摘要
This study, conducted at São Paulo University feedlot, Dracena, Brazil, was designed to evaluate the effects of feeding virginiamycin (VM), as sole feed additive, to shorten the adaptation period to high-concentrate diets on feedlot performance of Nellore cattle. The experiment was designed as a completely randomized block, replicated 6 times (4 animals/pen), in which 120 18-mo-old yearling Nellore bulls (394.5 ± 19.0 kg) were fed in 30 pens for 112-d according to the treatments: sodium monensin (MON) and 14-d adaptation period, MON plus VM and 14-d adaptation, VM and 14-d adaptation; VM and 9-d adaptation, and VM and 6-d adaptation. MON and VM were added into diets at 30 and 25 ppm, respectively (DM basis). Three adaptation diets were fed over periods of 14-d, 9-d or 6-d with concentrate level increasing from 69% to 84% (DM basis). Contrasts were used to assess linear and quadratic effects of adaptation length in cattle fed only VM, and differences between cattle fed VM and adapted for 14-d and those fed MON or MON+VM. No treatment effect was observed (P>0.10) for final BW, ADG, and HCW. As the adaptation period lasted longer, DMI in kg (MON: 9.74, MON+VM: 9.70, VM 6-d: 9.92, VM 9-d: 10.43, VM 14-d: 10.03) was affected (P=0.02) quadratically, and final back fat thickness in mm increased linearly (MON: 5.61, MON+VM: 6.26, VM 6-d: 4.87, VM 9-d: 5.60, VM 14-d: 5.99), in cattle fed only VM. Cattle fed MON or MON+VM had improved G:F when compared those fed VM and adapted for 14-d (MON: 0.149, MON+VM: 0.146, VM 6-d: 0.138, VM 9-d: 0.135, VM 14-d: 0.135). However, cattle fed MON+VM had a decreased dressing percentage when compared to cattle fed VM and adapted for 14-d (53.7% vs. 55.0%). Thus, adaptation period should not be shortened when VM is fed as sole feed additive.
摘要译文
这项研究在巴西Dracena的圣保罗大学饲养场进行，旨在评估喂养牙氨霉素（VM）的影响，作为唯一的饲料添加剂，以缩短适应性期，以缩短对Nellore牛饲养场表现的高浓度饮食的适应性。该实验被设计为完全随机的块，复制了6次（4只动物/笔），其中120个18岁的Nellore Bulls（394.5±19.0 kg）在30支钢铁中以112-D的速度喂食30支钢笔。 ：Monensin（MON）和14-D适应周期，MON PLUS VM和14-D适应，VM和14-D适应； VM和9-D适应，以及VM和6-D适应。 MON和VM分别以30 ppm和25 ppm的饮食添加到饮食中（DM基础）。在14-D，9-D或6-D的周期中，浓缩水平从69％增加到84％（DM基础），喂食三种适应饮食。对比度用于评估仅饲喂VM的牛的适应长度的线性和二次效应，以及饲喂VM的牛和适用于14-D的牛之间的差异，以及饲养的MON或MON+VM。对于最终BW，ADG和HCW，未观察到治疗效果（p> 0.10）。随着适应周期的持续时间，DMI在kg中（星期一：9.74，MON+VM：9.70，VM 6-D：9.92，VM 9-D：10.43：10.43，VM 14-D：10.03）受到影响（P = 0.02）四边形，毫米的最终背部脂肪厚度线性增加（MON：5.61，MON+VM：6.26，VM 6-D：4.87，VM 9-D：5.60：5.60，VM 14-D：5.99），仅饲喂VM。当比较饲料的VM并适用于14-D的牛喂养的牛或周一+VM改善了G：F（Mon：0.149，Mon+VM：0.146：0.146，VM 6-D：0.138：0.138，VM 9-D：0.135，VM 14 -d：0.135）。然而，与饲喂VM的牛相比，饲喂周一+VM的牛的敷料百分比降低，并适用于14-D（53.7％比55.0％）。因此，当VM作为唯一的饲料添加剂喂食时，不应缩短适应周期。