Effects Of γ-aminobutyric Acid Added To Piglets Diet On Growth Performance,Serum Physiological And Biochemical Indexes,and Apparent Digestibility Of Nutrients

As an inhibitory neurotransmitter,γ-aminobutyric acid(GABA)plays an important role in mammalian organisms.It binds to the corresponding receptors and exerts its physiological and biochemical function in mammals,such as regulating the growth hormone secretion,activating the kidney function,improving immunity,promoting the appetite,relieving the stress,and promoting the beneficial bacterial growth.However,the current research on γ-aminobutyric acid in piglets has rarely been reported.Therefore,the aim of this study was to reveal the effects of γ-aminobutyric acid on the growth performance,serum physiological and biochemical indexes,nutrient apparent digestibility and fecal microbiota in piglets.In the present study,96 pigs with a body weight of 15±0.63 kg and similar health conditions were selected and were randomly divided into 4 groups,3 replicates in each group,and 8 piglets per replicate.The control group was fed the normal nursery pig feed,and the other test groups were supplemented with 20 mg/kg,30 mg/kg and 40 mg/kg γ-aminobutyric acid on the basis of the control group.The test period lasted 28 d,and the test was divided into two stages.The first 14 d is the pre-test period and the last 14 d is the post-test period.The results were as follows: 1.For the growth performance of piglets,the effect of GABA on growth performance was not significant(P>0.05).In the later stage of the experiment,the 20 mg/kg GABA group significantly increased the body weight and average daily gain of the test pigs on the 28 th day(P<0.05),but the other indexes of growth performance were not significant(P>0.05).In the whole phase of the experiment,the addition of 20 mg/kg GABA group could significantly reduce the weight-to-weight ratio of piglets(P<0.05),and significantly increase the average of piglets.The daily weight gain(P<0.05),the effect of GABA on other indicators of growth performance were not significant(P>0.05).Overall,GABA had the best effect on the whole phase of the experiment.2.For the apparent digestibility of nutrients,the supplementation of 20 mg/kg γ-aminobutyric acid significantly increased the apparent digestibility of Ca in piglets(P<0.05),while the apparent digestibility of the crude protein(CP),crude fat(EE),phosphorus(P)and dry matter(DM)was not significantly different from that in the control group(P>0.05).3.For the serum hormone index of piglets,the growth hormone(GH)level was significantly increased in each test group(P<0.01),and the highest growth hormone content was observed in the group of supplemented with 20mg/kg γ-aminobutyric acid;Compared with the control group,the level of leptin in the supplementation with 20mg/kg γ-aminobutyric acid group was significantly lower(P<0.01);Compared with the control group,the supplementation of γ-aminobutyric acid significantly altered the content of ghrelin(P<0.01),and the difference between the 20mg/kg γ-aminobutyric acid group and the 40 mg/kg γ-aminobutyric acid group was extremely significant(P<0.01).Compared with the control group,the content of cholecystokinin(CCK)was significantly decreased(P<0.05)when the piglets were supplemented with γ-aminobutyric acid.The supplementation of 20 mg/kg γ-aminobutyric acid group significantly increased the content of insulin-like growth factor 1(IGF-1)when compared with other treatment groups(P<0.05).There was no significant difference in the levels of corticotropin releasing hormone(CRH),adrenocorticotropic hormone(ACTH),cortisol(cortisol)and glucagon-like peptide 1(GLP-1)in each treatment group(P>0.05),but both were lower than the control group.4.For the immune performance of piglets,there were no significant differences in albumin(ALB),globulin(Globulin)and total protein(TP)between the experimental group and the control group(P>0.05),but each corresponding indicators of the treatment groups were higher than that in the control group.5.For the metabolic index of the serum of piglets,the serum glucose(Glucose)and urea nitrogen(BUN)content of each treatment group were not significantly different(P>0.05).6.for the number of E.coli,Lactobacillus and Bifidobacteria,there was no significant difference(P>0.05)between treatment groups,but the number of E.coli in each test group was lower than that in the control group.The number of lactobacilli and bifidobacteria was higher than that in the control group.In summary,the supplementation of 20 mg/kg γ-aminobutyric acid in diet of piglets can significantly improve the performance of piglets,regulate the secretion of hormones in the serum of piglets,and improve the immune function and intestinal microbes of piglets.