Effects of increased rapeseed meal addition on production performance, health, rumen fermentation, and microbial community in dairy goats

This experiment was designed to assess the influences of adding varying proportions of rapeseed meal (RSM) to the dietary concentrate on the production performance, milk quality, health status, rumen fermentation, and the characteristics of rumen and fecal flora of mid-lactation Xinong Saanen dairy goats. Thirty-six mid-lactation dairy goats, matched for age, parity, lactation stage, and body weight, were randomly divided into 3 concentrate feed), RSM10 (with 10% of RSM in the concentrate feed), and RSM15 (with 15% of RSM in the concentrate feed). The experiment lasted for 49 days, including a 7-d pre-feeding period and a 42-d trial period. During the trial period, milk yield and feed intake were recorded daily to assess production performance. Milk samples were collected biweekly to analyze milk composition. On day 42 of the experiment, blood, rumen fluid, and fecal samples were collected to evaluate health status and the structure of rumen and fecal microbiota. Results: With increasing addition of RSM, no significant changes were observed in milk production and milk components (P > 0.05). However, total antioxidant capacity and glutathione concentration in the blood significantly increased (P < 0.01), while malondialdehyde decreased (P < 0.01), and rumen NH3-N content declined (P < 0.05). Compared with the RSM5 group, the RSM10 group elevated the relative abundance of Bacteroidota and Rikenellaceae_RC9_gut_group in the rumen (P < 0.05) and reduced the relative abundance of Prevotellaceae_UCG-003 in the feces (P < 0.05). To sum up, this research indicates that substituting 10% of the soybean meal with RSM in the concentrate during the mid-lactation period has no adverse influence on the productive performance of dairy goats, but enhances the antioxidant capacity and improves the gastrointestinal microbiota.