RESUMO
We tested the hypothesis that improving sward structure through adjustments in forage allowance results in greater forage intake and live weight (LW) gains by beef cattle and lower CH4 emissions per unit LW gain and unit area in a native grassland ecosystem of the Pampa biome. The experiment was carried out during 2012 and 2013 in southern Brazil. The experimental design was a randomized complete block with two replicates. Treatments consisted of five contrasting forage allowances of a native grassland managed under continuous stocking: 4, 8, 8-12, 12, and 16 kg of dry matter (DM) 100 kg LW-1 day-1 (or % LW). The 8-12% LW treatment had a variable forage allowance of 8% LW in spring and 12% LW in summer, autumn, and winter. Forage allowance was controlled by changes in stocking rate (kg LW ha-1). Average daily gain (kg LW day-1) was high for forage allowances of 12 and 16% LW but decreased at 8%, reaching the lowest value at 4% LW treatment (p < 0.001). Live weight gain ha-1 year-1 was the greatest at forage allowance of 8-12% LW (p < 0.001). Forage DM intake peaked at a forage allowance of 12% LW (p = 0.005). Individual CH4 emissions remained constant around 150 g day-1 for the two highest forage allowances and decreased to 118 and 107 g day-1 under forage allowances of 8 and 4% LW, respectively (p = 0.002). Emissions per unit LW gain and unit area were driven by animal productivity changes and decreased with increasing forage allowance (p = 0.001 and p = 0.040, respectively). We propose that the combination of 8% LW forage allowance during spring and 12% LW during the rest of the year should be targeted to best balance animal production and environmental impact in the Pampa biome.
Assuntos
Ração Animal , Metano , Ração Animal/análise , Animais , Brasil , Bovinos , Dieta , Ecossistema , PradariaRESUMO
O objetivo neste estudo foi avaliar os componentes não-integrantes da carcaça de novilhos superjovem e jovem terminados em confinamento. Foram utilizados 24 novilhos castrados, 12 com idade média inicial de 8,1 meses e 12 com 20 meses, pertencentes às categorias superjovem e jovem, respectivamente, e abatidos com idade média de 13,1 e 22 meses. O peso de carcaça estipulado foi de 180 kg e a espessura de gordura subcutânea mínima pretendida foi de 3 mm. O peso de carcaça e a espessura de gordura subcutânea reais foram de 180,30 kg e 3,08 mm e 187,39 kg e 2,94 mm, respectivamente, para novilhos jovens e superjovens. Os animais jovens apresentaram maior peso absoluto e relativo dos pulmões (p < 0,05) em comparação aos superjovens (3,96 e 3,37 kg; 1,31 e 1,15%, respectivamente). Os animais jovens apresentaram maior (p < 0,05) peso absoluto (11,55 e 10,41 kg) e relativo ao peso de corpo vazio (3,83 e 3,56%) do conjunto total dos órgãos vitais em comparação aos animais superjovens. A categoria jovem apresentou maior (p < 0,05) peso absoluto e relativo para peso de corpo vazio para todos os componentes avaliados do trato gastrintestinal, exceto para o abomaso. Estas diferenças explicam, em parte, o maior rendimento de carcaça dos novilhos superjovens em relação aos joven.
The objective of this study was to evaluate the non-carcass body components of steers and young steers finished on feedlot. Twenty-four steers were used, being twelve with initial mean age of 8.1 months (super young) and twelve with initial mean age of 20 months (young). The animals were slaughtered at 22 and 13.1 months of age, respectively. The desired carcass weight was 180 kg with a minimum of 3 mm backfat thickness. Actual carcass weight and backfat thickness were 180.30 kg and 3.08 mm and 187.39 kg and 2.94 mm, respectively, for steers and young steers. Steers had higher (p < 0.05) lung weight in absolute and relative terms than the young steers (3.96 versus 3.37 kg and 1.31 versus 1.15%, respectively). The steers had higher (p < 0.05) absolute (11.55 versus 10.41 kg) and relative weight (3.83 versus 3.56%) of the total vital organs than the young steers. The absolute weight and relative to empty body weight for total gastrointestinal tract were higher for the steer category (p < 0.05), except for abomasum. These differences partially explain the higher carcass dressing percentage of the young steerss.
Assuntos
Animais , Adulto Jovem , Bovinos , Bovinos , Bovinos/anatomia & histologia , Peso Corporal/fisiologia , Distribuição da Gordura Corporal/veterinária , Trato GastrointestinalRESUMO
O objetivo neste estudo foi avaliar os componentes não-integrantes da carcaça de novilhos superjovem e jovem terminados em confinamento. Foram utilizados 24 novilhos castrados, 12 com idade média inicial de 8,1 meses e 12 com 20 meses, pertencentes às categorias superjovem e jovem, respectivamente, e abatidos com idade média de 13,1 e 22 meses. O peso de carcaça estipulado foi de 180 kg e a espessura de gordura subcutânea mínima pretendida foi de 3 mm. O peso de carcaça e a espessura de gordura subcutânea reais foram de 180,30 kg e 3,08 mm e 187,39 kg e 2,94 mm, respectivamente, para novilhos jovens e superjovens. Os animais jovens apresentaram maior peso absoluto e relativo dos pulmões (p < 0,05) em comparação aos superjovens (3,96 e 3,37 kg; 1,31 e 1,15%, respectivamente). Os animais jovens apresentaram maior (p < 0,05) peso absoluto (11,55 e 10,41 kg) e relativo ao peso de corpo vazio (3,83 e 3,56%) do conjunto total dos órgãos vitais em comparação aos animais superjovens. A categoria jovem apresentou maior (p < 0,05) peso absoluto e relativo para peso de corpo vazio para todos os componentes avaliados do trato gastrintestinal, exceto para o abomaso. Estas diferenças explicam, em parte, o maior rendimento de carcaça dos novilhos superjovens em relação aos joven.(AU)
The objective of this study was to evaluate the non-carcass body components of steers and young steers finished on feedlot. Twenty-four steers were used, being twelve with initial mean age of 8.1 months (super young) and twelve with initial mean age of 20 months (young). The animals were slaughtered at 22 and 13.1 months of age, respectively. The desired carcass weight was 180 kg with a minimum of 3 mm backfat thickness. Actual carcass weight and backfat thickness were 180.30 kg and 3.08 mm and 187.39 kg and 2.94 mm, respectively, for steers and young steers. Steers had higher (p < 0.05) lung weight in absolute and relative terms than the young steers (3.96 versus 3.37 kg and 1.31 versus 1.15%, respectively). The steers had higher (p < 0.05) absolute (11.55 versus 10.41 kg) and relative weight (3.83 versus 3.56%) of the total vital organs than the young steers. The absolute weight and relative to empty body weight for total gastrointestinal tract were higher for the steer category (p < 0.05), except for abomasum. These differences partially explain the higher carcass dressing percentage of the young steerss.(AU)