1Animal Grassland Research and Innovation Centre,Teagasc,Grange,Dunsany,Co. Meath C15 PW93,Ireland.
2School of Agriculture and Food Science,University College Dublin,Belfield,Dublin 4,Ireland.
Animal. 2018 Nov;12(11):2391-2400. doi: 10.1017/S1751731118000034. Epub 2018 Feb 6.
Modifying finishing strategies within established production systems has the potential to increase beef output and farm profit while reducing greenhouse gas (GHG) emissions. Thus, the objectives of this study were to investigate the effects of finishing duration on animal performance of Holstein-Friesian (HF) bulls and steers and evaluate the profitability and GHG emissions of these finishing strategies. A total of 90 HF calves were assigned to a complete randomised block design; three bull and three steer finishing strategies. Calves were rotationally grazed in a paddock system for the first season at pasture, housed and offered grass silage ad libitum plus 1.5 kg DM of concentrate per head daily for the first winter and returned to pasture for a second season. Bulls were slaughtered at 19 months of age and either finished indoors on concentrates ad libitum for 100 days (19AL), finished at pasture supplemented with 5 kg DM of concentrate per head daily for 100 (19SP) or 150 days (19LP). Steers were slaughtered at 21 months of age and finished at pasture, supplemented with 5 kg DM of concentrate per head daily for 60 (21SP) and 110 days (21LP) or slaughtered at 24 months of age and finished indoors over the second winter on grass silage ad libitum plus 5 kg DM of concentrate per head daily (24MO). The Grange Dairy Beef Systems Model and the Beef Systems Greenhouse Gas Emissions Model were used to evaluate profitability and GHG emissions, respectively. Average daily gain during the finishing period (P<0.001), live weight at slaughter (P<0.01), carcass weight (P<0.05) and fat score (P<0.001) were greater for 19AL than 19SP and 19LP, respectively. Similarly, concentrate dry matter intake was greater for 19AL than 19SP; 19LP was intermediate (P<0.001). Live weight at slaughter (P<0.001), carcass weight (P<0.001), conformation score (P<0.05) and fat score (P<0.001) were greater for 24MO than 21SP and 21LP, respectively. During the finishing period concentrate dry matter intake was greater for 21LP than 21SP with 24MO intermediate; 542, 283 and 436 kg DM, respectively. Although pasture-based finishing strategies had lower gross output values, concentrate feed costs were also reduced thus net margin was greater than indoor finishing strategies. Reducing concentrate input increased GHG emissions for bulls and steers slaughtered at the same age, respectively. Although prolonging the finishing duration reduced GHG emissions for bull and steer production systems, finishing bulls and steers over a longer period at pasture did not enhance animal performance and profit.
改变既定生产系统中的育肥策略有可能增加牛肉产量和农场利润，同时减少温室气体（GHG）排放。因此，本研究的目的是调查育肥持续时间对荷斯坦-弗里森（HF）公牛和阉牛的动物性能的影响，并评估这些育肥策略的盈利能力和 GHG 排放。共有 90 头 HF 小牛被分配到完全随机分组设计中；三种公牛和三种阉牛育肥策略。小牛在第一个季节在牧场系统中轮牧，在第一个冬季被圈养并提供草青贮饲料自由采食，外加每头 1.5 公斤干物质的浓缩饲料，然后返回牧场进行第二个季节。公牛在 19 个月时被屠宰，要么在室内自由采食浓缩饲料 100 天（19AL），要么在牧场育肥，外加每天每头 5 公斤干物质的浓缩饲料 100 天（19SP）或 150 天（19LP）。阉牛在 21 个月时被屠宰，在牧场育肥，外加每天每头 5 公斤干物质的浓缩饲料 60 天（21SP）和 110 天（21LP），或在 24 个月时被屠宰，在第二个冬季在牧场自由采食草青贮饲料，外加每天每头 5 公斤干物质的浓缩饲料（24MO）。使用 Grange 奶牛牛肉系统模型和牛肉系统温室气体排放模型分别评估盈利能力和 GHG 排放。育肥期的平均日增重（P<0.001）、屠宰时的活体重（P<0.01）、胴体重（P<0.05）和脂肪评分（P<0.001）均高于 19AL 比 19SP 和 19LP。同样，19AL 的浓缩饲料干物质摄入量大于 19SP；19LP 处于中间水平（P<0.001）。屠宰时的活体重（P<0.001）、胴体重（P<0.001）、结构评分（P<0.05）和脂肪评分（P<0.001）均高于 24MO 比 21SP 和 21LP。在育肥期，21LP 的浓缩饲料干物质摄入量大于 21SP，而 24MO 处于中间水平；分别为 542、283 和 436 公斤干物质。虽然基于牧场的育肥策略的总产出值较低，但浓缩饲料成本也降低了，因此净利润率高于室内育肥策略。减少浓缩饲料的投入增加了公牛和阉牛在相同年龄屠宰时的温室气体排放。虽然延长育肥时间减少了公牛和阉牛生产系统的温室气体排放，但在牧场延长育肥时间并没有提高动物性能和利润。
