Effects of herd management practices on somatic cell counts in an arid climate

The objective of this study was to evaluate associations between average lactation somatic cell counts (SCC) and herd management practices in an arid climate. A total of 38,530 average lactation SCC records for 10,216 Holstein cows gathered on 25 dairy farms from January 2009 to October 2012 in Isfahan (Iran) were analyzed. Average lactation SCC (cells × 1,000) was 250.79 ranging from 90.31 to 483.23 cells/mL across investigated farms. Herd-level management factors associated with average lactation SCC were determined separately using mixed linear models in the MIXED procedure with average lactation somatic cell score (SCS) included as the dependent variable. Some of the management practices associated with low average lactation SCS included sawdust combined with sand bedding, using automatic cup removers, disinfection of the teats by dipping into disinfectant, using washable towels for teat cleaning, free-stall barns, wet disposable tissue for udder washing, wearing gloves during milking and the use of humidifiers and shade. Lower-production herds and larger-size herds had lower average lactation somatic cell counts. Most herd management practices associated with average lactation SCC in dairy herds in the arid region of Isfahan are in agreement with most previous studies. However, different results are found for use of humidifier, bedding materials and herd size.

本研究旨在评估干旱气候下奶牛平均泌乳体细胞计数（Somatic Cell Counts, SCC）与牧场管理措施之间的关联。2009年1月至2012年10月间，研究团队从伊朗伊斯法罕的25座奶牛场收集了10216头荷斯坦奶牛的共计38530条平均泌乳体细胞计数记录，用于本次分析。本次调研覆盖的各牧场中，平均泌乳体细胞计数（以细胞数×1000计）的均值为250.79细胞/mL，波动区间为90.31至483.23细胞/mL。随后，以平均泌乳体细胞评分（Somatic Cell Score, SCS）作为因变量，通过MIXED过程中的混合线性模型，分别确定了与平均泌乳体细胞计数相关的牧场级管理因素。与较低平均泌乳体细胞评分相关的部分管理措施包括：以木屑混合沙子作为牛床垫料、使用自动脱杯器、采用乳头药浴消毒方式、使用可清洗毛巾清洁乳头、采用散栏式牛舍、使用一次性湿纸巾清洗乳房、挤奶时佩戴手套，以及配备加湿器和遮阳设施。研究发现，低产牛群与大规模牛群的平均泌乳体细胞计数更低。本研究中，与伊斯法罕干旱地区奶牛场平均泌乳体细胞计数相关的多数牧场管理措施，与既往多数研究结果保持一致。但在加湿器使用、垫料材质选择以及牛群规模这几个维度上，本研究得出了与前人不同的结论。