Veterinary Medicine Teaching and Research Center, School of Veterinary Medicine, University of California Davis, Tulare, California, United States of America.
Department of Medicine and Infectious Diseases, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt.
PLoS One. 2019 Nov 7;14(11):e0224987. doi: 10.1371/journal.pone.0224987. eCollection 2019.
Bunching is the term used to describe the protective aggregating behavior of cattle against the painful bites of stable flies (Stomoxys calcitrans), where cattle gather in a group with their heads to the center of the group and their tails to the outside to reduce stable fly attack. Both sexes of the stable fly feed on blood, and their painful bites negatively impact cattle health, productivity and welfare. A longitudinal study was conducted from April to July 2017 to estimate the stable fly activity on 20 California dairies (average herd size = 2466 ± 1050), to determine stable fly activity that induced bunching, and to evaluate the association between management and environmental factors, and cattle bunching. Stable fly activity was recorded weekly using trap counts and leg counts. Data was analyzed using linear mixed models with odds ratio. Cattle bunching at the dairy level was predicted by mean trap counts of ≥150 flies/trap/week, while bunching at the pen level was predicted by mean leg counts >1 fly/leg/cow or mean trap counts >50 flies/trap/week for traps closest to the pen. Additional risk factors predicting cattle bunching at the dairy level were study week (May/June vs July), presence of crops adjacent to dairy >2 sides, and feeding wet distillers grain. Additional risk factors predicting cattle bunching at the pen level were study week (May/June vs July), ambient temperature ≤30°C, pen design (freestall vs open dry lot or bedded pack), production status (lactating/dry vs close-up), presence of crops surrounding cattle pens, feeding rations containing molasses. Cattle bunching was reduced at the pen level by relative humidity >50%, and when the cattle pen was surrounded by other cattle pens or was bordered by a main road. At the dairy level, removal of manure along fence lines of cattle pens was protective against cattle bunching.
聚集是指牛为了躲避厩蝇（Stomoxys calcitrans）的叮咬而采取的一种保护性聚集行为，即在厩蝇叮咬时牛群聚集在一起，头朝中心，尾巴朝外，以减少厩蝇的攻击。厩蝇的雌雄两性都以血液为食，它们的叮咬会对牛的健康、生产力和福利产生负面影响。本纵向研究于 2017 年 4 月至 7 月在加利福尼亚州的 20 个奶牛场进行，旨在估算厩蝇的活动情况（平均牛群规模=2466±1050），确定引起聚集的厩蝇活动，并评估管理和环境因素与牛群聚集的关系。每周使用诱捕器计数和腿部计数来记录厩蝇的活动情况。使用线性混合模型和比值比进行数据分析。奶牛场水平的牛群聚集由每周每诱捕器≥150 只厩蝇预测，而畜栏水平的牛群聚集由每只牛的腿部计数＞1 只/牛或最靠近畜栏的诱捕器每周计数＞50 只/诱捕器预测。在奶牛场水平预测牛群聚集的其他风险因素包括研究周（5 月/6 月与 7 月）、奶牛场两侧有作物相邻以及使用湿酒糟。在畜栏水平预测牛群聚集的其他风险因素包括研究周（5 月/6 月与 7 月）、环境温度≤30°C、畜栏设计（有卧床或无卧床）、生产状态（泌乳/干奶与产犊）、畜栏周围有作物、饲料中含有糖蜜。畜栏水平的牛群聚集可通过相对湿度＞50%、畜栏周围有其他畜栏或畜栏与主要道路相邻来减少。在奶牛场水平，沿畜栏围栏清除粪便可预防牛群聚集。
