Comparison of Influencing Factors on Birth Weight between Holstein and Jersey Calves

The birth weight of calves indicates livestock production performance even before birth, significantly impacting calf health and overall farm productivity. This study was conducted on the factors influencing the birth weight of Holstein and Jersey calves born under the same environmental and feeding conditions. Data were collected during 2016–2024 on 635 cows (Holstein, n = 572; Jersey, n = 63) and their calves, including details such as breed, age and parity of the dam, difference between the date of birth and estimated due date (DBE), birth season, sex and birth weight. The calving season was categorized into spring (March-May), summer (June-August), autumn (September-November) andwinter (December-February). Stepwise multiple regression analyses were conducted to determine the impact of these variables on the birth weight of calves. In Holstein calves, DBE (β = 0.350) had the most substantial impact, followed by sex (β = 0.316), age of dam (β = 0.083) andbirth during autumn (β = -0.112) (p<0.05). For Jersey calves, DBE (β = 0.448) was the most significant factor, followed by sex (β = 0.277) and age of dam (β = 0.228). Unlike Holsteins, no seasonal effect was observed in Jerseys. These findings highlight the influence of various factors on birth weight of calves, suggesting that Jersey cattle may possess certain advantages in seasonal birth conditions compared to those of holstein cattle.