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Methane (CH4) is a greenhouse gas (GHG) produced and released by eructation to the atmosphere in large volumes by ruminants. Enteric CH4 contributes significantly to global GHG emissions arising from animal agriculture. It has been contended that tropical grasses produce higher emissions of enteric CH4 than temperate grasses, when they are fed to ruminants. A number of experiments have been performed in respiration chambers and head-boxes to assess the enteric CH4 mitigation potential of foliage and pods of tropical plants, as well as nitrates (NO3−) and vegetable oils in practical rations for cattle. On the basis of individual determinations of enteric CH4 carried out in respiration chambers, the average CH4 yield for cattle fed low-quality tropical grasses (>70% ration DM) was 17.0 g CH4/kg DM intake. Results showed that when foliage and ground pods of tropical trees and shrubs were incorporated in cattle rations, methane yield (g CH4/kg DM intake) was decreased by 10% to 25%, depending on plant species and level of intake of the ration. Incorporation of nitrates and vegetable oils in the ration decreased enteric CH4 yield by ∼6% to ∼20%, respectively. Condensed tannins, saponins and starch contained in foliages, pods and seeds of tropical trees and shrubs, as well as nitrates and vegetable oils, can be fed to cattle to mitigate enteric CH4 emissions under smallholder conditions. Strategies for enteric CH4 mitigation in cattle grazing low-quality tropical forages can effectively increase productivity while decreasing enteric CH4 emissions in absolute terms and per unit of product (e.g. meat, milk), thus reducing the contribution of ruminants to GHG emissions and therefore to climate change. [ABSTRACT FROM AUTHOR]

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The objectives were to assess the following: (1) the relationship between sward height and chemical composition of four pasture types in association with grazing behaviour and body condition score (BCS) of dairy cows, and (2) the possibility of developing predictive equations of the nutrient intake and grazing behaviour within a continued grazing system. Pasture type had a significant (p < 0.01) effect on nutrient supply from January to June for all pastures investigated. Ryegrass–white clover pasture (RW) had the highest metabolizable protein and metabolizable energy, followed by kikuyu pasture (KP), which was significantly (p < 0.001) higher than native pastures 1 and 2 (NP1 and NP2). The highest values for effective grazing time, bite rate and BCS were found when dairy cows grazed RW followed by KP, NP2 and NP1. The results suggested that pasture type and sward height influenced grazing behaviour and BCS of dairy cows during the dry season. In the same vein, RW showed higher effective grazing time, bite rate, nutrient intake and BCS than the other three pastures suggesting that RW pastures that appear to be more expensive than native pastures could result in superior cow performance. [ABSTRACT FROM PUBLISHER]

Four accessions of Cratylia argentea CIAT 18516, 18666, 18668 and 18676, were evaluated during an uninterrupted growth period of 12 months, to assess forage yield of leaves (LF), edible (ES) and non edible (NS) stem and nutritive quality of LF and ES, in the State of Veracruz, México. Forage yield of the plant components was similar between accessions: 2580±212, 33±5 and 2444±233 kg DM/ha, for LF, ES and NS, respectively. The accessions were similar in crude protein (19.10%), neutral detergent fiber (61.10%), acid detergent fiber (42.20%), and lignin (14.20%). LF had more crude protein than ES, but was lower with respect to NDF, ADF, and higher in LIG. For in situ DM disappearance, accessions differed in the highly soluble component (a) of the dry matter proportion; but all had a similar fractional rate of degradation (c) and a slow degradable dry matter (b). The in vitro gas production of the leaf component was the same for all accessions. It was concluded that in the present evaluation the accessions were similar between them. [ABSTRACT FROM AUTHOR]

Methane (CH 4 ) is a greenhouse gas generated during the feed fermentation processes in the rumen. However, numerous studies have been conducted to determine the capacity of plant secondary metabolites to enhance ruminal fermentation and decrease CH 4 production, especially those plants rich in tannins. This review conducted a descriptive analysis and meta-analysis of the use of tannin-rich plants in tropical regions to mitigate CH 4 production from livestock. The aim of this study was to analyse the effect of tannins supplementation in tropical plants on CH 4 production in ruminants using a meta-analytic approach and the effect on microbial population. Sources of heterogeneity were explored using a meta-regression analysis. Final database was integrated by a total of 14 trials. The 'meta' package in R statistical software was used to conduct the meta-analyses. The covariates defined a priori in the current meta-regression were inclusion level, species (sheep, beef cattle, dairy cattle, and cross-bred heifers) and plant. Results showed that supplementation with tropical plants with tannin contents have the greatest effects on CH 4 mitigation . A negative relationship was observed between the level of inclusion and CH 4 emission (-0.09), which means that the effect of CH 4 mitigation is increasing as the level of tannin inclusion is higher. Therefore, less CH 4 production will be obtained when supplementing tropical plants in the diet with a high dose of tannins., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 The Authors. Published by Elsevier Ltd.)