Betaine improves growth performance by increasing digestive enzymes activities, and enhancing intestinal structure of weaned piglets

Abstract

This study investigated the effects of betaine on digestive enzymes and intestinal structures of weaned piglets. A total of 150 crossbred weaned piglets (Duroc × Landrace × Yorkshire), with an average initial body weight of 8.52 ± 0.26 kg and age of 39 day (weaned on day 25), were randomly divided into three dietary treatments, each of which was replicated five times with ten piglets per replicate/pen (five male piglets and five female piglets in each replicate/pen). The dietary treatments were basal diet supplemented with 0, 1250, 2500 mg/kg betaine, respectively. The experiment lasted 30 days. The results showed that supplementation of betaine in diet linearly increased average daily gain (ADG), decreased diarrhea rate, and improved feed conversion ratio (FCR). Betaine increased the apparent total tract digestibility of crude protein (CP) (linearly) and ether extract (EE) (linearly and quadratically) and the activities of amylase (linearly and quadratically), trypsin (linearly and quadratically), and lipase (linearly) in small intestine. The effect of betaine on digestive enzyme activities was more effective at 2500 mg/kg than that at 1250 mg/kg. In vitro enzymatic reaction studies found that betaine inclusion could boost the affinity of amylase and trypsin with their corresponding substrates, and counteract the inhibitory effect of hyperosmolarity induced by NaCl. Betaine also significantly increased villus height and the ratio of villus height to crypt depth of small intestine. Betaine increased the expression of tight junction proteins while decreased the plasma concentration of diamine oxidase (DAO). The effect of betaine on intestinal structure was more profound at 1250 mg/kg than that at 2500 mg/kg. Besides, betaine also increased the activity of glutathione peroxidase (GSH-Px) in the gut (linearly and quadratically). In conclusion, dietary supplementation of betaine enhanced intestinal structure and reduced diarrhea rate, increased digestive enzyme activities and promoted digestion of nutrients, and therefore, improved the growth performance of weaned piglets.