratio of the three groups were significantly higher than those of the blank group,and the difference of daily gain among the three groups was not significant.In diarrhea rate,in tannic acid 100 mg/kg group,tannic acid 200 mg/kg,tannic acid 400 mg/kg were significantly lower than control group,but in tannic acid 200 mg/kg was more significant difference in tannic acid 100mg/kg group.(2)at the 4th week,in tannic acid 100 mg/kg,tannic acid 200 mg/kg,tannic acid 400mg/kg significantly increased the daily intake of preserved pigs.The daily gain and feed/meat ratio of preserved pigs were also significantly increased,and tannic acid 100 mg/kg,tannic acid 200mg/kg was significantly lower than that of the control group,but there was no significant effect between the tannic acid 400 mg/kg and the blank group.The diarrhea rate of tannic acid 100 mg/kg group and tannic acid 200 mg/kg group were significantly lower than that of blank group,but there was no significant difference in tannic acid 400 mg/kg group.The results showed that in 400 mg/kg of 100 mg/kg tannic acid group had no significant effect on pepsin for 2 weeks and 4 weeks.The activity of amylase was significantly increased by tannic acid 100 mg/kg.There was no significant change in the activity of amylase at 400 mg/kg.The activity of lipase and trypsin was significantly increased by tannic acid 100 mg/kg,while the activity of lipase was decreased by 200 mg/kg,but there was no significant difference after 4 weeks.Different doses of tannic acid could increase the activities of amylase,lipase and trypsin in different digestive enzymes for 2 weeks,and the addition of 100 mg/kg had the best effect on the activity of amylase,lipase and trypsin.It could promote the secretion of 100 mg/kg and 400 mg/kg of intestinal mucosal secretory immunoglobulin(sIgA).The length of villus of intestinal villus were significantly increased(P<0.05)in the 200mg/kg?400mg/kg tannic acid group(P<0.05).The length of villus and the depth of crypt had no significant difference between the control group and the control group.Therefore,adding gallnut tannic acid to the diet of nursery pigs can improve its performance,increase digestive tract enzyme activity,enhance intestinal structure and mucosal immune function,and consider two weeks of 100mg/kg supplementation.