背景:关于补充微量矿物质对牛犊应激反应的影响知之甚少。
目的:研究可注射微量矿物质补充剂(ITM)对不同类型应激条件下牛犊应激反应的影响。
方法:30只断奶安格斯和安格斯杂交小牛。
方法:将纳入的小牛随机分为两组:ITM,15只小牛接受改良活病毒疫苗(MLV)和ITMSC,15只小牛接受MLV和盐水SC(CONT)。小牛暴露于3种类型的压力:MLV疫苗接种的压力(d0),鼻气雾剂与牛病毒性腹泻病毒-2(BVDV-2)攻击(d5),和肝活检(d26)。对小牛的体重和健康状况进行了监测。白细胞计数,血清皮质醇浓度([cort]),BVDV-2血清中和抗体(SNA),和CD4+的百分比,CD8+,WC1+,测量CD25+T淋巴细胞。
结果:血清皮质醇浓度([cort])与CD8百分比(rs=.50)有很强的相关性,BVDV2-SNA(rs=-.43),和WC1CD25+(rs=.41)细胞,和直肠温度(rs=0.40)。在气溶胶BVDV-2攻击后3天报告最高[cort]。BVDV-2攻击后3天,经ITM处理的小牛的血清[cort]降低,与CONT小牛相比,平均下降18.5ng/μL(95%置信区间[CI],-6.07至-31.3)。经ITM处理的小牛比CONT小牛更重、更健康(P<.01)。
结论:微量矿物质补充剂似乎对肉牛具有缓解压力的作用,可能对生长和健康表现产生积极影响。病毒暴露与高度压力有关,这被认为是一个重大的福利问题。
BACKGROUND: Little is known about the effects of trace mineral supplementation on the stress response in beef calves.
OBJECTIVE: To investigate the effect of injectable trace mineral supplementation (ITM) on the stress response in beef calves exposed to different types of stress.
METHODS: Thirty weaned Angus and Angus crossbred calves.
METHODS: The enrolled calves were randomly assigned to 2 groups: ITM, 15 calves received modified-live virus vaccine (MLV) and ITM SC and 15 calves received MLV and saline SC (CONT). The calves were exposed to 3 types of stress: the stress of MLV vaccination (d0), nasal aerosol with bovine viral diarrhea virus-2 (BVDV-2) challenge (d5), and liver biopsy (d26). The calves\' body weights and health status were monitored. Leukocyte counts, serum cortisol concentration ([cort]), BVDV-2 serum neutralizing antibodies (SNA), and percentages of CD4+ , CD8+ , WC1+ , and CD25+ T-lymphocytes were measured.
RESULTS: Serum cortisol concentration ([cort]) showed strong associations with the percentage of CD8+ (rs = .50), BVDV2-SNA (rs = -.43), and WC1CD25+ (rs = .41) cells, and rectal temperature (rs = .40). The highest [cort] was reported 3 days after aerosol BVDV-2 challenge. Serum [cort] was decreased in ITM-treated calves 3 days post-BVDV-2 challenge, compared with CONT calves, with an average decrease of 18.5 ng/μL (95% confidence interval [CI], -6.07 to -31.3). The ITM-treated calves were heavier and healthier (P < .01) than the CONT calves.
CONCLUSIONS: Trace mineral supplementation appears to have stress mitigation effects in beef cattle that may reflect positively on growth and health performance. Viral exposure is associated with a high degree of stress, which is considered a major welfare concern.