Nutrient digestion, rumen fermentation and performance as ramie (Boehmeria nivea) is increased in the diets of goats

The objective of this study was to investigate the variations in nutrient digestibility, rumen fermentation, serum biochemical parameters, and performance resulting from an increase in the proportion of ramie (Boduneria nivea) substitution for alfalfa in the diets of goats. In a completely randomized block design, thirty-two Liuyang black goats were divided into two blocks according to body weight (BW) (light, BW: 16.7 +/- 1.72 kg; and heavy, BW: 26.6 +/- 2.95 kg). Then, the sixteen goats in each block were further randomly divided into four subgroups that randomly accepted four treatments, i.e., alfalfa was replaced by ramie at 0%, 35%, 70% and 100%. The results showed that the apparent digestibility of gross energy (GE) (linear, p < 0.05), crude protein (CP) (linear, p < 0.01), neutral detergent fiber (NDF) (linear, p < 0.01), acid detergent fiber (ADF) (linear, p < 0.001), ash (linear, p < 0.001) and Ca (linear, p < 0.001) decreased with the increase in the proportion of ramie, while phosphorous (P) digestibility increased (linear, p < 0.001) with the increment in the proportion of dietary ramie. The concentration of total volatile fatty acid (TVFA) and the proportion of individual volatile fatty acids were unaffected (p > 0.05) by the inclusion of ramie. The concentration of ammonia nitrogen (NH3-N) in the rumen fluid decreased (linear, p < 0.01) with increasing dietary ramie level. The increasing proportion of dietary ramie caused a decrease (linear, p < 0.001; quadratic, p < 0.001) in the body weight gain of the goats. The serum concentration of triglyceride (TG) (quadratic, p < 0.05), high-density lipoprotein cholesterol (HDLC) (quadratic, p < 0.05), albumin (ALB) (linear, p < 0.05; quadratic, p < 0.05), calcium (Ca) (quadratic, p < 0.05) and alkaline phosphatase (ALP) increased by increasing the percentage of ramie in the diet of goats. The current results indicate that a higher proportion of dietary alfalfa replaced by ramie decreases nutrient digestion, body weight gain and calcium level. The proper proportion of ramie used in the diets of growing goats is no more than 126 g/kg dry matter (DM).