Use of bootstrapped, regularised regression to identify factors associated with lamb-derived revenue on commercial sheep farms
Use of bootstrapped, regularised regression to identify factors associated with lamb-derived revenue on commercial sheep farms
复制标题
DOI：
10.1016/j.prevetmed.2019.104851
复制
发表时间：
2020-01-01
影响因子：
2.6
通讯作者：
Kaler, Jasmeet
中科院分区：
文献类型：
--
作者：
Lima, Eliana;Green, Martin;Kaler, Jasmeet
英国养羊场的盈利能力参差不齐，许多养羊场出现净亏损。为了经济的可持续性，农场必须盈利，因此在控制成本的同时最大限度地提高收入非常重要。羊群最重要的收入来源是羊肉生产，但很少有信息解释农场之间羊肉销售收入的差异。这项研究的目的是确定农场，农民和管理因素可能有最大的，最可靠的协会与畜牧业收入。从人口的830个羊场，408农民完成了在线问卷调查，其中包括300多个变量。使用屠宰场资料（包括屠体分类）计算各农场的总屠宰收益。羊群规模中位数为560只母羊，土地面积中位数为265英亩，每英亩出售羔羊的收入中位数为197磅（IQR = 120-296），每只母羊的收入中位数为95磅（IQR = 72-123）。使用正则化（弹性网络）回归与自举的稳健分析方法，以解释数据中的多重共线性，并降低模型过度拟合的可能性。为了提供模型推断并允许变量根据相关性进行排序，对协变量稳定性和系数分布进行了评估。（中位效应大小（）磅95%自举概率区间）;放牧率增加0.2母羊/英亩（13; 6-17），肥料被用于大部分牧场（18; 0.1-37）、利用轮牧（13; 0.3-34），脱垂母羊比例降低（4; 0.3-9），分离跛脚羊从其余的羊群（16; 0.9-37），根据脱垂选择母羊进行淘汰（20; 0.2-55）和不孕症（20; 2-46）、产羔时对母羊进行体况评分（28; 3-58）、早期哺乳期（21; 1-54）或断奶期（25; 2-70）、农民教育程度提高（20; 2-54）和农民具有积极的商业态度（15; 0.2-38）。其他因素具有较高的稳定性和相对较大的关联性，增加每母羊的收入;从不修剪跛脚母羊的病足（9; 0.8-22）和利用农场记录（5; 0.3-12）。这是动物健康流行病学的第一项研究，使用自举正则化回归来评估一个广泛的数据集，以提供解释协变量的重要性排名。我们的结论是，相对较小的一组变量确定，与潜在的大的影响，衍生收入，应被视为未来的干预研究的主要候选人。
The profitability of UK sheep farms is variable with many farms making a net loss. For economic sustainability, farms have to be profitable, therefore it is important to maximise income whilst controlling costs. The most important source of income in sheep flocks is from lamb production but there is little information on factors that explain variability between farms in revenue from lamb sales. The aim of this research was to identify farm, farmer and management factors likely to have the largest, most reliable associations with lamb-derived revenue.From a population of 830 sheep farms, 408 farmers completed an online questionnaire comprising over 300 variables. Total lamb-derived revenue was calculated for each farm using abattoir information including carcass classification. The median flock size was 560 ewes, median land size 265 acres, median revenue per acre from lambs sold was 197 pound (IQR = 120-296) and median revenue per ewe 95 pound (IQR = 72-123). A robust analytic approach using regularised (elastic net) regression with bootstrapping was implemented to account for multicollinearity in the data and to reduce the likelihood of model over-fitting. To provide model inference and allow ranking of variables in terms of relevance, covariate stability and coefficient distributions were evaluated.Factors with high stability and relatively large positive associations with revenue per acre were (median effect size (); pound 95 % bootstrap probability interval); an increased stocking rate of 0.2 ewe/acre (13; 6-17), fertilizer being used on most of the grazing land (18; 0.1-37), the use of rotational grazing (13; 0.3-34), decreased proportion of ewes with prolapses (4; 0.3-9), separation of lame sheep from the rest of the flock (16; 0.9-37), selecting ewes for culling based on prolapses (20; 0.2-55) and infertility (20; 2-46), conducting body condition scoring of ewes at lambing (28; 3-58), early lactation (21; 1-54) or weaning (25; 2-70), increased farmer education (20; 2-54) and farmers with a positive business attitude (15; 0.2-38). Additional factors with a high stability and relatively large associations with increased revenue per ewe were; never trimming diseased feet of lame ewes (9; 0.8-22) and making use of farm records (5; 0.3-12).This is the first study in animal health epidemiology to use bootstrapped regularised regression to evaluate a wide dataset to provide a ranking of the importance of explanatory covariates. We conclude that the relatively small set of variables identified, with a potentially large influence on lamb-derived revenue, should be considered prime candidates for future intervention studies.