Genetic Studies on First Lactation Traits and Life Time Milk Yield in Crossbred Cattle

Abstract

Aims: To study the genetics on first lactation traits and life time milk yield in crossbred cattle. Place and Duration of Study: Instructional Dairy Farm, G B Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India, Between March 2021 and April, 2022. Methodology: Data for this study were collected from the history sheets of crossbred cattle at the instructional dairy farm. The dataset included 976 crossbred cattle from 66 sires over 32 years (1988–2019). Cows with abnormal or incomplete records were excluded. Results: The overall least squares mean of first lactation traits viz. age at first calving (AFC), first service period (FSP), first calving interval (FCI), first dry period (FDP), first lactation length (FLL), first lactation milk yield (FLMY) and lifetime milk yield (LTMY) were estimated to be 1153.20± 2.06 days, 192.95±4.90 days, 468.90±5.11days,129.50± 4.38 days, 339.41± 3.64 days,3376.36±50.40 kg and 14930.60±167.65kg, respectively. Season of calving did not significantly affect most traits except age at first calving. Period of calving significantly influenced all traits except first lactation milk yield and lifetime milk yield. Heritability estimates were low, with genetic and phenotypic correlations ranging from very low to high. Variations were mainly due to non-additive genetic variance, suggesting improvements can be achieved through better management and feeding practices. Conclusion: Therefore, it can be concluded that there is limited scope for selecting cows based on lifetime traits. It is more advantageous to focus on selecting animals based on their performance in earlier lactation traits rather than traits that are expressed later in life.