Legume inclusion or nitrogen fertilization on Aruana grass overseeded with temperate grasses: Performance, carcass characteristics, and fatty acid profile of the meat of beef steers

ABSTRACT The objective of our study was to evaluate the effect of the use of legume (Arachis pintoi) or nitrogen fertilization on animal performance, characteristics of carcass and meat, and fatty acids profile of crossbred steers on Megathyrsus maximus cv. Aruana pasture, overseeded with temperate grasses. The experimental design was completely randomized, with three treatments and three replicates. The experiment was carried out from June to October (127 d). The treatments were: Low-N: 100 kg of N/ha; Medium-N: 200 kg of N/ha; and Legume: Arachis pintoi + 100 kg of N/ha. The pasture with higher nitrogen fertilization (N200) showed a more significant forage mass yield. The mixed grass with legumes presented a higher concentration of saturated fatty acids and saturated:unsaturated ratio in the meat. However, the grass pastures resulted in a higher content of unsaturated fatty acids in the meat. The other pasture variables, and characteristics of carcass and meat were not influenced by the treatments. The increase in nitrogen fertilization, from 100 to 200 kg/ha, and Arachis pintoi mixed with Aruana grass pasture overseeded with black oat and ryegrass does not affect the daily weight gain and the carcass and meat characteristics of the steers. The grass-legume mixture decreases the total concentration of unsaturated fatty acids in meat without influencing the concentration of polyunsaturated fatty acids.

摘要 本研究旨在评估施用平托花生（Arachis pintoi）或氮肥，对补播温带禾草的巨象草（Megathyrsus maximus cv. Aruana）牧场上的杂交阉牛的生产性能、胴体与肉质特性以及脂肪酸谱的影响。实验采用完全随机设计，设置3个处理组与3次重复，实验周期为6月至10月（共计127天）。处理组分别为：低氮组（Low-N）：每公顷施加100kg氮肥；中氮组（Medium-N）：每公顷施加200kg氮肥；豆科组：平托花生+每公顷100kg氮肥。结果表明，高氮肥施用量组（N200）的牧草生物量显著更高。豆科-禾草混播牧场的肉中饱和脂肪酸浓度及饱和/不饱和脂肪酸比值更高；而纯禾草牧场的肉中不饱和脂肪酸含量则更高。其余牧场指标、胴体与肉质特性均不受处理组影响。将氮肥施用量从100kg/ha提升至200kg/ha，以及在补播黑燕麦与黑麦草的阿鲁阿纳巨象草牧场中混播平托花生，均不会对阉牛的日增重及胴体与肉质特性产生影响。豆科-禾草混播会降低肉中不饱和脂肪酸的总浓度，但不影响多不饱和脂肪酸的浓度。