Danielo J, McCarty K J, Tipton J E, Ricks R E, Long N M
Department of Animal and Veterinary Sciences, Clemson University, Clemson, SC 29634, USA.
Department of Animal and Veterinary Sciences, Clemson University, Clemson, SC 29634, USA.
Domest Anim Endocrinol. 2020 Jul;72:106427. doi: 10.1016/j.domaniend.2019.106427. Epub 2019 Dec 26.
The objective of this study was to determine the effects of an immunomodulatory feed ingredient during post-weaning on growth and cortisol concentrations of beef heifers. Commercial Angus heifers (n = 72) from 2 AI sires were blocked (n = 9) by BW and randomly assigned to one of 2 pens per block. Each pen (4 heifers/pen) per block was randomly assigned to either one of 2 treatments, Celmanax (CEL) or corn germ (CON). The heifers were fed a commercial total mixed ration (TMR) twice daily from d 0 to 60 to gain 0.75 kg/d. The feed was top-dressed once daily with either 72g of Celmanax (CEL) or corn germ (CON) per pen. Body weight (BW) was collected on d -1, 0, 15, 30, 45, 60, and 61. Blood samples were collected on d 0, 15, 30, 45, and 60. Two heifers per pen (n = 32) were randomly selected for a transportation challenge to evaluate stress response on d 62 or 63 of the study. Sixteen heifers (n = 8 CEL; n = 8 CON) were randomly selected for a corticotropin-releasing hormone/arginine vasopressin (CRH/AVP) challenge and an intravenous glucose tolerance test (IVGTT) on d 64 and 67 of the study. The pen was the experimental unit, and data were analyzed by ANOVA or repeated measures analysis as appropriate. Feed efficiency and BW gain were increased (P = 0.04) in CEL heifers compared to CON heifers. Serum cortisol concentrations were decreased (P < 0.01) in CEL heifers compared to CON heifers on d 30 to 60 post-weaning. Serum cortisol concentrations were decreased (P < 0.05) in CEL heifers compared to CON heifers throughout the transportation challenge. Serum cortisol concentrations were decreased (P < 0.05) in CEL heifers compared to CON heifers during the CRH/AVP challenge from 60 to 150 min post-infusion. Treatment did not influence (P = 0.29) plasma insulin or glucose (P = 0.63) concentrations during the IVGTT. In summary, supplementation of Celmanax post-weaning increased BW gain and reduced cortisol concentrations in challenged beef heifers.
本研究的目的是确定一种免疫调节饲料成分在断奶后对肉用小母牛生长和皮质醇浓度的影响。来自2头人工授精公牛的商用安格斯小母牛（n = 72）按体重（BW）进行分组（n = 9），并随机分配到每个组的2个围栏之一。每个组的每个围栏（每围栏4头小母牛）随机分配到2种处理之一，即Celmanax（CEL）或玉米胚芽（CON）。从第0天到第60天，小母牛每天饲喂两次商业全混合日粮（TMR），以达到每天增重0.75千克。每天给每围栏的饲料表面额外添加72克Celmanax（CEL）或玉米胚芽（CON）。在第-1、0、15、30、45、60和61天采集体重（BW）数据。在第0、15、30、45和60天采集血样。在研究的第62天或63天，从每个围栏中随机选择2头小母牛（n = 32）进行运输应激挑战，以评估应激反应。在研究的第64天和第67天，随机选择16头小母牛（n = 8 CEL；n = 8 CON）进行促肾上腺皮质激素释放激素/精氨酸加压素（CRH/AVP）应激挑战和静脉葡萄糖耐量试验（IVGTT）。围栏是实验单位，数据根据情况通过方差分析或重复测量分析进行分析。与CON小母牛相比，CEL小母牛的饲料效率和体重增加有所提高（P = 0.04）。与CON小母牛相比，CEL小母牛在断奶后第30至60天的血清皮质醇浓度降低（P < 0.01）。在整个运输应激挑战期间，与CON小母牛相比，CEL小母牛的血清皮质醇浓度降低（P < 0.05）。在CRH/AVP应激挑战期间，从输注后60至150分钟，与CON小母牛相比，CEL小母牛的血清皮质醇浓度降低（P < 0.05）。在IVGTT期间，处理对血浆胰岛素或葡萄糖浓度没有影响（P = 0.29和P = 0.63）。总之，断奶后补充Celmanax可增加受应激肉用小母牛的体重增加并降低皮质醇浓度。
