Department of Animal Science, Division of Agricultural Sciences and Natural Resources, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater 74078, USA.
J Anim Sci. 2010 Jun;88(6):2179-88. doi: 10.2527/jas.2009-2006. Epub 2010 Feb 12.
Bovine viral diarrhea viruses (BVDV) have been isolated alone or in combination with other viral and bacterial pathogens in animals diagnosed with bovine respiratory disease (BRD), a disease causing major economic loss to the feedlot industry. The objective of this experiment was to determine the effects of Mannheimia haemolytica challenge after short-term exposure (72 h) to bovine viral diarrhea virus type 1b (BVDV1b) persistently infected (PI) calves on performance, N balance, and organ mass in finishing cattle. Treatments (6 steers/treatment; initial BW = 314 +/- 31 kg) were 1) steers not exposed to steers PI with BVDV nor challenged with M. haemolytica (control; CON); 2) steers exposed to 2 steers PI with BVDV1b (BVD) for 72 h; 3) steers intratracheally challenged with M. haemolytica (MH); or 4) steers exposed to 2 steers PI with BVDV1b for 72 h and challenged with M. haemolytica (BVD+MH). There were 12 h between exposure to PI steers and challenge with M. haemolytica. Steers were housed in metabolism stanchions during the first 5 d after the M. haemolytica challenge and on d 7 to 11, 28 to 32, and for 5 d before slaughter (average 119 d on feed) to determine N balance and were weighed every 28 d. At slaughter, carcass and organ mass data were collected. Data were analyzed as a randomized complete block design with a 2 x 2 factorial arrangement of treatments, and steer was used as the experimental unit. From d -3 (beginning of PI steer exposure) to 4, steers challenged with M. haemolytica had less (P = 0.04) ADG than steers not challenged with M. haemolytica. In addition, steers exposed to steers PI with BVDV tended (P = 0.09) to have less ADG and G:F across the entire finishing period than steers not exposed to BVDV. Before slaughter, retained N expressed as grams per day (P = 0.03) and as a percentage of N intake (P = 0.04) was less in BVD steers compared with steers not exposed to BVDV. There were no effects (P > 0.10) of BVDV exposure or M. haemolytica challenge on empty BW (EBW) or carcass characteristics. Expressed as a percentage of EBW, HCW was less (P = 0.02) and total offal weight was greater (P = 0.02) for steers challenged with M. haemolytica compared with steers not challenged. Results are in agreement with those reported in larger scale finishing studies and suggest that acute exposure to BRD-related pathogens can have long-term effects on animal performance.
牛病毒性腹泻病毒（BVDV）已在被诊断为牛呼吸道疾病（BRD）的动物中单独或与其他病毒和细菌病原体一起分离出来，这是一种给饲养场行业造成重大经济损失的疾病。本实验的目的是确定短期（72 小时）暴露于牛病毒性腹泻病毒 1b（BVDV1b）持续性感染（PI）小牛后感染曼海姆氏菌（M. haemolytica）挑战对育肥牛性能、氮平衡和器官质量的影响。处理（6 头/处理；初始体重=314 +/- 31 公斤）为 1）未接触 BVDV1b PI 牛且未感染 M. haemolytica 的牛（对照；CON）；2）72 小时内接触 2 头 BVDV1b PI 牛的牛（BVD）；3）气管内接种 M. haemolytica 的牛（MH）；或 4）72 小时内接触 2 头 BVDV1b PI 牛并感染 M. haemolytica 的牛（BVD+MH）。在接触 PI 牛和 M. haemolytica 挑战之间有 12 小时的间隔。在 M. haemolytica 挑战后的前 5 天和第 7 至 11 天、第 28 至 32 天以及屠宰前 5 天（平均在饲料上 119 天），牛被安置在代谢栏中，以确定氮平衡并每 28 天称重一次。在屠宰时，收集胴体和器官质量数据。数据作为具有 2 x 2 处理因子安排的随机完全块设计进行分析，以牛为实验单位。从第-3 天（PI 牛接触开始）到第 4 天，接受 M. haemolytica 挑战的牛的 ADG 较低（P = 0.04），而未接受 M. haemolytica 挑战的牛的 ADG 较高。此外，与未接触 BVDV 的牛相比，接触 BVDV PI 牛的牛整个育肥期的 ADG 和 G:F 均呈趋势（P = 0.09）较低。在屠宰前，以每天克数（P = 0.03）和以摄入氮的百分比表示的保留氮（Retained N）（P = 0.04）在 BVD 牛中均低于未接触 BVDV 的牛。BVDV 暴露或 M. haemolytica 挑战对空肠 BW（Empty BW）或胴体特征没有影响（P > 0.10）。以空肠 BW 的百分比表示，接受 M. haemolytica 挑战的牛的 HCW 较低（P = 0.02），总内脏重量较大（P = 0.02）。结果与更大规模育肥研究报告的结果一致，表明急性接触 BRD 相关病原体可能对动物性能产生长期影响。
