Toledo I M, Cattaneo L, Santos J E P, Dahl G E
Department of Animal Sciences, University of Florida, Gainesville, FL 32611.
Department of Animal Science, Food and Nutrition (DIANA), Università Cattolica del Sacro Cuore, Piacenza 29122, Italy.
JDS Commun. 2024 May 31;5(6):674-678. doi: 10.3168/jdsc.2024-0590. eCollection 2024 Nov.
Dairy cow longevity is an important economic trait for producers. In modern dairy farming, longevity of dairy cows is the result of culling decisions, which are determined by several risk factors, including diseases, and reproductive and productive performance. Previous studies have documented that seasonal changes affect health, behavior, and performance of dairy cows throughout their life cycle. Increasing cow comfort by making management adjustments to decrease exposure to high temperatures during the hot months gives farmers the opportunity to decrease culling risk factors and possibly increase cow productive life. In the present study, we obtained the records of primiparous and multiparous Holstein cows from Florida (n = 10,812) and California (n = 8,197) during a 10-yr period (2012-2022). We analyzed the relationship between birth season and longevity (i.e., cows that remained in the herd for 5 or more lactations) in Florida (n = 1,567) and in California (n = 1,669). The number of cows dead, sold, the reasons why they were sold, and their relationship with birth season were also analyzed in the Florida dataset. The hypothesis was that birth in a cool season will increase the length of herd productive life and decrease the number of cows sold or dead during all lactations. The birth seasons were cool (CL; cows born in December, January, February, or March) and hot (HS; cows born in June, July, August, or September). Results showed that in Florida, most cows that remained in the herd for more than 5 lactations (i.e., 14.5% of total cow records) were born during CL compared with cows born during HS (1,129, 72% vs. 438, 28%). The same observations were made in California, where greater longevity (i.e., 5 or more lactations, representing 20.4% of total cow records) was attributed to cows born in CL compared with HS cows (939, 56.3% vs. 730, 43.7%). In Florida, a greater number of HS were sold compared with CL cows (765, 52.6% vs. 689, 47.4%). More HS cows were sold due to breeding, foot and leg, and mastitis issues in Florida. Increased cow death during the first 4 lactations was significantly associated with HS (107, 53.8% vs. 92, 46.2%). Results of this study may help farmers create opportunities to make management adjustments related to birth season, or alter negative seasonal factors (i.e., heat stress) to possibly increase cow longevity in dairy herds.
奶牛的长寿对养殖者来说是一项重要的经济性状。在现代奶牛养殖中，奶牛的长寿是淘汰决策的结果，而淘汰决策由多种风险因素决定，包括疾病、繁殖和生产性能。先前的研究记录表明，季节变化会影响奶牛整个生命周期的健康、行为和生产性能。通过在炎热月份进行管理调整以减少奶牛暴露于高温环境，从而提高奶牛舒适度，这使养殖者有机会降低淘汰风险因素，并有可能延长奶牛的生产寿命。在本研究中，我们获取了2012年至2022年这10年间佛罗里达州（n = 10,812头）和加利福尼亚州（n = 8,197头）初产和经产荷斯坦奶牛的记录。我们分析了佛罗里达州（n = 1,567头）和加利福尼亚州（n = 1,669头）出生季节与长寿（即留在牛群中进行5次或更多次泌乳的奶牛）之间的关系。我们还在佛罗里达州的数据集中分析了死亡、出售奶牛的数量、出售原因以及它们与出生季节的关系。我们的假设是，在凉爽季节出生将增加牛群的生产寿命，并减少所有泌乳期内出售或死亡的奶牛数量。出生季节分为凉爽（CL；12月、1月、2月或3月出生的奶牛）和炎热（HS；6月、7月、8月或9月出生的奶牛）。结果表明，在佛罗里达州，留在牛群中进行5次以上泌乳的大多数奶牛（即占奶牛记录总数的14.
