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The purpose of this study is to reveal the effects of different particle sizes of rice straw on the rumen protozoa count, nutrient disappearance rate, rumen fermentation, and microbial community in a rumen simulation technique (RUSITEC) system. In this experiment, a single-factor random trial design was adopted. According to the different particle sizes of rice straw, there were three treatments with three replies in each treatment. Three kinds of goat total mixed ration (TMR), with the same nutrients were used to carry out a 10 days in vitro fermentation experiment using the rumen simulation system developed by Hunan Agricultural University, including 6 days the pretrial period and 4 days formal period. This study found that the organic matter disappearance rate, concentrations of total volatile fatty acids (VFAs), acetate, propionate, and iso-butyrate were greatest in the 4 mm group (p < 0.05). There were no significant differences in the alpha diversity, among the three groups (p > 0.05). The relative abundance of Treponema and Ruminococcus of the 2 mm group increased; the relative abundance of Butyrivibrio and Prevotella in samples increased in the 4 mm group. In addition, the results of correlation analysis showed that Prevotella and Ruminococcus was positively correlated with butyrate, ammonia-N, dOM and d ADF (p < 0.05) and negatively correlated with valerate (p < 0.05); Oscillospira was positively correlated with valerate (p < 0.01) and negatively correlated with propionate, butyrate, ammonia-N, dOM and dADF (p < 0.05). The present results imply that compared to the other groups, rice straw particle size of 4 mm may improve the disappearance rate of nutrients and promote the production of volatile fatty acids by regulating ruminal microorganisms.

In order to study the regulation of Fenugreek seed extract (FSE) on the immunity of broilers, and explore the appropriate amount of FSE in broilers' production, 1-day-old yellow feather broilers with a total of 420 birds were randomly allocated into seven treatments. Each treatment had six replicates, with 10 birds per replicate. The two control groups were the basic fodder group fed with basal diet and the bacitracin zinc group added 30 mg/kg bacitracin zinc to the basal diet. Experimental groups included five levels of FSE (50, 100, 200, 400, and 800 mg/kg FSE to the basal diet, respectively). The pre-test period was 7 days and the formal test lasted for 56 days. The results showed that the average daily gain (ADG) of 50 and 800 mg/kg FSE groups was significantly increased (P < 0.01), and the feed to gain ratio (F/G) of FSE groups was significantly decreased (P < 0.01) compared with the basic fodder and the bacitracin zinc groups. Compared with the basic fodder group, the serum total cholesterol (TC) content in the FSE groups was significantly decreased (P < 0.05), the serum low density lipoprotein cholesterol (LDL-C) content of 50, 100, and 800 mg/kg FSE groups was significantly lower than that of the basic fodder group (P < 0.05). Compared with the basic fodder and bacitracin zinc groups, the serum immunoglobulins (IgG, IgM, IgA) content of 100 and 200 mg/kg FSE groups were significantly increased (P < 0.05). Compared with the bacitracin zinc group, the serum interleukins (IL-1, IL-10) content of 400 mg/kg FSE group were significantly increased (P ≤ 0.05), and the serum interferon-γ (IFN-γ) content of 100 and 200 mg/kg FSE groups was significantly increased (P < 0.05). Compared with the basic fodder group, the lower doses (0–400 mg/kg) of FSE had no significant effect on the mRNA expression of toll-like receptors 4/ myeloid differentiation factor 88/ nuclear factor-κB (TLR4/MyD88/NF-κB) signaling pathways (P > 0.05). The 800 mg/kg FSE treatment group significantly increased the expression levels of nuclear factor-κB (NF-κB) mRNA in the spleen of broilers (P < 0.05). The zinc bacitracin group significantly increased the expression levels of myeloid differentiation factor 88 (MyD88) and nuclear factor-κB (NF-κB) mRNA (P ≤ 0.05). The results showed that FSE could promote the secretion of immunoglobulins, regulate the body's cytokines, and have a positive effect on immunity in broilers. Furthermore, the recommended supplement of FSE is 100 mg/kg in the broiler diet.