Factors Affecting Birth and Weaning Weights in Korean Indigenous Breed Calves

Background: Understanding the factors that affect calf growth performance can enhance productivity in the cattle industry. This study investigated the effects of breed and sex, the difference between the date of birth and the estimated due date (DBE, gestation length), birth seasons, dam parity and age on body weight at birth and weaning in calves of Korean indigenous cattle breeds. Additionally, the correlation between body weight and body measurements at weaning was assessed. Methods: A total of 246 calves (Hanwoo, n=136; White Hanwoo, n=42; Chikso, n=41; and Heugu, n=27) born between January 2016 and June 2023 were used in this study. All calves were raised with their dams until weaning. Multiple linear regression (MLR) was employed to evaluate the effects of breed, sex, DBE, birth season, dam parity and dam age on birth and weaning weight. Correlation analysis was conducted to assess the relationship between body weight and body measurements at weaning. Result: Breed, sex, DBE and birth season significantly affected both birth and weaning weights (p less than 0.05). Hanwoo calves were the heaviest at birth, followed by Heugu, Chikso and White Hanwoo; at weaning, the order was Hanwoo, White Hanwoo, Chikso and Heugu. Male calves were heavier than females at both stages (p less than 0.05). Calves born after the estimated due date were heavier at birth and weaning (p less than 0.05). Calves born in summer had higher birth weights, while those born in winter had higher weaning weights (p less than 0.05). Dam parity did not affect birth weight (p=0.318) but significantly influenced weaning weight (p=0.028), with higher parity associated with greater weaning weight. Birth weight was a significant predictor of weaning weight (p less than 0.001). Weaning weight showed strong positive correlations with chest girth (r=0.939), body length (r=0.827), withers height (r=0.816), rump height (r=0.814), pelvic width (r=0.788), rump width (r=0.782), chest width (r=0.752) and chest depth (r=0.714).