The effects of divergent calf rearing diets and post-weaning pasture quality on growth, carcass traits, economics and the environment were investigated. Beef x dairy heifer calves were allocated to one of two rearing treatments, followed by a low (L)- or high (H) quality post-weaning pasture diet from 3 to 7 months old, in a 2 × 2 factorial design (n=50 per treatment). The R1 rearing treatment received 4 L milk/day for 5 weeks, then 2 L/day for two weeks plus concentrate pellets ad libitum for 7 weeks in group pens. These calves then grazed pasture from 7 weeks, with pellet-weaning at 12 weeks. The R2 rearing treatment were fed 8 L milk/day for 9 weeks, then 4 L for 2 weeks, weaning at 12 weeks, with ad libitum pasture outdoors after the first week. Cattle were managed as two groups, balanced for treatments, on a pasture-based diet from 7 months until slaughter at 19 to 25 months old. Calves offered the R1 diet grew slower than R2 calves with a 7 kg liveweight difference at 12 weeks (P<0.001) and an 11 kg difference at 7 months (P<0.001). Calves fed H pastures grew twice as fast as L fed calves from 3 to 7 months (P<0.001), providing a 31 kg liveweight advantage at 7 months. Treatment differences in liveweight were supported by differences in frame size, with liveweight differences largely maintained until slaughter. Treatments had minor effects on carcass traits and meat quality. Modelling of treatments from 12 weeks to slaughter showed H, and to a lesser extent R2 diets, may reduce nitrate leaching and methane emissions on beef farms compared to L and R1 diets.

研究了不同的犊牛饲养饮食和断奶后牧草质量对生长，car体性状，经济和环境的影响。牛x乳牛犊牛被分配到两种饲养方法之一，然后以2×2因子设计（3 = 7个月）断奶后低（L）-或高（H）质量的断奶后牧场饮食每次治疗50个）。R1养育处理组每天接受4升牛奶/天，持续5周，然后每天2升/天，持续2周，再加上任意剂量的浓缩丸7周。然后这些小牛从7周开始放牧，在12周断奶。R2饲养方法每天喂8 L牛奶，持续9周，然后4 L，持续2周，在12周时断奶，随意采食第一周后在户外放牧。从7个月到19至25个月大的牛被宰杀，以牧场为基础的饮食将牛分为两组，各组进行均衡处理。提供R1饮食的犊牛生长速度比R2犊牛慢，在12周时的活重差异为7 kg（P <0.001），在7个月时的活重差异为11 kg（P <0.001）。从3个月到7个月，饲喂H牧场的犊牛的生长速度是L饲喂的犊牛的两倍（P <0.001），在7个月时提供31 kg的活体重。活重的治疗差异由框架大小的差异支持，活重的差异在屠宰前基本保持不变。处理对car体性状和肉质影响较小。从12周到屠宰的治疗模型显示H饮食，R2饮食的程度较小，