Department of Forage Plants and Agrometeorology, Federal University of Rio Grande do Sul (UFRGS), 7712 Bento Gonçalves Ave., Porto Alegre, RS 91540-000, Brazil.
Brazilian Agricultural Research Corporation (Embrapa - CPPSUL), BR-153, Bagé, Brazil.
Sci Total Environ. 2021 Aug 1;780:146582. doi: 10.1016/j.scitotenv.2021.146582. Epub 2021 Mar 19.
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 CH 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 day (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). Average daily gain (kg LW day) 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 year 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 CH emissions remained constant around 150 g day for the two highest forage allowances and decreased to 118 and 107 g day 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.
我们检验了一个假设，即通过调整饲料允许量来改善草地结构，从而使肉牛增加采食量和活重（LW），并降低潘帕斯生物群落原生草原生态系统中每单位 LW 增重和单位面积的 CH 排放量。该实验于 2012 年和 2013 年在巴西南部进行。实验设计为随机完全区组设计，有两个重复。处理包括五种不同的原生草原饲料允许量：4、8、8-12、12 和 16 kg 干物质（DM）/100 kg LW 天（或%LW）。8-12%LW 处理的春季 LW 允许量为 8%，夏季、秋季和冬季 LW 允许量为 12%。通过改变放牧率（kg LW ha）来控制饲料允许量。对于 12%和 16%LW 的饲料允许量，平均日增重（kg LW 天）较高，但在 8%LW 时降低，在 4%LW 处理时达到最低值（p<0.001）。LW 增重公顷年最大的是 8-12%LW 的饲料允许量（p<0.001）。饲料 DM 摄入量在 12%LW 的饲料允许量时达到峰值（p=0.005）。对于两个最高的饲料允许量，个体 CH 排放量保持在 150 g 天左右，而在 8%和 4%LW 的饲料允许量下，排放量分别降低到 118 和 107 g 天（p=0.002）。单位 LW 增重和单位面积的排放量受动物生产力变化的驱动，随着饲料允许量的增加而减少（p=0.001 和 p=0.040）。我们建议，在潘帕斯生物群落中，春季的饲料允许量应为 8%LW，其余时间应为 12%LW，以最佳平衡动物生产和环境影响。
