This study investigated the effects of feeding an avian-derived polyclonal antibody preparation (PAP; CAMAS, Inc.) against Streptococcus bovis, Fusobacterium necrophorum, and lipopolysaccharides (LPS; 40%, 35%, and 25% of the preparation, respectively) on immune responses (haptoglobin [Hp], serum amyloid A [SAA], rectal temperature [RT], leukocyte counts, and expression of cell adhesion molecules cluster of differentiation [CD] CD11b, CD14, and CD62L) of beef steers during a 21-d step-up adaptation to a high-grain diet. Eight ruminally cannulated Angus crossbred beef steers (658 ± 79 kg of BW) were assigned in a cross-over design and transitioned from a diet containing bermudagrass hay (Cynodon dactylon (L.) Pers.) ad libitum plus 0.45 kg/d of molasses with 0 (CON) or 3 g of PAP to a high-grain diet. Transition consisted of three 7-d steps of increased inclusion of cracked corn (35%, 60%, and 82% of the diet dry matter for STEP1, STEP2, and STEP3, respectively). On each transition day and 7 d after STEP3 (STEP3-7d), RT was obtained every 3 h for a total of 24 h, whereas blood was collected on days 0, 1, and 3, relative to diet transition. There were no effects of PAP inclusion in any of the blood parameters (P > 0.11). However, a tendency for day effect (P = 0.10) was observed for concentrations of Hp, which were greater on days 3 and 7 vs. day 0 relative to the second diet transition (STEP2). Plasma concentrations of SAA were greater on days 1, 3, and 7 compared to day 0 during STEP1 (P = 0.01), while during STEP2 and STEP3, SAA concentrations increased (P < 0.01) from day 0 to 3. During STEP2, PAP steers tended to have lower (P = 0.08) RT than CON steers. Neutrophil and monocyte counts were the least during STEP3 (P < 0.01), whereas expression of CD11b and CD62L was the least through forage feeding (P < 0.01). Concentration of starch in the diet was correlated to all the variables tested (P ≤ 0.01), except for the percentage of B cells (P = 0.22). Yet only ruminal pH, RT, monocyte, and neutrophil counts presented strong correlation coefficients. In conclusion, the step-up transition from forage to high-grain diets triggered systemic inflammation in beef steers as observed by increased plasma concentrations of Hp, SAA, and expression on adhesion molecules in leukocytes. However, feeding polyclonal antibody preparations against S. bovis, F. necrophorum, and LPS did not provide benefits to mitigate inflammation.

中文翻译：

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禽类多克隆抗体制剂作为饲料添加剂对肉牛的影响：升级过渡饮食期间的免疫反应


本研究调查了饲喂禽源多克隆抗体制剂（PAP；CAMAS, Inc.）对牛链球菌、坏死梭杆菌和脂多糖（LPS；分别占制剂的 40%、35% 和 25%）的影响21-21 牛的免疫反应（触珠蛋白 [Hp]、血清淀粉样蛋白 A [SAA]、直肠温度 [RT]、白细胞计数和细胞粘附分子分化簇 [CD] CD11b、CD14 和 CD62L 的表达） d 逐步适应高谷物饮食。将 8 头瘤胃插管安格斯杂交小公牛（体重 658 ± 79 公斤）分配到交叉设计中，并从含有百慕大干草 (Cynodon dactylon (L.) Pers.) 随意加 0.45 公斤/天糖蜜的饮食转变为在高谷物饮食中添加 0 (CON) 或 3 g PAP。过渡包括增加碎玉米含量的三个 7 天步骤（STEP1、STEP2 和 STEP3 分别占日粮干物质的 35%、60% 和 82%）。在每个过渡日和第 3 步 (STEP3-7d) 后 7 天，每 3 小时获得一次 RT，总共 24 小时，而与饮食过渡相关的第 0、1 和 3 天则收集血液。 PAP 纳入对任何血液参数均没有影响 (P > 0.11)。然而，观察到 Hp 浓度存在日间效应趋势 (P = 0.10)，相对于第二次饮食转变 (STEP2)，第 3 天和第 7 天的 Hp 浓度高于第 0 天。在 STEP1 期间，第 1、3 和 7 天的 SAA 血浆浓度高于第 0 天 (P = 0.01)，而在 STEP2 和 STEP3 期间，SAA 浓度从第 0 天到第 3 天增加 (P < 0.01)。 PAP 阉牛的 RT 往往比 CON 阉牛低 (P = 0.08)。 STEP3 期间中性粒细胞和单核细胞计数最少 (P < 0.01)，而饲料喂养中 CD11b 和 CD62L 的表达最少 (P < 0.01)。除 B 细胞百分比 (P = 0.22) 外，饮食中淀粉的浓度与所有测试变量相关 (P ≤ 0.01)。然而，只有瘤胃 pH 值、RT、单核细胞和中性粒细胞计数呈现强相关系数。总之，通过 Hp、SAA 血浆浓度和白细胞粘附分子表达的增加观察到，从草料日粮向高谷物日粮的逐步过渡引发了小牛肉的全身炎症。然而，饲喂抗牛链球菌、坏死镰刀菌和脂多糖的多克隆抗体制剂并不能缓解炎症。