Maples William E, Brorsen B Wade, Peel Derrell, Hicks Britt
Department of Agricultural Economics, Mississippi State University, Starkville, MS, United States.
Department of Agricultural Economics, Oklahoma State University, Stillwater, OK, United States.
Front Vet Sci. 2022 Jul 22;9:947585. doi: 10.3389/fvets.2022.947585. eCollection 2022.
There is public pressure to reduce antimicrobial use in livestock production. Metaphylaxis usage raises special concern as it is given to a whole group of animals. The objective of this research was to determine the difference in cattle productivity and health (average daily gain, death loss, etc.) between cattle given metaphylaxis and those to which it was not given. Observational data were provided by a commercial feedlot in the Southern Great Plains region of the U.S.A. with an operating capacity >50,000 head. Cattle that received metaphylaxis treatment had substantially poorer health outcomes than those that did not. Cattle were more likely to have been given metaphylaxis treatment if they had a lower weight, were from a sale barn, or had been shipped long distances. Propensity score matching was used in an attempt to estimate the effect of metaphylaxis treatment on feedlot cattle. Propensity score matching was unable to overcome the endogeneity issues present in the data (endogeneity results from the animals being more likely to benefit from the treatment being the ones who received it). The dataset had information on cattle weight, state of purchase, and whether or not the cattle were from a sale barn, and so the feedlot must have based the treatment decision on information that was not recorded and therefore not included in the dataset. As an observational study, there are limitations in addition to data limitations, such as the possibility that the feedlot studied might not be representative of others. Even though the effect of metaphylaxis was not identified, the fact that it was unidentifiable supports the argument that the feedlot did treat the animals most likely to need metaphylaxis treatment. This should temper some fear of metaphylaxis treatment being overused and of antimicrobials being given needlessly.
减少畜牧业中抗菌药物使用存在公众压力。群体预防性用药引发了特别关注，因为它是对整群动物使用。本研究的目的是确定接受群体预防性用药的牛与未接受该用药的牛在生产性能和健康状况（平均日增重、死亡损失等）方面的差异。观测数据由美国大平原南部地区一家运营能力超过50000头牛的商业饲养场提供。接受群体预防性用药治疗的牛的健康状况明显比未接受治疗的牛差。体重较低、来自销售场或经过长途运输的牛更有可能接受群体预防性用药治疗。倾向得分匹配法被用于试图估计群体预防性用药治疗对饲养场牛的影响。倾向得分匹配法无法克服数据中存在的内生性问题（内生性源于更有可能从治疗中受益的动物接受了治疗）。该数据集包含牛的体重、购买地以及牛是否来自销售场等信息，因此饲养场的治疗决策肯定是基于未记录且未包含在数据集中的信息。作为一项观察性研究，除了数据限制外还有其他局限性，比如所研究的饲养场可能不具有其他饲养场的代表性。尽管未确定群体预防性用药的效果，但无法确定这一事实支持了关于饲养场确实对最有可能需要群体预防性用药治疗的动物进行了治疗的观点。这应减轻一些对群体预防性用药治疗被过度使用以及抗菌药物被不必要使用的担忧。
