Effects of dietary supplementation of alfalfa polysaccharides on growth performance, small intestinal enzyme activities, morphology, and large intestinal selected microbiota of piglets
Zhang, C. Y.; Gan, L. P.; Du, M. Y.; Shang, Q. H.; Xie, Y. H.; Zhang, G. G.
Livestock Science 223: 47-52
It is suggested that the plant-derived polysaccharides have positive effect on improving the performance of livestock, but little information is available regarding their effects on piglets. This study aimed to assess the effects of alfalfa (Medicago saliva L.) polysaccharides (APS) on the growth performance and intestinal health of piglets. Two hundred 35-d-old piglets were randomly allotted to five groups fed basal diet supplemented with 0, 300, 500, 800, or 1200 mg APS /kg diet respectively for a 42-d experiment. Average daily gain (ADG), average daily feed intake (ADFI), feed efficiency (ADG/ADFI, G/F), small intestinal morphology, digestive enzymes activities, and selected large intestinal microbial populations were determined. Supplementation with APS to 35-to 77-d-old piglets quadratically (Q) (P < 0.05) or linearly (L) (P < 0.05) increased ADG and G/F values. Among all experimental groups, piglets that received 500 mg/kg diet of APS showed the highest numbers of Lactobacillus in cecum (P < 0.01), colon (P < 0.01), and rectum (P < 0.05). The numbers of Salmonella and Escherichia coli (E. coli) in all sections of the large intestine were reduced (P < 0.01) L and Q with increasing dietary APS concentration. Villus height presented L (P < 0.05 similar to 0.01) and/or Q (P < 0.05 similar to 0.01) enhancement in duodenum, jejunum and ileum with increasing supplementation of APS. Inclusion of APS L and Q decreased (P < 0.01) crypt depth and increased villus height/crypt depth ratio in jejunum and ileum. Piglets supplemented with increasing levels of APS presented higher protease and amylase activities in the small intestine (P < 0.05). Results showed that supplementation of APS up to 800 mg/kg diet enhanced gut morphological development and amylase and protease activities in the small intestine, promoted beneficial microbial populations in the large intestine, improved growth rate and feed efficiency in a dose-response manner. Combining all measured variables, the optimum dietary APS concentration appeared to be about 500 mg/kg diet.