Department of Animal Science, College of Agriculture, Isfahan University of Technology, Isfahan, Iran.
Department of Animal Science, Faculty of Agriculture, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran.
Vet Med Sci. 2024 Nov;10(6):e70107. doi: 10.1002/vms3.70107.
Voluntary waiting period (VWP), housing systems and the presence of a veterinarian are effective factors on reproductive performance of a dairy farm.
This study aimed to investigate the management practices associated with VWP and its effects on reproductive performance.
A total of 136,943 records of 21,756 cows that calved between 1990 and 2013 were used. A questionnaire was also conducted with the farms involved to determine if they adjust the timing of insemination based on the body condition score (BCS) of the cows, postpartum health situation (PPHS) or environmental factors such as heat stress and season. The impact of changing the VWP selectively, the presence of a veterinarian and the type of barn on reproductive outcomes like days open (DO), number of services per conception (NSPC) and days to first service (DFS) was examined using a linear mixed model. This model considered animals and herds as random factors and management practices as fixed factors in the analysis.
Among herds that reported altering the VWP based on heat stress, DFS significantly increased (61.68 ± 0.68 vs. 58.4 ± 0.83) while DO (119.70 ± 1.86 vs. 126.9 ± 2.29) and NSPC (1.98 ± 0.04 vs. 2.48 ± 0.05) reduced compared to herds that did not alter the VWP. Our results showed that farms with a full-time veterinarian had a better reproductive performance than those with part-time care (p < 0.05). Housing system was significantly associated with fertility traits, so that cows in free-stall barns were more fertile than those kept in open-shed barns.
The obtained results from this study indicated that management decisions to selectively altering the VWP led to difference in DFS and improved reproductive performance.
自愿等待期（VWP）、住房系统和兽医的存在是影响奶牛场繁殖性能的有效因素。
本研究旨在调查与 VWP 相关的管理实践及其对繁殖性能的影响。
共使用了 1990 年至 2013 年间 21756 头奶牛的 136943 条记录。还对参与的农场进行了问卷调查，以确定它们是否根据奶牛的身体状况评分（BCS）、产后健康状况（PPHS）或热应激和季节等环境因素来调整授精时间。使用线性混合模型检查选择性改变 VWP、兽医的存在和畜舍类型对开放天数（DO）、受孕所需服务次数（NSPC）和首次服务天数（DFS）等繁殖结果的影响。该模型在分析中考虑了动物和畜群作为随机因素，以及管理实践作为固定因素。
在报告根据热应激改变 VWP 的畜群中，DFS 显著增加（61.68 ± 0.68 比 58.4 ± 0.83），而 DO（119.70 ± 1.86 比 126.9 ± 2.29）和 NSPC（1.98 ± 0.04 比 2.48 ± 0.05）减少。与不改变 VWP 的畜群相比，我们的结果表明，拥有全职兽医的农场比兼职兽医的农场具有更好的繁殖性能（p < 0.05）。畜舍系统与繁殖性能显著相关，因此，自由卧床畜舍的奶牛比开放式畜舍的奶牛更具繁殖力。
本研究的结果表明，选择性改变 VWP 的管理决策导致 DFS 差异和繁殖性能提高。
