What is the best first-calving age of cows in robotic milking farms?

The aim of this study is to determine the effect of first-calving age (FCA) on yield parameters and productive life in dairy farms using a robotic milking system in Turkey. The cows (n = 1579) were divided into five groups (24, 25, 26, 27, 28 months and above FCA. The average milk yield was highest in 24 months of FCA (9140.31 ± 145.55 kg) and was lowest in 27 months of FCA (8534.55 ± 131.00 kg) (p < .05). The average service period length in the first lactation was longer in cows of 28 months old (158.92 ± 7.28 days) than 26 and 27 months (131.96 ± 4.45and 130.51 ± 54.97 days respectively) old groups (p < .05). A number of lactations of cows that were 26 months old (2.52 ± 0.09) at FCA was higher than those FCA was 24 months and 28 months (2.03 ± 0.15 and 2.18 ± 0.09 respectively) (p < .05). Replacement rates were not differing statistically at different lactations. The most frequent reasons for culling were mastitis and reproduction in all groups. As a result, cows in 24 months of FCA had no undesirable results in terms of milk yield, service period, number of insemination per lactation