Feedlot growth performance and carcass traits often differ between Holstein and dairy-beef crossbred calves. However, little is known about their performance and health during the growing phase when reared under similar conditions. This study aimed to compare purebred Holstein (n = 20) and Holstein x Angus crossbred (n = 20) steers from birth until the end of the grower phase. Male calves sourced from one commercial farm arrived at a calf rearing facility at 4.7 ± 1.94 d of age. Calves were fed milk replacer (24 % CP, 20% fat) twice daily at 12 % of birth body weight (BW) for the first 2 wk after arrival and 15 % BW thereafter until wk 6. Calves were gradually weaned from wk 7 to 9. Calves were offered starter (21 % CP, 28% starch) ad libitum until wk 12, and were fed a grower diet (15 % CP, 56 % starch) until wk 32. Milk intake was recorded daily and starter intake on a weekly basis. Once on the growing diet, feed intake was recorded daily using automated feed bins (Roughage Intake Control system, Hokofarm Group). Until wk 12, fecal and respiratory scores were recorded twice daily to estimate the incidence of disease, BW was measured weekly and frame measurements (hip and wither heights, and heart and chest girth) were recorded on wk 4, 7 and 12. From wk 12 to 32, BW and frame measurements were recorded monthly. Data were analyzed using PROC GLIMMIX (SAS 9.4), with breed as fixed, and calf and time as random effects. There were no differences between breeds in initial BW (P = 0.69), proportion of days with diarrhea (P = 0.21) or respiratory disease (P = 0.11), intake of milk (P = 0.45), starter (P = 0.83) or grower diet (P = 0.28). Crossbred calves tended to have greater average daily gain during the rearing phase (P = 0.07) and were growing 250 g/d faster than Holstein calves throughout the growing phase (P < 0.01). Thus, at the end of the growing phase, crossbred calves were 33.5 kg heavier than Holstein calves and had a better feed conversion rate (P < 0.01). During the growing phase, crossbred calves had larger heart and chest girths (P < 0.01) than Holstein calves, whereas hip and wither heights were higher (P < 0.01) for Holstein calves throughout the study. Overall, crossbred calves had greater average daily gain and improved feed conversion rate than Holstein calves during the growing phase, but it remains unknown if these differences will affect their feedlot performance.

中文翻译：

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509 荷斯坦牛和荷斯坦牛 x 安格斯犊牛从出生到生长期结束的生长和健康


荷斯坦牛和奶牛杂交犊牛的饲养场生长性能和胴体性状通常不同。然而，在类似条件下饲养时，人们对它们在生长阶段的表现和健康状况知之甚少。本研究旨在比较纯种荷斯坦牛 （n = 20） 和荷斯坦 x 安格斯杂交牛 （n = 20） 从出生到生长阶段结束。来自一个商业农场的雄性犊牛在 4.7 ± 1.94 天到达犊牛饲养设施。犊牛在到达后的前 2 周每天两次饲喂代乳品（24% CP，20% 脂肪），体重为 12%，此后饲喂 15% 体重，直到第 6 周。犊牛从第 7 周到第 9 周逐渐断奶。犊牛随意喂食起始饲料（21% CP，28% 淀粉）至 12 周，并饲喂生长日粮（15% CP，56% 淀粉）至 32 周。每天记录牛奶摄入量，每周记录发酵剂摄入量。一旦开始生长日粮，每天使用自动饲料箱（粗饲料摄入控制系统，Hokofarm Group）记录采食量。直到第 12 周，每天记录两次粪便和呼吸评分以估计疾病的发生率，每周测量 BW，并在第 4、7 和 12 周记录框架测量值（臀部和肩高，以及心脏和胸围）。从第 12 周到第 32 周，每月记录 BW 和帧测量值。使用 PROC GLIMMIX （SAS 9.4） 分析数据，品种为固定，犊牛和时间为随机效应。品种间在初始体重 （P = 0.69）、腹泻天数比例 （P = 0.21） 或呼吸系统疾病 （P = 0.11）、牛奶摄入量 （P = 0.45）、开食剂 （P = 0.83） 或生长者饮食 （P = 0.28） 方面没有差异。杂交犊牛在饲养阶段的平均日增重往往更高 （P = 0.07），并且在整个生长阶段比荷斯坦犊牛生长速度快 250 g/d（P < 0.01）。因此，在生长期结束时，杂交犊牛比荷斯坦犊牛重 33.5 公斤，饲料转化率更高 （P < 0.01）。在生长期，杂交犊牛的心围和胸围 （P < 0.01） 比荷斯坦犊牛大，而在整个研究过程中，荷斯坦犊牛的臀围和肩高更高 （P < 0.01）。总体而言，杂交犊牛在生长阶段的平均日增重高于荷斯坦犊牛，饲料转化率更高，但这些差异是否会影响其饲养场性能仍是未知数。