The cost of being early or late: Biological and economic outcomes of age at first calving in dairy buffaloes

Age at first calving (AFC) is a key determinant of lifetime productivity and profitability in dairy herds, yet its long-term effects in dairy buffaloes remain poorly documented. This study evaluated the influence of AFC on milk yield and composition, reproductive performance, and economic outcomes in Italian Mediterranean buffaloes reared under commercial conditions. Data included 576,028 test-day records from 27,744 buffaloes across 110 herds, collected over a 10-yr period (2013-2023). Animals were grouped into 8 AFC classes and stratified by parity order, namely: primiparous, mid-parity (second-third parities), and greater parity (≥4). Productive traits comprised daily milk yield, fat and protein content, SCS, and cumulative yields of milk, fat, and protein per lactation, whereas reproductive traits included calving interval (CIN) and days open (DO). Mixed-model analysis indicated that mid- and greater-parity buffaloes calving between 35 and 38 mo achieved higher daily milk yield, whereas daily milk yield increased progressively with AFC in primiparous buffaloes. Milk fat content was unaffected by AFC, whereas the highest protein percentages were observed in mid-parity buffaloes calving at AFC between 32 and 34 mo. Somatic cell score significantly decreased as AFC increased across all parity groups, except in primiparous buffaloes, where an increase in SCS was observed in buffaloes with AFC between 37 and 38 mo. Moreover, CIN and DO were shortest in buffaloes calving the first time between 32 and 37 mo. The economic analysis integrated model-based estimates of milk yield with farm-level cost data from the Farm Accountancy Data Network covering the same 10-yr period. Production costs were organized into 3 categories: direct costs, overheads, and imputed costs. Based on this structure, the average production cost was estimated at €1.38/L of milk. Total production costs per lactation were calculated as the unit cost multiplied by the estimated cumulative milk yield for each AFC class and parity group. Revenues were obtained in the same way, by applying the actual farm-gate milk price (€1.50/L) to the estimated cumulative milk yields, providing a standardized framework for comparison across AFC classes. Net profit was calculated as the difference between total revenues and production costs, yielding an overall average of €314 per lactation across all AFC and parity groups. The highest net profit was recorded in mid-parity buffaloes whose first calving occurred between 37 and 38 mo of age, with an average net return of €339 per lactation. Overall, buffaloes calving the first time between 34 and 42 mo achieved significantly higher net profit compared with other AFC classes. Conversely, both early (<30 mo) and late (>42 mo) AFC values were associated with reduced net profits, driven by lower milk yields. Overall, these results indicate that targeting an AFC of 35 to 38 mo provides the most favorable balance between biological performance, udder health, reproductive efficiency, and farm profitability.