comparative study between Shami and Holstein cows for longevity and productive lifetime traits under subtropical conditions

This study aimed to compare the longevity and productive lifetime traits between Shami and Hol-stein cows under subtropical conditions, in addition to assess the effect of age at first calving (AFC), first lactation milk yield (FLMY), year and season of first calving on the studied traits in both breeds. The available data included 495 records for Shami and 1129 records for Holstein from birth to disposal date during the period from 1982 to 2014.The studied traits were lifespan (LS), productive life (PL), cow efficiency index (CEI), number of calvings (NC), lifetime milk production (LMP), total lactation periods (TLP), lifetime daily milk production (LDMP), and total dry periods (TDP). The least squares means of LS, PL, CEI and NC were 96.3±1.80 months, 73.2±2.80 months, 64.9±0.008 % and 4.3±0.12 calving for Shami cows in respective order. The corresponding figures for Holstein cows were 66.1±1.81 months, 43.5±2.81 months, 56.4±0.012 % and 3.5±0.19 calving, respectively. The means of LMP, TLP, LDMP and TDP were 7713±563.38 kg, 787±33.43 days, 2.7±0.13 kg and 890±25.55 days for Shami cows and 14406±875.77 kg, 1049±51.96 days, 5.9±0.20 kg and 275±39.72 days for Hol-stein, respectively.The effect of breed was highly significant (P<0.01) on all studied traits. Cows for both breeds with AFC less than 24 months had more PL and NC. Also, cows with the highest average FLMY had the highest LMP, LDMP and TLP. It could be concluded that under the subtropical condi-tions, Shami cows exhibit superiority for longevity traits compared to Holstein ones.