Agroscope, Tänikon 1, 8356 Ettenhausen, Switzerland; University of Geneva, Geneva School of Social Sciences, Boulevard du Pont d' Arve 40, 1211 Geneva, Switzerland.
Agroscope, Tänikon 1, 8356 Ettenhausen, Switzerland.
Res Vet Sci. 2022 Dec 20;152:333-353. doi: 10.1016/j.rvsc.2022.08.021. Epub 2022 Aug 30.
Observational studies are important in livestock science. As treatment is not assigned randomly in such studies, selection bias can be a problem. This is often addressed by matching methods. However, if treatment and control groups differ considerably in their characteristics, it might be necessary to additionally prune observations that lack overlap in the opposite group. "Matching Frontier" method was developed because pruning observations manually often results in suboptimal solutions. The feasibility of the approach for animal health and welfare issues was tested in an observational study evaluating the effect of free stall housing and increased lying comfort on udder health, veterinary costs, and antibiotic usage in Swiss dairy farming. Data were collected in a survey with 1835 Swiss dairy farmers (response rate 28.3%). The treatment group (n = 179) comprised farmers participating in a voluntary animal welfare program that, in addition to free stall housing, required increased lying comfort. Farmers in the control group (n = 229) kept their cows in tie stalls. Using the Matching Frontier method, treated units were matched to control units based on five confounders. Subsequently, observations were pruned to achieve sufficient balance and overlap between the two groups. The effect of the program on the eight outcome variables was finally estimated using linear regression. Farmers in the treatment group had a lower incidence of clinical mastitis (-3.66 per 100 cow-years, -25%, p < 0.05), a lower incidence of culled cows due to udder health problems (-1.61 per 100 cow-years, -30%, p < 0.05), fewer veterinary costs (-42.44 per cow-year, -22%, p < 0.05), a lower incidence of total intramammary antibiotic treatments (-15.88 per 100 cow-years, -23%, p < 0.01), a lower incidence of intramammary antibiotic treatments for mastitis therapy (-7.83 per 100 cow-years, -32%, p < 0.01), and a lower incidence of intramammary antibiotic treatments for dry-cow therapy (-8.80 per 100 cow-years, -21%, p < 0.05). No differences were found for the average somatic cell count and the number of cows with a cell count above 150.000. The results suggest that free stall housing, in combination with increased lying comfort, can have a positive effect on udder health, animal welfare, and the economic situation of the farm. Additionally, fewer antibiotic treatments can be beneficial to public health. The Matching Frontier method has proven to be a helpful tool that may also have added value for future observational studies in livestock science.
观察性研究在畜牧科学中很重要。由于在这类研究中治疗不是随机分配的，选择偏差可能是一个问题。通常通过匹配方法来解决。然而，如果治疗组和对照组在特征上有很大差异，那么可能有必要进一步修剪在对照组中没有重叠的观察值。“匹配前沿”方法是因为手动修剪观察值通常会导致次优的解决方案。该方法的可行性在一项评估自由卧床和增加躺卧舒适度对乳房健康、兽医成本和瑞士奶牛场抗生素使用的影响的观察性研究中进行了测试。数据来自一项对 1835 名瑞士奶农的调查(回应率为 28.3%)。治疗组(n=179)由参加动物福利自愿计划的农民组成，该计划除了自由卧床外，还要求增加躺卧舒适度。对照组(n=229)的农民让他们的奶牛在拴系牛舍中。使用匹配前沿方法，根据五个混杂因素将治疗组的单位与对照组的单位进行匹配。随后，修剪观察值以实现两组之间的充分平衡和重叠。最后，使用线性回归估计该计划对八个结果变量的影响。治疗组的奶牛临床乳腺炎发病率较低(-3.66/100 奶牛年，-25%，p<0.05)，因乳房健康问题淘汰的奶牛发病率较低(-1.61/100 奶牛年，-30%，p<0.05)，兽医费用较低(-42.44/头年，-22%，p<0.05)，总隐性乳房炎抗生素治疗发生率较低(-15.88/100 奶牛年，-23%，p<0.01)，隐性乳房炎抗生素治疗乳腺炎治疗发生率较低(-7.83/100 奶牛年，-32%，p<0.01)，隐性乳房炎抗生素治疗干奶牛治疗发生率较低(-8.80/100 奶牛年，-21%，p<0.05)。体细胞计数平均值和体细胞计数高于 150000 的奶牛数量没有差异。结果表明，自由卧床结合增加躺卧舒适度对乳房健康、动物福利和农场的经济状况有积极影响。此外，减少抗生素治疗可能对公共卫生有益。匹配前沿方法已被证明是一种有用的工具，对未来的畜牧科学观察性研究也可能具有附加价值。
