Milk Production of Adapted Saudi Holstein Cows in Relation to Body Condition Scores across Different Stages of Lactation

摘要

Milk yield from adapted cows is facing problems due to varying climatic conditions and adaptability of imported animals. The main objective of study was to describe the relationships between body condition scores and daily milk yield across differentdays in milk. Genetic (co) variances between Body Condition Score (BCS) and test-day milk yield were estimated using a random regression animal model extended to multivariate analysis. A cubic random regression was sufficient to model the changing genetic variances for BCS and milk across different Days in Milk (DIM). The milk yield data was obtained from the electronic herd records. The animal groups (milking cows) were evaluated according to the milk yield level and body condition scores. The additive genetic correlations between BCS and milk production showed high change over the lactation duration (pooled or separate parties). The highest additive correlations between BCS and were around 0.6 across 80-125 days in milk. Body condition scores duringearly and late part of lactation were negative and low related to milk production. This suggests that the highest genetic improvement in daily production from indirect selection on BCS should be based on measurements taken during the mid-lactation stagewhen the additive genetic variance for BCS is the largest.