Sawyer J E, Mathis C P, Davis B
Department of Animal and Range Sciences, Clayton Livestock Research Center, Clayton 88415, USA.
J Anim Sci. 2004 Dec;82(12):3646-53. doi: 10.2527/2004.82123646x.
To evaluate production and economic effects of feeding management strategy and age on intensively managed culled beef cows, a study was conducted using 125 cows of British breeding blocked by age (Young = 3 and 4 yr olds; LowMid = 5 and 6 yr olds; HighMid = 7 and 8 yr olds; and Aged = 9 yr and older) and assigned to one of three steam-flaked corn based feeding strategies. Treatments were as follows: Conservative (CSV), 30% roughage throughout; Standard (STD), decrease roughage from 30 to 10% over 20 d; and Aggressive (AGR), decrease roughage from 30 to 10% over 10 d. There were four pens per treatment in a randomized complete block design. Cows were fed for a total of 54 d, and BW was measured on d 0, 14, 28, 42, and 54. Half the cows from each pen were randomly selected and slaughtered at a commercial abattoir, and carcass data were collected. Average daily gain, daily DMI, and G:F during each weigh period and across the entire feeding period were calculated. Over the 54-d feeding period, strategies that employed more energy-dense diets numerically increased ADG (1.28, 1.63, and 1.55 +/- 0.14 kg/d for CSV, STD, and AGR; P = 0.26) and decreased DMI (11.91, 10.74, and 10.89 +/- 0.27 kg/d for CSV, STD, and AGR; P = 0.05), such that G:F was lower for CSV than for STD or AGR (0.105, 0.150, and 0.141 +/- 0.010; P = 0.05). Carcass weight was least for the CSV strategy (298 kg) and greatest for STD (328 kg); AGR resulted in intermediate carcass weight (317 +/- 6 kg; P = 0.04). Total cost of gain was over 30% greater for CSV strategy than for STD or AGR strategies (P < 0.01). In many cases, block effects (age) had a greater effect on responses than treatments. Average daily gain, DMI, and G:F decreased linearly with age (P < 0.01). Hot carcass weight, dressing percent, and fat thickness decreased linearly with age (P < 0.03); yield grade decreased and carcass maturity attributes increased linearly with age (P < 0.02). Performance and intake differences resulted in linear increases in total cost of gain (P < 0.01) and breakeven price (P = 0.03) with increasing age. These data indicate advantages to more aggressive feeding management strategies for culled beef cows, although maximal intake may be achieved with higher-roughage diets. Despite management effects, an increase in market price above purchase price may be required for intensive feeding of culled beef cows to be a profitable enterprise.
为评估饲养管理策略和年龄对集约化管理的淘汰肉牛的生产及经济效应，使用125头英国品种的母牛进行了一项研究，这些母牛按年龄分组（年轻组=3岁和4岁；低中龄组=5岁和6岁；高中龄组=7岁和8岁；老龄组=9岁及以上），并被分配到三种基于蒸汽压片玉米的饲养策略之一。处理方式如下：保守组（CSV），全程粗饲料占比30%；标准组（STD），在20天内将粗饲料比例从30%降至10%；激进组（AGR），在10天内将粗饲料比例从30%降至10%。采用随机完全区组设计，每个处理设置四个栏位。母牛总共饲养54天，在第0、14、28、42和54天测量体重。从每个栏位中随机选择一半的母牛，在商业屠宰场屠宰，并收集胴体数据。计算每个称重期及整个饲养期的平均日增重、日干物质采食量和料重比。在54天的饲养期内，采用能量密度更高日粮的策略在数值上提高了平均日增重（CSV、STD和AGR组分别为1.28、1.63和1.55±0.14千克/天；P=0.26），并降低了日干物质采食量（CSV、STD和AGR组分别为11.91、10.74和10.89±0.27千克/天；P=0.05），使得CSV组的料重比比STD组或AGR组更低（分别为0.105、0.150和0.141±0.010；P=0.05）。胴体重以CSV策略最低（298千克），STD策略最高（328千克）；AGR策略的胴体重处于中间水平（317±6千克；P=0.04）。CSV策略的总增重成本比STD或AGR策略高出30%以上（P<0.01）。在许多情况下，区组效应（年龄）对反应的影响大于处理效应。平均日增重、日干物质采食量和料重比随年龄呈线性下降（P<0.01）。热胴体重、屠宰率和脂肪厚度随年龄呈线性下降（P<0.03）；产量等级下降，胴体成熟度指标随年龄呈线性增加（P<0.02）。性能和采食量的差异导致总增重成本（P<0.01）和盈亏平衡价格（P=0.03）随年龄线性增加。这些数据表明，对于淘汰肉牛采用更激进的饲养管理策略具有优势，尽管高粗饲料日粮可能实现最大采食量。尽管有管理效应，但要使淘汰肉牛的集约化饲养成为盈利企业，可能需要市场价格高于购买价格。
