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Pasture-finishing of late-maturing bulls or steers in a suckler calf-to-beef system: Animal production, meat quality, economics, greenhouse gas emissions and human-edible food-feed efficiency
Agricultural Systems ( IF 6.6 ) Pub Date : 2023-05-11 , DOI: 10.1016/j.agsy.2023.103672
M. McGee, A.P. Moloney, E.G. O'Riordan, M. Regan, C. Lenehan, A.K. Kelly, P. Crosson

CONTEXT

Demand for efficient sustainably-produced ‘grass-fed’ beef is increasing. Steers predominate in pasture-based systems. Bulls are inherently more efficient than steers but are usually produced indoors on concentrate-based rations rather than at pasture.

OBJECTIVE

Evaluate the animal productivity, meat quality, financial performance, greenhouse gas (GHG) production and human-edible protein (HEP) efficiency of suckler calf-to-beef systems, in which male progeny were finished as bulls or steers at pasture, with or without concentrate supplementation, at 19.5 months-of-age.

METHODS

Weaned suckler male cattle, produced as either bulls or steers, were offered grass silage and supplementary barley-soybean meal-based concentrates during a ‘backgrounding’ phase, and then assigned to one of two finishing strategies: grazed pasture-only for 192-days (G-O) or pasture-only for 95 days followed by pasture supplemented with 3.2 kg concentrate dry matter daily for 97 days (G-C). The experimental data generated were used to parameterise a whole-farm systems model and the productivity, profitability and GHG production of suckler calf-to-beef systems (encompassing cows, replacement heifers, female and male - bulls vs. steers - progeny) were evaluated.

RESULTS AND CONCLUSIONS

Bulls had a heavier carcass (+44 kg), greater kill-out proportion (+14 g/kg) and carcass conformation score (+1.6 units, scale 1–15), a lower carcass fat score (−2.3, scale 1–15), darker muscle and less yellow subcutaneous fat than steers. Concentrate supplementation increased daily live-weight gain (+0.36 kg), carcass weight (+37 kg), kill-out proportion (+12 g/kg), carcass conformation score (+1.1 units) and fat score (+1.0). Meat tenderness, texture and acceptability were lower for bulls than steers. Profitability of suckler calf-to-beef systems was greater where male progeny were finished as bulls rather than steers, and for G-C than G-O. The GHG emissions (CO2 eq) per cow were lower for steer compared to bull systems, and for G-O than G-C; however, when expressed per kg live-, carcass- and meat- weight, the opposite was found. Half of the GHG emissions within the calf-to-beef systems were attributed to the cow. The HEP ratio for G-O exceeded 1.0, but for G-C declined to 0.9 for steers and 1.0 for bulls: replacing cereal and soya-bean meal with by-products resulted in all systems having HEP efficiencies >1.0. Bull systems had lower meat eating quality, greater profit, lower GHG emissions intensity, and superior HEP efficiency than steers. Concentrate supplementation did not affect meat quality, increased profitability, and reduced GHG emission intensity and HEP.

SIGNIFICANCE

Consideration of unavoidable trade-offs in sustainability-related metrics between suckler beef systems is necessary.



中文翻译:

晚熟公牛或阉牛在乳牛小牛到牛肉系统中的牧场整理:动物生产、肉质、经济学、温室气体排放和人类可食用的食物饲料效率

语境

对高效、可持续生产的“草饲”牛肉的需求正在增加。阉牛在以牧场为基础的系统中占主导地位。公牛本质上比阉牛效率更高,但通常在室内生产,以浓缩为主的口粮,而不是在牧场。

客观的

评估乳牛小牛到牛肉系统的动物生产力、肉类质量、财务绩效、温室气体 (GHG) 产生和人类可食用蛋白质 (HEP) 效率,其中雄性后代在牧场上作为公牛或阉牛完成,使用或在 19.5 个月大时没有浓缩补充剂。

方法

在“背景”阶段,为公牛或阉牛生产的断奶乳牛提供青贮饲料和补充大麦豆粕浓缩物,然后分配到两种育肥策略之一:仅放牧 192 天(GO) 或仅放牧 95 天,然后每天补充 3.2 千克浓缩干物质的牧草,持续 97 天 (GC)。生成的实验数据用于参数化整个农场系统模型,并评估了乳犊牛到牛肉系统(包括奶牛、后备小母牛、雌性和雄性 - 公牛与阉牛 - 后代)的生产力、盈利能力和温室气体排放量.

结果和结论

公牛的胴体更重(+44 公斤),屠宰率更高(+14 克/公斤)和胴体形态评分(+1.6 单位,等级 1-15),胴体脂肪评分更低(-2.3,等级 1- 15), 比阉牛更黑的肌肉和更少的黄色皮下脂肪。精料补充增加了每日活重增加(+0.36 公斤)、胴体重(+37 公斤)、屠宰比例(+12 克/公斤)、胴体形态评分(+1.1 单位)和脂肪评分(+1.0)。公牛的肉嫩度、质地和可接受性低于阉牛。乳牛小牛到牛肉系统的盈利能力更高,其中雄性后代作为公牛而不是阉牛,并且对于 GC 比 GO。温室气体排放量(CO 2eq) 与公牛系统相比,每头奶牛的价格较低,而 GO 则低于 GC;然而,当以每千克活重、屠体重和肉重表示时,结果恰恰相反。小牛到牛肉系统中一半的温室气体排放归因于奶牛。GO 的 HEP 比率超过 1.0,但 GC 下降到 0.9(阉牛)和 1.0(公牛):用副产品代替谷物和豆粕导致所有系统的 HEP 效率 >1.0。公牛系统的肉食质量较低,利润较高,温室气体排放强度较低,HEP 效率高于牛。精料补充不会影响肉质,增加盈利能力,降低温室气体排放强度和 HEP。

意义

有必要考虑乳牛系统之间与可持续性相关的指标中不可避免的权衡。

更新日期:2023-05-12
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