Silva Gleise M, Podversich Federico, Schulmeister Tessa M, Santos Erick R S, Sanford Carla, Siqueira Michelle C B, DiLorenzo Nicolas
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
Department of Animal Sciences, North Florida Research and Education Center, University of Florida, Marianna, FL 32446, USA.
Transl Anim Sci. 2022 May 20;6(2):txac070. doi: 10.1093/tas/txac070. eCollection 2022 Apr.
This study investigated the effects of feeding an avian-derived polyclonal antibody preparation (PAP; CAMAS, Inc.) against , , and lipopolysaccharides (40%, 35%, and 25% of the preparation, respectively) on ruminal fermentation [pH, ammonia-N (NH-N), lactate, and volatile fatty acids (VFA)] of beef steers during a 21-d step-up diet adaptation. Eight ruminally cannulated Angus crossbred beef steers (658 ± 79 kg of body weight) were assigned in a crossover design to be transitioned from a diet containing ad libitum bermudagrass hay [ (L.) Pers.] plus 0.45 kg/d (as fed) of molasses with 0 (CON) or 3 g of PAP (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 DM for STEP1, STEP2, and STEP3, respectively). On each transition day and 7 d after STEP3 (STEP3-7d), ruminal fluid samples were obtained every 3 h for 24 h. Feeding 3 g of PAP daily increased ( < 0.01) average ruminal pH during STEP3 compared with CON steers (5.6 vs. 5.4 ± 0.05, respectively). During STEP1, NH-N concentration was greater ( < 0.01; 9.4 vs. 6.8 ± 0.74 mM, respectively), and time (min/d) and area (time × pH) of ruminal pH below or equal to 5.2 was lesser ( ≤ 0.03) for steers consuming PAP compared with steers assigned to CON treatment (33.4 vs. 73.3 ± 21.7 min/d and 187.4 vs. 406.3 ± 119.7 min × pH/d, respectively). Steers consuming PAP had greater acetate:propionate ratio at 0, 3, and 6 h relative to diet change compared with CON (2.42, 2.35, 2.29 vs. 1.66, 1.79, and 1.72 ± 0.17, respectively), whereas butyrate molar proportions increased ( = 0.02; 17.1 vs. 11 ± 1.58 mol/100 mol for CON and PAP, respectively) when PAP was not fed at STEP2. Total ruminal lactate concentrations were not affected by PAP feeding ( > 0.11). In conclusion, feeding 3 g/d of polyclonal antibody preparation against , and lipopolysaccharides was effective in increasing ruminal pH, A:P ratio, and NH-N concentrations, possibly attenuating the risks of ruminal acidosis in steers during the step-up transition from forage to high-grain diets.
本研究调查了在21天的逐步日粮适应期内，给肉牛饲喂一种禽源多克隆抗体制剂（PAP；Camas公司），该制剂针对[具体物质未明确写出]和脂多糖（分别占制剂的40%、35%和25%）对瘤胃发酵[pH值、氨态氮（NH-N）、乳酸和挥发性脂肪酸（VFA）]的影响。八头装有瘤胃瘘管的安格斯杂交肉牛（体重658±79千克）采用交叉设计，从自由采食百慕大干草[（L.）Pers.]加0.45千克/天（按饲喂量计）糖蜜且添加0（对照，CON）或3克PAP（PAP组）的日粮过渡到高谷物日粮。过渡过程包括三个7天的阶段，逐步增加破碎玉米的添加量（分别为第1阶段、第2阶段和第3阶段日粮干物质的35%、60%和82%）。在每个过渡日以及第3阶段后的第7天（第3阶段-7天），每隔3小时采集瘤胃液样本，共采集24小时。与对照肉牛相比，每天饲喂3克PAP可使第3阶段的瘤胃平均pH值升高（P<0.01）（分别为5.6和5.4±0.05）。在第1阶段，采食PAP的肉牛氨态氮浓度更高（P<0.01；分别为9.4和6.8±0.74毫摩尔），且与对照处理的肉牛相比，采食PAP的肉牛瘤胃pH值低于或等于5.2的时间（分钟/天）和面积（时间×pH值）更少（P≤0.03）（分别为33.4和73.3±21.7分钟/天以及187.4和406.3±119.7分钟×pH值/天）。与对照相比，采食PAP的肉牛在日粮改变后0、3和6小时的乙酸:丙酸比值更高（分别为2.42、2.35、2.29和1.66、1.79、1.72±0.17），而在第2阶段不饲喂PAP时，丁酸摩尔比例增加（P = 0.02；对照和PAP组分别为11±1.58和17.1摩尔/100摩尔）。瘤胃总乳酸浓度不受PAP饲喂的影响（P>0.11）。总之，每天饲喂3克针对[具体物质未明确写出]和脂多糖的多克隆抗体制剂可有效提高瘤胃pH值、乙酸:丙酸比值和氨态氮浓度，可能降低肉牛从牧草日粮逐步过渡到高谷物日粮期间瘤胃酸中毒的风险。
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