Duthie C-A, Haskell M, Hyslop J J, Waterhouse A, Wallace R J, Roehe R, Rooke J A
1Future Farming Systems Group,Beef and Sheep Research Centre,SRUC,Kings Buildings,West Mains Road,Edinburgh EH9 3JG,UK.
2Animal Behaviour and Welfare,Animal and Veterinary Sciences Group,SRUC,Kings Buildings,West Mains Road,Edinburgh EH9 3JG,UK.
Animal. 2017 Oct;11(10):1762-1771. doi: 10.1017/S1751731117000301. Epub 2017 Feb 22.
This study was undertaken to further develop our understanding of the links between breed, diet and the rumen microbial community and determine their effect on production characteristics and methane (CH4) emissions from beef cattle. The experiment was of a 2×2 factorial design, comprising two breeds (crossbred Charolais (CHX); purebred Luing (LU)) and two diets (concentrate-straw or silage-based). In total, 80 steers were used and balanced for sire within each breed, farm of origin and BW across diets. The diets (fed as total mixed rations) consisted of (g/kg dry matter (DM)) forage to concentrate ratios of either 500 : 500 (Mixed) or 79 : 921 (Concentrate). Steers were adapted to the diets over a 4-week period and performance and feed efficiency were then measured over a 56-day test period. Directly after the 56-day test, CH4 and carbon dioxide (CO2) emissions were measured (six steers/week) over a 13-week period. Compared with LU steers, CHX steers had greater average daily gain (ADG; P<0.05) and significantly (P<0.001) lower residual feed intake. Crossbred Charolais steers had superior conformation and fatness scores (P<0.001) than LU steers. Although steers consumed, on a DM basis, more Concentrate than Mixed diet (P<0.01), there were no differences between diets in either ADG or feed efficiency during the 56-day test. At slaughter, however, Concentrate-fed steers were heavier (P<0.05) and had greater carcass weights than Mixed-fed steers (P<0.001). Breed of steer did not influence CH4 production, but it was substantially lower when the Concentrate rather than Mixed diet was fed (P<0.001). Rumen fluid from Concentrate-fed steers contained greater proportions of propionic acid (P<0.001) and lower proportions of acetic acid (P<0.001), fewer archaea (P<0.01) and protozoa (P=0.09), but more Clostridium Cluster XIVa (P<0.01) and Bacteroides plus Prevotella (P<0.001) than Mixed-fed steers. When the CH4 to CO2 molar ratio was considered as a proxy method for CH4 production (g/kg DM intake), only weak relationships were found within diets. In conclusion, although feeding Concentrate and Mixed diets produced substantial differences in CH4 emissions and rumen characteristics, differences in performance were influenced more markedly by breed.
本研究旨在进一步加深我们对品种、日粮与瘤胃微生物群落之间联系的理解，并确定它们对肉牛生产性能特征和甲烷（CH4）排放的影响。试验采用2×2析因设计，包括两个品种（夏洛莱杂交牛（CHX）；纯种卢因牛（LU））和两种日粮（精料-秸秆型或青贮型）。总共使用了80头阉牛，并在每个品种内按父系、原产地农场和不同日粮的体重进行了平衡。日粮（以全混合日粮形式饲喂）的干物质（DM）中，粗饲料与精料的比例分别为500:500（混合）或79:921（精料）。阉牛在4周内适应日粮，然后在56天的试验期内测定生产性能和饲料效率。在56天试验结束后，立即在13周内测定CH4和二氧化碳（CO2）排放（每周6头阉牛）。与LU阉牛相比，CHX阉牛的平均日增重（ADG）更高（P<0.05），残余采食量显著更低（P<0.001）。夏洛莱杂交阉牛的体型和肥度评分优于LU阉牛（P<0.001）。虽然阉牛在干物质基础上采食的精料比混合日粮多（P<0.01），但在56天试验期内，两种日粮在ADG或饲料效率方面没有差异。然而，在屠宰时，精料饲喂的阉牛体重更重（P<0.05），胴体重量也比混合日粮饲喂的阉牛更大（P<0.001）。阉牛品种不影响CH4产量，但饲喂精料日粮时CH4产量显著低于混合日粮（P<0.001）。精料饲喂阉牛的瘤胃液中丙酸比例更高（P<0.001），乙酸比例更低（P<0.001），古菌（P<0.01）和原生动物数量更少（P=0.09），但梭菌属 XIVa 群（P<0.01）以及拟杆菌属和普雷沃菌属数量更多（P<0.001），高于混合日粮饲喂的阉牛。当将CH4与CO2的摩尔比作为CH4产量（g/kg DM采食量）的替代方法时，在不同日粮中仅发现微弱的关系。总之，虽然饲喂精料日粮和混合日粮在CH4排放和瘤胃特征方面产生了显著差异，但生产性能的差异受品种影响更为明显。
