González L A, Ferret A, Manteca X, Ruíz-de-la-Torre J L, Calsamiglia S, Devant M, Bach A
Departament de Ciència Animal i dels Aliments, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
J Anim Sci. 2008 Jun;86(6):1446-58. doi: 10.2527/jas.2007-0675. Epub 2008 Feb 13.
The objective of the present study was to examine the effects of increasing the number of heifers per concentrate feeding place on performance, behavior, welfare indicators, and ruminal fermentation of feedlot heifers. Seventy-two Friesian heifers were used in a factorial arrangement, with 3 treatments and 3 blocks of similar BW. Treatments consisted of 2 (T2), 4 (T4), or 8 (T8) heifers per each place in the concentrate feeder (8 heifers/pen). Concentrate and straw were fed at 0830 h in individual feeders that allowed ad libitum consumption. During 6 periods of 28 d each, DMI and ADG were measured, and blood and rumen samples were taken. Fecal glucocorticoid metabolites and behavior were measured at periods 1, 3, and 6. Final BW, ADG, and G:F were not affected by treatments. Variability in final BW among heifers sharing the same pen tended to increase (P = 0.06) and concentrate intake decreased linearly as competition increased. The proportion of abscessed livers responded quadratically, being 8, 4, and 20% for T2, T4, and T8, respectively. Concentrate eating time decreased (P = 0.001) and eating rate increased (P = 0.05) linearly, whereas the variability between pen mates in concentrate eating time was greatest in T4 and T8. Increasing competition resulted in a quadratic response (P = 0.02) in daily lying time (greatest in T2), whereas standing time increased linearly (P = 0.02). The number of displacements among pen mates from the concentrate feeders, as well as the total sum of displacements, increased linearly (P < 0.05) with increasing competition. The pen average of fecal glucocorticoid metabolites was not affected by treatments (P >/= 0.16) but the pen's maximum concentration responded quadratically (P < 0.001), being greatest in T8, with dominant heifers being the most affected. Serum haptoglobin concentration increased linearly (P = 0.05) with competition, particularly within the most subordinate heifers. Increased competition reduced (P < 0.05) ruminal pH only in periods 1 and 2 and increased ruminal lactate (P = 0.02). Increasing competition at the concentrate feeders increased the variability in final BW but performance was not affected. Detrimental effects on animal welfare might be deduced from the altered feeding behavior, reduced resting time, and increased aggression. Ruminal lactate and blood haptoglobin indicate that the risk of rumen acidosis might increase with competition, whereas liver abscesses increased at 8 heifers per feeder.
本研究的目的是探讨增加每个精料饲喂位的小母牛数量对育肥牛的生产性能、行为、福利指标和瘤胃发酵的影响。72头弗里生小母牛按析因设计使用，有3种处理和3个体重相近的区组。处理包括在精料饲喂器中每个位置放置2头（T2）、4头（T4）或8头（T8）小母牛（8头/栏）。精料和秸秆于0830时在个体饲喂器中投喂，允许自由采食。在6个为期28天的时间段内，测定干物质采食量（DMI）和平均日增重（ADG），并采集血液和瘤胃样本。在第1、3和6期测定粪便糖皮质激素代谢物和行为。最终体重、ADG和料重比不受处理的影响。同栏小母牛之间最终体重的变异性有增加的趋势（P = 0.06），随着竞争加剧，精料摄入量呈线性下降。肝脏脓肿的比例呈二次方反应，T2、T4和T8组分别为8%、4%和20%。精料采食时间呈线性下降（P = 0.001），采食速度呈线性增加（P = 0.05），而T4和T8组同栏小母牛精料采食时间的变异性最大。竞争加剧导致每日躺卧时间呈二次方反应（P = 0.02）（T2组最长），而立时时间呈线性增加（P = 0.02）。随着竞争加剧，同栏小母牛从精料饲喂器处发生的驱赶次数以及驱赶总次数呈线性增加（P < 0.05）。同栏小母牛粪便糖皮质激素代谢物的平均值不受处理影响（P≥0.16），但同栏中的最大浓度呈二次方反应（P < 0.001），T8组最高，优势小母牛受影响最大。血清触珠蛋白浓度随着竞争呈线性增加（P = 0.05），尤其是在最从属的小母牛中。竞争加剧仅在第1和第2期降低了瘤胃pH（P < 0.05），并增加了瘤胃乳酸（P = 0.02）。精料饲喂器处竞争加剧增加了最终体重的变异性，但生产性能未受影响。采食行为改变、休息时间减少和攻击行为增加可能会对动物福利产生不利影响。瘤胃乳酸和血液触珠蛋白表明，瘤胃酸中毒的风险可能会随着竞争加剧而增加，而每个饲喂器8头小母牛时肝脏脓肿增加。
