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© 2015 Macmillan Publishers Limited. Ruminant livestock are important sources of human food and global greenhouse gas emissions. Feed degradation and methane formation by ruminants rely on metabolic interactions between rumen microbes and affect ruminant productivity. Rumen and camelid foregut microbial community composition was determined in 742 samples from 32 animal species and 35 countries, to estimate if this was influenced by diet, host species, or geography. Similar bacteria and archaea dominated in nearly all samples, while protozoal communities were more variable. The dominant bacteria are poorly characterised, but the methanogenic archaea are better known and highly conserved across the world. This universality and limited diversity could make it possible to mitigate methane emissions by developing strategies that target the few dominant methanogens. Differences in microbial community compositions were predominantly attributable to diet, with the host being less influential. There were few strong co-occurrence patterns between microbes, suggesting that major metabolic interactions are non-selective rather than specific., We thank Ron Ronimus, Paul Newton, and Christina Moon for reading and commenting on the manuscript. We thank all who provided assistance that allowed Global Rumen Census collaborators to supply samples and metadata (Supplemental Text 1). AgResearch was funded by the New Zealand Government as part of its support for the Global Research Alliance on Agricultural Greenhouse Gases. The following funding sources allowed Global Rumen Census collaborators to supply samples and metadata, listed with the primary contact(s) for each funding source: Agencia Nacional de Investigación e Innovación, Martín Fraga; Alberta Livestock and Meat Agency, Canada, Tim A. McAllister; Area de Ciencia y Técnica, Universidad Juan A Maza (Resolución Proy. N° 508/2012), Diego Javier Grilli; Canada British Columbia Ranching Task Force Funding Initiative, John Church; CNPq, Hilário Cuquetto Mantovani, Luiz Gustavo Ribeiro Pereira; FAPEMIG, Hilário Cuquetto Mantovani; FAPEMIG, PECUS RumenGases, Luiz Gustavo Ribeiro Pereira; Cooperative Research Program for Agriculture Science & Technology Development (project number PJ010906), Rural Development Administration, Republic of Korea, Sang-Suk Lee; Dutch Dairy Board & Product Board Animal Feed, André Bannink, Kasper Dieho, Jan Dijkstra; Ferdowsi University of Mashhad, Vahideh Heidarian Miri; Finnish Ministry of Agriculture and Forestry, Ilma Tapio; Instituto Nacional de Tecnología Agropecuaria, Argentina (Project PNBIO1431044), Silvio Cravero, María Cerón Cucchi; Irish Department of Agriculture, Fisheries and Food, Alexandre B. De Menezes; Meat & Livestock Australia; and Department of Agriculture, Fisheries & Forestry (Australian Government), Chris McSweeney; Ministerio de Agricultura y desarrollo sostenible (Colombia), Olga Lucía Mayorga; Montana Agricultural Experiment Station project (MONB00113), Carl Yeoman; Multistate project W-3177 Enhancing the competitiveness of US beef (MONB00195), Carl Yeoman; NSW Stud Merino Breeders’ Association, Alexandre Vieira Chaves; Queensland Enteric Methane Hub, Diane Ouwerkerk; RuminOmics, Jan Kopecny, Ilma Tapio; Rural and Environment Science and Analytical Services Division (RESAS) of the Scottish Government and the Technology Strategy Board, UK, R. John Wallace; Science Foundation Ireland (09/RFP/GEN2447), Sinead Waters; Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación, Mario A. Cobos-Peralta; Slovenian Research Agency (project number J1-6732 and P4-0097), Blaz Stres; Strategic Priority Research Program, Climate Change: Carbon Budget and Relevant Issues (Grant No.XDA05020700), ZhiLiang Tan; The European Research Commission Starting Grant Fellowship (336355—MicroDE), Phil B. Pope; The Independent Danish Research Council (project number 4002-00036), Torsten Nygaard Kristensen; and The Independent Danish Research Council (Technology and Production, project number 11-105913), Jan Lassen. These funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

The aim of this study was to determine the nutritional requirements of energy and protein for maintenance and weight gain of crossbred cattle, as well as their efficiencies. Fifty 3/4 Zebu × 1/4 Holstein crossbred bulls with initial weights of 214±4kg and aged 11±0.2 months on average were used in this experiment. Four animals were used in the reference group; ten bulls were fed at the maintenance level; and the remaining 36 bulls were fed ad libitum and distributed in a completely randomized design in a 3×3 factorial arrangement, which had three feedlot periods (56, 112 or 168 days) and three calcium and phosphorus levels (low, medium and normal) in the diet. Four of the maintenance animals had their heat production measured by respirometry at the Laboratory of Metabolism and Calorimetry of UFMG. After slaughter, composite samples, referred to as carcass and noncarcass samples were obtained from each animal. The net energy requirements for maintenance (NEm) and metabolizable energy for maintenance (MEm) were 68.9 and 90.1 kcal/EBW0.75/day, respectively. The efficiency (km) was 76.41%. The NEm requirement determined in the respirometry chamber was 85.5 kcal/kg0.75. The following equations were obtained for net energy for gain (NEg) and net protein for gain (NPg): NEg (Mcal/day) = 0.0505±0.000986 × EBW0.75× EBWG1.095 and NPg (g/day) = 162.79±18.2546 × EBWG - 1.30±5.3010 × RE. The efficiencies of fat and protein deposition were 70.04 and 15.12%, respectively. In conclusion, the requirements of NEm for growing and finishing non-castrated 3/4 Zebu × 1/4 Holstein crossbred cattle are 68.9 kcal/EBW0.75/day. Requirements of NEg and NPg can be obtained by the following equations: NEg(Mcal/day) = 0.05050.000986 × EBW0.75 × EBWG1.095and NPg (g/day) = 162.79±18.2546 × EBWG - 1.30±5.3010× RE. Objetivou-se determinar as exigências nutricionais de energia e proteína para mantença e ganho de peso de bovinos cruzados, bem como suas eficiências. Foram utilizados 50 bovinos cruzados 3/4 Zebu × 1/4 Holandês, não castrados, com peso inicial de 214±4kg e idade média de 11±0,2 meses. Quatro animais foram usados para referência, dez para o grupo mantença e os 36 animais alimentados à vontade foram distribuídos em delineamento inteiramente ao acaso em esquema fatorial 3×3, sendo três períodos de confinamento (56, 112 ou 168 dias) e três níveis de cálcio e fósforo (baixo, médio e normal) na dieta. Quatro dos animais mantença foram encaminhados ao laboratório de metabolismo e calorimetria da UFMG para medição da produção de calor através da respirometria. Após os abates, foram obtidas duas amostras compostas para cada animal, denominadas carcaça e não carcaça. As exigências de energia líquida para mantença (ELm) e energia metabolizável para mantença (EMm) foram, respectivamente, de 68,9 e 90,1kcal/PCVZ0,75/dia. A eficiência (km) foi de 76,41%. A exigência de ELm obtida na câmara respirométrica foi de 85,5kcal/kg0,75. As equações obtidas para energia líquida de ganho (ELg) e proteína líquida de ganho (PLg) foram: ELg(Mcal/dia) = 0,0505±0,000986 × PCVZ 0,75 × GPCVZ 1,095e PLg (g/dia) = 162,79±18,2546 × GPCVZ - 1,30±5,3010 × ER. As eficiências para deposição de gordura e de proteína foram de 70,04 e 15,12%, respectivamente. Conclui-se que as exigências de ELm para bovinos cruzados 3/4 Zebu × 1/4 Holandês não castrados em crescimento e terminação são de 68,9kcal/PCVZ0,75/dia; e que as exigências de ELg e PLg podem ser obtidas pelas respectivas equações: ELg(Mcal/dia) = 0,0505±0,000986 × PCVZ 0,75 × GPCVZ 1,095e PLg (g/dia) = 162,79±18,2546 × GPCVZ - 1,30±5,3010 × ER.

Productive performance of crossbreds Nellore beef heifers, in the growing stage receiving different supplement levels for three months grazing Brachiaria decumbens pasture were evaluated. The area was divided in five paddocks of 2.5 ha, with dry matter availability and potentially of dry matter digestible of 3.85 and 2.12 t/ha, respectively. Forty beef heifers of 191 ± 3.99 kg initial weight and 8.5 ± 0.15 months of age were assigned in a completely randomized experimental design with five treatments, and four supplementation levels. Mineral mixture (MM) (60 g/day) and multiple supplements, formulated to supply different supplementation levels in the amounts of 0.5, 1.0, 1.5 and 2.0 kg/animal more MM (60 g/day) were evaluated. The supplement had 300 g of crude protein/kg. Animals not responded significantly (P > 0.05) to the use of multiples supplements to final body weight. However, the heifers than received supplement won more weight (P £ 0.01) (372 g vs. 92g of average daily gain), in addition to highers (P £ 0.01) serum N-urea levels (20.14 vs. 12.09 mg/dL), when compared with heifers fed diets supplied only with mineral mixture. In conclusion, increasing the amount of protein supplement during the dry season, increased of performance of beef heifers. However, despite increase productive performance and intake of energy during dry season, additional higher levels of supplementation resulted in lower increment in growth.

The objective of this study was to estimate requirements of energy, protein and macrominerals of young Nellore/Holstein crossbreds bulls supplemented on pastures of Brachiaria decumbens Stapf. Thirty-five young bulls, at 8.53±0.18 months of age and with initial body weight of 230.6±6.1 kg were used. Ten animals were slaughtered as reference, in different weight range, and the other animals were slaughtered at the end of the experimental period. For estimate of net energy requirements for weight, a regression equation between log of retained energy (RE) and log of empty body weight gain (EBWG) was constructed. Net requirements of Ca, P, Mg, Na and K were determined by the equation Y' = a.b.Xb-1, in which a and b represent the intercept and the coefficient of equation of prediction of macrominerals in body content, respectively. Requirements of metabolizable energy for maintenance (MEm) were obtained from retained energy in function of metabolizable energy intake (MEI). The requirements of MEm of Nellore/Holstein crossbreds young bulls on pasture was 125 kcal/EBW0.75/day. The efficiency of ME utilization for maintenance (km) of grazing Nellore/Holstein crossbred young bulls was 0.58 and 0.24 for gain. The total metabolizable protein requirements for an animal with 400 kg and with average daily gain of 1.0 kg, were 638.36 g/day. The dietetic requirements of Ca and P for an animal with 400 kg BW were 0.49 and 0.21% of DM, respectively. Daily metabolizable energy requirement for maintenance of grazing Nellore/Holstein crossbred young bulls was 11.6% greater than the values found for cattle in feedlot in Brazil (112 kcal/kg EBW0.75).