Terré Marta, Queiroz Oscar C M, Joergensen Jens N, Cappellozza Bruno I
Department of Ruminant Production, Institute of Agrifood Research and Technology (IRTA), Torre Marimon, 08140 Caldes de Montbui, Spain.
Novonesis, Lyngby 2800, Denmark.
J Dairy Sci. 2025 Oct;108(10):10888-10899. doi: 10.3168/jds.2025-26866. Epub 2025 Aug 6.
This experiment evaluated the effects of feeding a Bacillus-based direct-fed microbial (DFM) on the growth rates and metabolic responses of Angus × Holstein crossbred calves. After a 1-wk adaptation period, 80 calves were blocked by sex, initial BW (47 ± 5.1 kg, average ± SD), and age (15 ± 3.8 d, average ± SD) into the following treatments: (1) milk replacer (MR) with the addition of maltodextrin (CON; n = 40; 15 females and 25 males), or (2) MR with the addition of 1 g of a Bacillus-based DFM (BAC; n = 40; 16 females and 24 males) containing Bacillus paralicheniformis 809 and Bacillus subtilis 810 and 9 g of maltodextrin/head per day. Treatments were offered for 63 d and animals were raised in 8 pens of 10 calves each. The dose of BAC was applied with the first MR feeding through an automatic milk feeder, and calves were fed increasing amounts of MR until reaching 1.74 kg of MR at 13 d; this amount was maintained until 42 d, and it was gradually decreased until 63 d, when calves were completely weaned. Animals were followed one more week after weaning. Blood samples were collected from all calves at the beginning and at weaning for determination of different markers of growth, metabolism, and immunity. For all statistical analyses, calf was considered the experimental unit. The proportion of calves with fecal score >1 was greater in CON during wk 4 and 7 of the study, but greater for BAC than CON at wk 6. Calves from CON had a greater ADG on wk 8, whereas opposite results were observed on wk 9. For MR intake, CON calves had a greater intake on wk 1 and 2 than BAC, whereas total DMI was greater for CON on wk 2, but greater on wk 9 for BAC. Lastly, the same treatment × week interaction tended to be observed on feed efficiency (FE), as BAC calves had a greater FE on wk 1 and 2 than CON and tended to be greater on wk 3. At weaning, serum gamma-glutamyl transferase, total serum protein, and nonesterified fatty acid concentrations were greater in BAC, whereas serum glucose and haptoglobin concentrations tended to be greater and serum lactate concentration tended to be lower in BAC-fed calves. In summary, Bacillus spp. supplementation positively affected the FE of preweaning Angus × Holstein calves while also modulating their metabolic and immune responses. Nonetheless, additional studies are warranted to understand the metabolic pathways leading to such responses, if any.
本试验评估了饲喂基于芽孢杆菌的直接投喂微生物（DFM）对安格斯×荷斯坦杂交犊牛生长速度和代谢反应的影响。经过1周的适应期后，80头犊牛按性别、初始体重（47±5.1千克，平均值±标准差）和年龄（15±3.8天，平均值±标准差）进行分组，分为以下处理组：（1）添加麦芽糊精的代乳粉（CON；n = 40；15头雌性和25头雄性），或（2）添加1克基于芽孢杆菌的DFM（BAC；n = 40；16头雌性和24头雄性）的代乳粉，其中DFM含有解淀粉芽孢杆菌809和枯草芽孢杆菌810，每天每头添加9克麦芽糊精。处理持续63天，动物饲养在8个围栏中，每个围栏10头犊牛。BAC剂量在第一次投喂代乳粉时通过自动喂料器添加，犊牛逐渐增加代乳粉的摄入量，直到13天时达到1.74千克代乳粉；该摄入量维持到42天，然后逐渐减少，直到63天犊牛完全断奶。断奶后对动物再跟踪一周。在试验开始时和断奶时从所有犊牛采集血样，以测定生长、代谢和免疫的不同标志物。对于所有统计分析，犊牛被视为实验单位。在研究的第4周和第7周，CON组粪便评分>1的犊牛比例更高，但在第6周BAC组高于CON组。CON组犊牛在第8周的平均日增重更高，而在第9周观察到相反的结果。对于代乳粉摄入量，CON组犊牛在第1周和第2周的摄入量高于BAC组，而在第2周CON组的总干物质摄入量更高，但在第9周BAC组更高。最后，在饲料效率（FE）方面也观察到相同的处理×周交互作用，因为BAC组犊牛在第1周和第2周的FE高于CON组，在第3周也有更高的趋势。断奶时，BAC组血清γ-谷氨酰转移酶、总血清蛋白和非酯化脂肪酸浓度更高，而BAC组犊牛血清葡萄糖和触珠蛋白浓度有更高的趋势，血清乳酸浓度有更低的趋势。总之，补充芽孢杆菌属对断奶前安格斯×荷斯坦犊牛的FE有积极影响，同时也调节了它们的代谢和免疫反应。尽管如此，仍需要进一步研究以了解导致这些反应的代谢途径（如果存在的话）。
