This study was conducted to establish dietary threonine (Thr) levels for Linwu ducks, aged 4 to 8 wk. Experimental diets formulated to contain 0.56, 0.61, 0.66, 0.71, 0.76, and 0.81% Thr fed to Linwu ducks. A total of 360 healthy Linwu female ducks with similar body weight (1183.89±3.83 g) were randomly divided into six groups, with five replicates in each group, and 12 ducks in each replicate. Samples were collected at 8 wk for the determination of growth performance, carcass traits, visceral organ indices, and serum biochemical parameters. As a result of this study, Thr level had no significant influence on the final weight, the daily gain, feed/gain ratio, and average daily intake (p>0.05). Similarly, there were no significant effects of dietary Thr on carcass traits and visceral organ indices (p>0.05). The pancreatic index was highest among all the treatments when the dietary Thr level was 0.66%. The different dietary Thr levels had no significant effect (p>0.05) on the concentration of total protein (TP), triglyceride (TG), total cholesterol (TC), glucose (GLU), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GSH-Px), and glutathione (GSH). However, the serum MDA concentration in the 0.66% treatment was lower (P=0.068) than in the other treatments. In conclusion, Thr at 0.66% concentration may have an antioxidant activity and exert positive effect on Linwu ducks.

The aim of this study was to investigate the effects of the forage type and chop length of ramie (Boehmeria nivea (L.) Gaud.) silage on rumen fermentation and ruminal microbiota in black goats. Sixteen Liuyang black goats (22.35 ± 2.16 kg) were fed with the roughage of corn silage or ramie silage at chop lengths of 1, 2, or 3 cm. The Chao 1 index and the observed number of microbial species differed significantly between the corn and ramie silage groups (p < 0.05); however, Firmicutes (relative proportion: 34.99–56.68%), Bacteroidetes (27.41–47.73%), and Proteobacteria (1.44–3.92%) were the predominant phyla in both groups. The relative abundance of Verrucomicrobia (0.32–0.82%) was lowest for the 2 and 3 cm chop lengths (p < 0.05) and was negatively correlated with rumen pH and propionic acid concentration (p < 0.05), but positively correlated with the ratio of acetic acid to propionic acid (p < 0.05). The ramie silage fermentation quality was highest for the 1 cm chop length, suggesting that moderate chopping produces optimal quality silage.