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.

这项研究的目的是确定断奶后免疫调节饲料成分对牛肉小母牛生长和皮质醇浓度的影响。来自2个AI父系的商品安格斯小母牛（n = 72）被BW阻拦（n = 9），并随机分配给每块2支。每块每笔（4头小母牛/笔）被随机分配给Celmanax（CEL）或玉米胚芽（CON）2种处理中的一种。小母牛每天从d 0到60喂两次商业总混合日粮（TMR），增重0.75 kg / d。每天对饲料进行一次追肥，每支笔使用72克Celmanax（CEL）或玉米胚芽（CON）。在d -1，0、15、30、45、60和61上采集体重（BW）。在d 0、15、30、45和60上采集血液样本。随机选择每支小母牛两个小母牛（n = 32）进行运输挑战，以评估研究的第62或63天的应激反应。在研究的第64和67天，随机选择16个小母牛（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）攻击和静脉葡萄糖耐量试验（IVGTT）。该笔是实验单位，并通过ANOVA或适当的重复测量分析来分析数据。饲料效率和体重增加 并通过ANOVA或适当的重复测量分析来分析数据。饲料效率和体重增加 并通过ANOVA或适当的重复测量分析来分析数据。饲料效率和体重增加与CON小母牛相比，CEL小母牛的P = 0.04）。断奶后第30至60天，CEL小母牛的血清皮质醇浓度与CON小母牛相比降低（P <0.01）。在整个运输挑战中，CEL小母牛的血清皮质醇浓度与CON小母牛相比降低（P <0.05）。在输注后60至150分钟的CRH / AVP攻击过程中，与CON小母牛相比，CEL小母牛的血清皮质醇浓度降低（P <0.05）。治疗未影响（P = 0.29）血浆胰岛素或葡萄糖（P= 0.63）IVGTT期间的浓度。总之，断奶后补充Celmanax可以增加牛犊母牛的体重增加和皮质醇浓度降低。