Montevecchio Ana B, Jones Kristi L, Galvão Klibs N, Casaro Segundo, Maunsell Fiona, Liu Ting, Jeong Kwangcheol C, Chebel Ricardo C
Department of Large Animal Clinical Sciences, University of Florida, Gainesville, FL 32610, USA.
Department of Animal Sciences, University of Florida, Gainesville, FL 32610, USA.
J Anim Sci. 2025 Jan 4;103. doi: 10.1093/jas/skaf121.
Housing strategies to alleviate the negative effects of heat stress on the performance of pre-weaned dairy calves have become a focus of research in recent years. Experiments evaluating such strategies have focused on thermoregulatory responses, behavior, and performance. To date, no experiments have evaluated their effects on the microbiota of the upper respiratory tract. Understanding this relationship is crucial for assessing its impact on respiratory health, disease susceptibility, and calf well-being. We conducted an experiment to characterize nasal microbiota from calves housed outdoors, under a naturally ventilated barn, with and without the provision of fans. The experiment was conducted in a commercial dairy in southern GA. Male Holstein calves (n = 60) were assigned randomly at birth (day 0) to 1 of 3 treatments: hutch outdoors with 50% of its area covered with plywood (control = 20), hutch in an open-sided barn with no supplemental cooling (SH = 21), and hutch in an open-sided barn with ceiling fans (SHF = 19), and followed until 68 d of age. Following the removal of obvious debris from the nostrils, nasal swabs were collected from all calves on week 5 (35 ± 8.9 d) and 9 (63 ± 3.2 d) of life and qPCR and 16S rRNA sequencing was performed. Treatment did not affect total bacterial 16S gene copy numbers or alpha diversity (i.e., Shannon and Simpson indexes) at 5 or 9 wk of age. We observed differences, however, in the nasal microbiome structure at weeks 5 and 9 among treatments, with variations in the mean relative abundance (MRA) of certain bacterial genera. On week 5, SHF treatment had reduced MRA of Mycoplasma compared with control and SH treatments and greater MRA of Acinetobacter than calves in the SH treatment. On week 9, control calves had reduced MRA of Escherichia compared with SHF calves and greater Moraxella MRA compared with those in the SH and SHF treatments. We observed differences in nasal microbiome structure of pre-weaned dairy calves as a result of housing strategy. While the results presented herein suggest a potential link between housing conditions and the risk of respiratory disease, further research is necessary to investigate this hypothesis. Improved understanding of the impact of housing environment on respiratory health as well as on heat stress could help producers make informed management decisions to improve calf health and well-being.
近年来，减轻热应激对断奶前奶牛犊生长性能负面影响的饲养策略已成为研究重点。评估此类策略的实验主要集中在体温调节反应、行为和生长性能方面。迄今为止，尚无实验评估过这些策略对上呼吸道微生物群的影响。了解这种关系对于评估其对呼吸健康、疾病易感性和犊牛健康状况的影响至关重要。我们进行了一项实验，以表征在自然通风牛舍中饲养的犊牛的鼻腔微生物群，牛舍位于户外，有风扇和无风扇两种情况。该实验在佐治亚州南部的一家商业奶牛场进行。雄性荷斯坦犊牛（n = 60）在出生当天（第0天）随机分配到3种处理中的一种：室外棚舍，其面积的50%覆盖胶合板（对照组 = 20头）；开放式牛舍中的棚舍，无补充降温措施（SH组 = 21头）；开放式牛舍中的棚舍，配有天花板风扇（SHF组 = 19头），并跟踪至68日龄。在清除鼻孔中的明显杂物后，在犊牛生命的第5周（35 ± 8.9天）和第9周（63 ± 3.2天）从所有犊牛采集鼻拭子，并进行qPCR和16S rRNA测序。处理对5周龄或9周龄时的总细菌16S基因拷贝数或α多样性（即香农和辛普森指数）没有影响。然而，我们观察到在第5周和第9周时，不同处理之间的鼻腔微生物群结构存在差异，某些细菌属的平均相对丰度（MRA）有所变化。在第5周时，与对照组和SH组相比，SHF处理组的支原体MRA降低，与SH组犊牛相比，不动杆菌的MRA更高。在第9周时，与SHF组犊牛相比，对照组犊牛的大肠杆菌MRA降低，与SH组和SHF组相比，莫拉菌的MRA更高。我们观察到断奶前奶牛犊的鼻腔微生物群结构因饲养策略而异。虽然本文给出的结果表明饲养条件与呼吸道疾病风险之间可能存在联系，但需要进一步研究来验证这一假设。更好地了解饲养环境对呼吸健康以及热应激的影响，有助于生产者做出明智的管理决策，以改善犊牛的健康和福利。
