Effects of chito-oligosaccharide supplementation with low or medium molecular weight and high degree of deacetylation on growth performance, nutrient digestibility and small intestinal morphology in weaned pigs

Chito-oligosaccharide (COS) supplementation in nursery diets has been found to improve piglets' performance. However, little is known on which COS characteristics are responsible for its effect. The present study was designed to further study how COS characteristics: molecular weight (MW) and degree of deacetylation (DD); affect the growth performance, nutrient digestibility, and small intestinal modifications in weaning pigs. For this purpose, 48 weanling pigs were divided into 4 groups (12 animals per group) and received either a basal diet or a basal diet supplemented with 150 mg/kg of COS which differed in MW and DD: 8 kDa and similar to 90% DD (8 kDa similar to 90%), 65 kDa and similar to 80% DD (65 kDa similar to 80%), and 65 kDa and similar to 90% DD (65 kDa similar to 90%). The experiment lasted 56 days. There were treatment effects on pigs' body weight gain (BWG), average daily gain (ADG), average daily feed intake (ADFI), blood urea nitrogen (BUN), digestibility of crude protein, fat and calcium, small intestinal morphology and crypt cell proliferation (P < .05, respectively). Throughout the study, pigs supplemented with 8 kDa similar to 90% COS showed significantly enhanced BWG, ADG, and ADFI when compared to those supplemented with 65 kDa similar to 80% COS (P < .05, respectively). The enhanced growth performances in pigs supplemented with 8 kDa similar to 90% COS was supported by an increase in ADFI (P < .05), and improved ileal digestibility of crude protein and crude fat (P < .01, respectively). Pigs supplemented with 8 kDa similar to 90% COS also had increased absorption capacity as indicated by elongated villus height and increased villus height to crypt depth ratio of the small intestinal segments (P < .05, respectively), and more active cell division as indicated by increased Ki-67 marker at jejunal crypt cells (P < .05) on day 28 and 56 of the experiment. These data suggest that 8 kDa similar to 90% might be the most effective form of COS to improve feed intake, and promote nutrient digestibility and absorption when supplemented at 150 mg/kg in the diet.