Effects of region, Holstein Friesian inheritance level, parity, body condition score, and age at first service on productive and reproductive performance of Holstein Friesian crossbred dairy cows in Bangladesh

This study evaluated the associations of region, Holstein Friesian (HF) inheritance level, parity, Body Condition Score (BCS), and Age at First Service (AFS) with the productive and reproductive performance of Holstein Friesian local crossbred (HFLC) cows in Bangladesh. Data were collected from 158 lactating HFLC cows across Gaibandha, Dhaka Metropolitan City, and Mymensingh from January 2021 to January 2022. Productive traits included Average Daily Milk Yield (ADMY) and Lactation Length (LL), while reproductive traits included Service Per Conception (SPC) and Calving Interval (CI). Region significantly influenced CI, ADMY, and LL, with urban farms in Dhaka producing more milk and experiencing longer lactations, while rural farms in Gaibandha had shorter CI. HF inheritance level significantly influenced all productive and reproductive traits. Cows with 50-<62.5% and ≥ 62.5-<75% HF inheritance level had lower SPC and shorter CI, whereas cows with > 75% HF inheritance level showed higher ADMY and longer LL. Parity did not influence CI, ADMY, or LL but significantly influenced SPC, with the lowest SPC observed in first-parity cows. BCS was associated with SPC and LL but not with CI or ADMY. Cows with moderate BCS exhibited lower SPC, while those with higher BCS had longer LL. AFS significantly influenced SPC, CI, and ADMY, emphasizing the importance of first breeding age on reproductive and productive outcomes. Overall, higher HF inheritance levels were linked to increased milk production but reduced reproductive efficiency, whereas moderate HF inheritance levels were associated with better reproductive performance under field conditions in Bangladesh.