Phenotypic and genetic analysis of milking temperament and its correlation with milk production traits in South African Holstein cattle.

Milking temperament (MT) is a crucial trait in dairy production; it affects farm profitability as well as animal and human welfare. Furthermore, poor temperament may increase herd costs by compromising the state and durability of the milking system. There is, however, limited knowledge and recording of MT in South African dairy cattle. The purpose of this study was to evaluate factors influencing MT scores and to estimate genetic parameters among MT and milk production traits (milk yield, fat and protein) in South African Holsteins. Data comprised of MT assessments on 2,844 cows from 16 herds collected between September 2020 and November 2021. Non-genetic effects were analysed by general linear models (GLM) procedure, and repeatability of MT scores was estimated using the variance components procedure of the Statistical Analysis Software. Linear animal models were fitted to estimate genetic parameters, using the ASReml software. Herd-test-day and age of cow at calving (p < 0.0001), and lactation stage (p < 0.05), significantly influenced MT. Repeatability estimate was moderate (0.47 ± 0.03), and the heritability estimate was low (0.05 ± 0.04). Heritability estimates were low to moderate for milk yield and composition, varying from 0.11 ± 0.05 for milk yield to 0.24 ± 0.06 for protein percent (%). Genetic correlation for MT with milk yield was moderate (0.60 ± 0.35). Low correlations were observed for MT with fat % (-0.12 ± 0.24) and protein % (-0.30 ± 0.32). There was no discernible genetic trend for MT in animals born from 2009 to 2019, although there was a minimal overall decline over the period. These findings suggest that there was reasonable consistency in the assessment of MT, and that MT may be improved through selection, using multi-trait models including milk yield.