Dietary Polysaccharide-Rich Extract from Noni (Morinda citrifolia L.) Fruit Modified Ruminal Fermentation, Ruminal Bacterial Community and Nutrient Digestion in Cashmere Goats

SIMPLE SUMMARY: Due to the seasonal imbalance and limited nutrients in pastures available for grazing in China, cashmere goats are often raised in a confined yard-feeding system, which may lead to metabolic disease from a lack of green pastures. The rumen is an important organ for nutrient metabolism in ruminants. Noni (Morinda citrifolia L.) could promote in vitro ruminal fermentation in lactating dairy goats. In addition, Noni fruit polysaccharides could alleviate inflammatory bowel disease by regulating the intestinal microbial composition in mice. Therefore, noni fruit polysaccharides may help ruminants to metabolize nutrients. The aim of this experiment was to characterize the effects of polysaccharide-rich noni fruit extract (NFP) on ruminal fermentation, ruminal microbiota and nutrient digestion in cashmere goats combining in vitro and in vivo techniques. The results showed that NFP depressed protozoa, improved N utilization and enhanced ruminal fermentation in vitro, which was better when the dosage was 0.40%. This dosage yielded similar results in vivo and promoted nutrient digestibility. In addition, the high proportion of Firmicutes/Bacteroides might be compensation for the decrease in protozoa, and the increase in volatile fatty acid concentration might be associated with the greater abundance of Ruminococcus_1. The Rikenellaceae_RC9_gut_group might have a negative effect on ruminal N utilization. ABSTRACT: In two consecutive studies, we evaluated the effects of polysaccharide-rich noni (Morinda citrifolia L.) fruit extract (NFP) on ruminal fermentation, ruminal microbes and nutrient digestion in cashmere goats. In Exp. 1, the effects of a diet containing NFP of 0, 0.1%, 0.2%, 0.4% and 0.55% on in vitro ruminal fermentation at 3, 6, 9, 12 and 24 h were determined, whereas in Exp. 2, fourteen cashmere goats (46.65 ± 3.36 kg of BW ± SD) were randomly assigned to two treatments: the basal diet with or without (CON) supplementation of NFP at 4 g per kg DM (0.4%). The in vitro results showed that NFP linearly increased concentrations of volatile fatty acids (VFA), quadratically decreased ammonia-N concentration, and changed pH, protozoa number, gas production and the microbial protein (MCP) concentration, and was more effective at 0.4% addition, which yielded similar results in ruminal fermentation in Exp. 2. In addition, NFP increased the apparent digestibility of dry matter and crude protein and the abundance of Firmicutes, and reduced the abundance of Bacteroides and Actinobacteria. Ruminococcus_1 was positively associated with VFA concentration. The Rikenellaceae_RC9_gut_group was positively correlated with protozoa and negatively correlated with MCP concentration. Thus, NFP has potential as a ruminal fermentation enhancer for cashmere goats.