Analysis of the factors influencing longevity in Holstein-Friesian cows

Background: The resilience, health status, reproduction and milk production as well as the longevity of dairy cows are greatly influenced by the conformation traits. In Hungary, the average number of lactation ranges from 2.1 to 2.2. According to previous studies, the conformation traits are the main effecting factors regarding the longevity. Objectives: The aim of our research was to evaluate the conformation traits of Hungarian Holstein-Friesian herds using survival analysis. The relationship between longevity and main type traits as well as the relationship between longevity and linear type traits was evaluated. Materials and methods: The data of 17 938 cows from four Holstein-Friesian cattle herds were evaluated in our study. At the time of evaluation, 4 089 cows were still in production, and their performance was considered as censored data. The cows born from 2000 to 2017 were analysed. Relationship among the first calving age, herd, conformation traits and longevity were evaluated using survival analysis with Survival Kit. Results and discussion: Based on our results, the first calving age, herd, overall udder score, dairy form, final score, body depth, angularity, rump width, fore udder attachment, udder depth and teat length affected longevity. The highest risk of culling was noticed for cows having calved after 28 months. Cows with higher udder and final scores also had longer productive life, while increases in dairy form scores were associated with shorter life. Cows with intermediate body depth, narrower rump, stronger fore udder, shallower udder and intermediate teats were remained in production for a longer period. The relationship among rump angle, central ligament, front teat placement, rear leg rear view, rear leg side view, and longevity has not been established what was in contradiction with previous studies and practical experiences.