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Methane emissions from ruminants enhance global warming and lead to a loss of feed energy. The emissions are low when fed brassica crops, but the factors contributing to low emissions are unknown. A meta‐analysis was conducted with individual animal data collected from seven experiments. In these experiments, methane emissions were measured using respiration chambers. Animal characteristics, feed chemical composition and rumen fermentation parameters were included for the analysis using multiple regression models. Feed intake level, animal live weight and age were animal factors that were weakly and negatively related to methane yield (g/dry matter intake). The duration in which sheep were fed brassica crops was a significant contributor in the model, suggesting that the effect on emissions diminishes with time. Among a range of feed chemical composition characters, acid detergent fibre and hot‐water‐soluble carbohydrate contributed significantly to the model, suggesting that both structural and soluble carbohydrates affect methane formation in the rumen. There was no significant correlation between the concentration of sulphate in brassicas and emissions, but nitrate was moderately and negatively correlated with methane yield (r = −.53). Short‐chain fatty acid profiles in the rumen of animals fed brassicas were different from those fed pasture, but these parameters only moderately correlated to methane emissions (r =.42). Feeding forage rape resulted in low rumen pH. The pH before morning feeding was strongly correlated to methane yield (r =.90). Rumen pH, together with microbial communities mediated by pH, might lead to low emissions. Bacteria known to produce hydrogen were relatively less abundant in the rumen contents of brassica‐fed animals than pasture‐fed animals. In conclusion, animal and feed factors, rumen fermentation and microbial communities all affect methane emissions to some extent. The interactions of these factors with each other thus contribute to methane emissions from brassica‐fed sheep. [ABSTRACT FROM AUTHOR]

This study investigated the effect of replacing corn grain, soybean meal and wheat bran with tropical agricultural by‐products, such as palm kernel cake (PKC), cassava residue and dried distiller's grain with solubles (DDGS), on the dry matter intake (DMI), growth performance, apparent nutrient digestibility, ruminal short‐chain fatty acids (SCFA) and ruminal microbial communities of water buffaloes. Thirty healthy 15‐month‐old crossbred water buffaloes with a similar initial body weight of 353.1 ± 23.7 kg were randomly allocated into three dietary experimental groups, and they were fed with same forage but three different concentrates for 50 days fattening. The dietary treatments were as following: typical concentrate (TC, 65% corn + 15% wheat bran + 15% soybean meal), partial replacement concentrate Ⅰ (PRC I, 50% corn + 22.5% corn gluten + 22.5% PKC) and partial replacement concentrate Ⅱ (PRC II, 50% corn + 22.5% cassava residue + 22.5% DDGS). The results showed that the average daily gain of the PRC II group was the highest, and the DMI, acid detergent fibre digestibility and neutral detergent fibre digestibility value of the three groups were different and in the following order: PRC II group > TC group > PRC I group. The crude protein digestibility of PRC II was higher than that of the TC and PRC I groups (p <.05). The ruminal concentrations of total SCFA, acetate, propionate and butyrate of TC group were higher than the other two groups (p <.05). The PRC I group had the highest Bacteroidetes‐to‐Firmicutes ratio (B/F) and relative abundance of the genus Prevotella, while the PRC II group had the lowest B/F and relative abundance of Prevotella. In conclusion, using PKC and corn gluten to completely replace common feed ingredients in the buffalo concentrate ration decreased, while using cassava residue and DDGS increased animal growth performance, mainly due to the different combination influenced nutrient digestibility and ruminal microbial community composition was shifted. [ABSTRACT FROM AUTHOR]

Simple Summary: Ruminant production relies on nutrients obtained from feed fermentation in the rumen. In grazing ruminant production systems, fresh forage is the major or sole source of feed. Feeding frequency and feeding level are two important factors affecting rumen fermentation. This study investigated how these factors affect the fermentation of fresh forage in the rumen for in-depth evaluation of the nutritional value of two types of forages and for better understanding of their digestion by ruminants. To achieve the objectives of the study, fresh chicory or perennial ryegrass was fed to sheep hourly or twice-daily at low or high feeding levels. The results indicated that rumen fermentation was affected by forage species, feeding frequency, feeding level and their interactions and the differences in rumen fermentation were more apparent when feeding was performed hourly rather than twice-daily. This study highlighted the importance of feeding frequency on manipulating sheep ruminal metabolism when fed fresh forage. Feeding frequency and feeding level are two important factors affecting rumen fermentation characteristics, but few studies on these have been conducted on fresh forage. Eight rumen-fistulated sheep were fed either fresh chicory or perennial ryegrass hourly in the first period (d 14 to 21) of the experiment and twice-daily in the second period (d 22 to 27) at 1.3 or 2.2 times the requirement of metabolizable energy for maintenance. When fed hourly, but not twice-daily, rumen fluid pH value was affected by forage species and feeding level. The total concentrations of short-chain fatty acid (SCFA) were similar at both feeding levels when fed chicory hourly, but they were greater at the higher feeding level in comparison with the lower feeding level when fed perennial ryegrass. However, forage species and feeding level did not affect rumen fluid total SCFA concentration when sheep were fed twice-daily. Therefore, rumen fermentation characteristics were affected by forage species, feeding frequency, feeding level and their interactions and the differences in fermentation characteristics were more apparent when feeding was performed hourly rather than twice-daily. This study highlighted the importance of feeding frequency on manipulating sheep ruminal metabolism when fed fresh forage. [ABSTRACT FROM AUTHOR]