We evaluated effects of preconditioning on performance and health of beef calves raised and finished in the Great Plains. In experiment 1, calves were preconditioned for 0, 15, or 45 d and vaccinated against BRD-causing pathogens 14 d before maternal separation or after feedlot arrival. During receiving and finishing, preconditioned calves had greater DMI and ADG than non-preconditioned calves; however, timing of BRD vaccination did not affect animal health. In experiment 2, calves were vaccinated against BRD pathogens 0, 1, 2, or 3 times during a 30-d preconditioning program. Vaccination for BRD, regardless of degree, improved health during preconditioning; however, DMI, ADG, and G:F during preconditioning, receiving, and finishing were unaffected by degree of vaccination. In experiment 3, calves were preconditioned for 30 d, shipped 4 h to an auction facility, commingled for 12 h, and transported 4, 8, or 12 h to a feedlot. Feedlot performance and health of beef calves were not affected by transport of up to 12 h following auction-market commingling. In experiment 4, beef calves were subjected to 1 of 3 ranch-of-origin preconditioning programs: drylot weaning + abrupt dam separation, pasture weaning + fence-line contact with dams, and pasture weaning + fence-line contact with dams + supplemental feed delivered in a bunk. Drylot-weaned calves gained more weight during preconditioning. Unsupplemented, pasture-weaned calves had the least ADG during receiving but had greater ADG during finishing and had carcass characteristics similar to other treatments. In experiment 5, we evaluated performance of early-weaned beef calves fed grain-based diets with DMI adjusted to achieve ADG of 0.45, 0.91, or 1.36 kg/d during an 84-d growing period. Calves fed at restricted rates did not exhibit improved G:F relative to full-fed counterparts. In addition, there appeared to be limitations associated with predicting DMI and ADG of light-weight, early-weaned calves fed a grain-based diet.
展开▼
机译：我们评估了预处理对在大平原饲养和加工的小牛犊的性能和健康的影响。在实验1中，对小牛进行0、15或45 d的预处理，并在母体分离之前或育肥场到来之后的14 d接种针对引起BRD的病原体。在收割和整理过程中，预处理小牛的DMI和ADG高于未预处理小牛。但是，BRD疫苗的接种时间不会影响动物健康。在实验2中，在30天的预处理程序中，将小牛接种BRD病原体0、1、2或3次。 BRD疫苗接种，无论其程度如何，均可在预处理期间改善健康状况；但是，预处理，接收和完成过程中的DMI，ADG和G：F不受疫苗接种程度的影响。在实验3中，将犊牛进行30天的预处理，将其运送到拍卖场4小时，混合12小时，然后将4、8或12小时运送到饲养场。拍卖市场混合后长达12小时的运输不会影响肉牛的饲养性能和健康。在实验4中，对牛犊进行3种牧场预处理程序中的1种：干地断奶+突然水坝分离，牧场断奶+与水坝围栏接触，以及牧场断奶+与水坝围栏接触+补充饲料双层铺在预处理过程中，断奶的断奶犊牛体重增加。未补给的，断奶的断奶犊牛在接受过程中的ADG最少，但在精加工过程中的ADG更高，car体特征与其他处理类似。在实验5中，我们评估了饲喂谷物基日粮的早期断奶小牛的性能，将其DMI调整为在84天的生长期内平均日增重达到0.45、0.91或1.36 kg / d。相对于全喂食的同龄牛，以受限的速度喂食的犊牛的G：F没有改善。此外，在以谷物为基础的饮食中，预测轻型断奶小牛的DMI和ADG似乎存在局限性。
展开▼
