Effects Of Yeast Extract On Growth Performance,Antioxidant And Immune Function,and Gut Microbiota Of Weaned Piglets And Mice

It is urgent to develop some green additives as substitutes for antibiotics to meet the challenge of pig raising without antibiotics.In this study,the effects of yeast extract on growth performance of weaned piglets were studied by adding different concentrations of yeast extract.On this basis,the regulation mechanism of yeast extract promoting animal growth by affecting antioxidant and immune function and intestinal microbial composition was preliminarily explored with weaned mice as a model.1.Effects of yeast extract on growth performance of weaned piglets.Weaned piglets were selected according to the principle of similar parity,weaning age and body weight,and the effects of adding 0.75%,1% and 2.5% yeast extracts on growth performance of weaned piglets were studied.Compared with the control group,adding 1% yeast extract could significantly increase the average daily gain of piglets(P<0.01)and significantly reduce the diarrhea rate of piglets(P<0.05).Adding 2.5% yeast extract could significantly increase the average daily gain of piglets(P<0.01),and significantly reduce the ratio of feed to gain and diarrhea rate of piglets(P<0.01).2.Effects of yeast extract on growth performance,antioxidant and immune function and intestinal microbe in mice.Thirty six C57 BL/6J wild-type mice aged about 21 days were randomly divided into three groups according to body weight: control group,1% experimental group and 2.5% experimental group.(1)Compared with the control group,adding 1% and 2.5% yeast extract could significantly increase the average daily gain of weaned mice(P<0.05)and significantly reduce the ratio of feed to gain(P<0.05).The gastrocnemius index,colon length,villus length of duodenum and jejunum and the ratio of villus length to crypt depth of whole small intestine were significantly increased(P<0.05),and ileum crypt depth was significantly decreased(P<0.05).The addition of 2.5% yeast extract could also significantly increase the quadriceps femoris index,tibialis anterior muscle index,liver index,intestinal length as well as the activities of lipase,trypsin and cellulase of the small intestine(P<0.05)and significantly reduce the crypt depth of whole small intestine(P<0.05).(2)Compared with the control group,the addition of 2.5% yeast extract could significantly improve the total antioxidant capacity in serum and significantly reduce the content of malondialdehyde in liver(P<0.05).The addition of 1% yeast extract had no significant effect on antioxidant level of mice(P>0.05).The addition of 1% yeast extract could significantly increase serum IFN-γ level(P<0.01),while the addition of 2.5% yeast extract could significantly increase serum Ig G and IFN-γ level(P<0.01).(3)The addition of yeast extract can change the intestinal microbial structure of mice.At the phylum level,compared with the control group,the addition of 1% and2.5% yeast extract could significantly reduce the abundance of Verrucomicrobia(P<0.05),and the addition of 2.5% yeast extract could significantly increase the abundance of Firmicutes(P<0.05).At the genus level,compared with the control group,the addition of 1% and 2.5% yeast extract could significantly reduce the abundance of Prevotella and Akkermansia(P<0.05),the addition of 2.5% yeast extract could also significantly reduce the abundance of Odoribacter and Mycoplasma(P<0.05)and significantly increase the abundance of Allobaculum(P<0.05).Yeast extract can promote the healthy growth of the body by increasing the abundance of bacteria that contribute to muscle development(such as Firmicutes and Allobaculum),reduceing the abundance of bacteria that are negatively associated with muscle development(such as Verrucomicrobia)and weight gain(such as Prevotella 、Akkermansia and Odoribacter)and are harmful to the gut(such as Mycoplasma).In conclusion,the yeast extract can promote digestion and absorption of nutrients by improving the enzyme activity of small intestinal and promoting the development of intestinal villi,thus promoting the weight gain of piglets and mice.It can also regulate the structure of intestinal flora,improve the antioxidant level and immune function of the body,and then improve the growth performance of weaned piglets and mice.