Effects ofβ-alanine on intestinal development and immune performance of weaned piglets

Beta-alanine is an important amino acid involved in several metabolic reactions in the body.The study aimed to investigate the effect ofβ-alanine supplementation on intestinal development and the immune performance of weaned piglets.Thirty-two 21-day-old healthy weaned piglets(half female and half male;Duroc×Landrace×Yorkshire)with an initial body weight of 8.11±0.21 kg were randomly divided into 4 groups with 8 replicates of 1 pig each.The control group was fed a basal diet and the three experimental treatment groups were fed diets supplemented with 300,600 and 1,200 mg/kgβ-alanine,respectively.The trial lasted 28 days and the diets fed were divided into 2 phases:the late lactation period(day 1 to 14)and the nursery period(day 15 to 28),during which the weaned piglets had free access to food and water.The regulatory effects ofβ-alanine were further investigated in vitro using organoids obtained from the jejunum of piglets.In vivo,the addition ofβ-alanine to the diet had no significant effect on the growth performance of weaned piglets(P>0.05),but significantly reduced serum levels of immunoglobulin G(IgG)(P<0.01),immunoglobulin M(IgM)(P=0.005),and complement 3(C3)(P=0.017).The serum interleukin-6(IL-6)levels(P<0.01)were significantly reduced in the 1,200 mg/kg treatment group.The addition ofβ-alanine increased ileal villus height,with the most significant effect at a concentration of 300 mg/kg(P=0.041).The addition of 600 mg/kgβ-alanine significantly up-regulated the expression of superoxide dismutase(SOD)activity(P=0.020)and the zonula occludens-1(ZO-1)gene(P=0.049)in the jejunum.Diets supplemented with 300 mg/kgβ-alanine significantly increased the number of Ki67 positive cells in the jejunal crypts(P<0.01).In vitro,β-alanine increased the organoid budding rates(P=0.001)and the budding height of the crypt significantly(P=0.004).In conclusion,β-alanine can improve intestinal morphology and barrier function,reduce inflammatory responses and alleviate the adverse effects of weaning stress on piglet intestinal health.