Effect of non-genetic factors on weekly test day milk yields and first lactation traits in Sahiwal cattle

A total of 577 sahiwal Cattle maintained at National Dairy Research Institute, Karnal were analyzed to study the effect of period, season and age at first calving on first lactation traits. The least squares means for first lactation 305 day, age at first calving and first service period were 1846.55 ± 44.31 kg, 1118.441 ± 5.259 days and 170.14 ± 8.06 days, respectively. Effect of period was highly significant (P≤0.01) and effect of season was non-significant on AFC, FSP and FL305DMY. The maximum (2107.48 ± 176.59 kg) average FL305DMY was observed for sahiwal cattle having with FSP between 331–360 days and minimum (1554.31 ± 67.32 kg) for the sahiwal cattle with 61–90 days. The least squares means of overall weekly test day milk yields ranges from 5.16 ± 0.14 to 7.78 ± 0.17 kg. The effect of periods of calving on all the weekly test day yields was highly significant (P≤0.01). The average weekly test day milk yields were lowest for the heifers calving for the first time at an early age of 900 days or less for all the test day milk yields.