Reproductive performance of crossbred dairy cows under smallholder production system in Kurdistan province of Iran

Abstract

The sustainability and improving of milk production and the profitability of smallholder dairy units require integrated assessment of reproductive performance. The purpose of this study is to identify reproductive performance, and genetic and non-genetic factors affecting the performance of Kurdi crosses with Holstein and Brown Swiss, developed in recent years, under rural smallholder management. The cross breeding data were related to 210 herds, 885 cows and 970 calving intervals from two calving periods of 1998–2001 and 2004–2007. The traits of interest were age at first calving (AFC), days open (DO), gestation length (GL) and calving interval (CI). The means of AFC, DO, GL and CI were 28 months and 113, 277 and 390 days for crossbreds. In contrast to the sire breed, exotic gene percentage significantly influenced all traits (p < 0.01). DO, GL and CI were tested and no significant differences were found for the regions and calving periods. Season of calving significantly influenced next DO (p < 0.05) and GL (p < 0.01). Parity number had significant effect on next DO, GL and CI (p < 0.01). DO and CI have relatively desirable values in <75% crosses; on the contrary, ≥75% crossbreds have unacceptable means for these traits. For upgrading to ≥75%, the appropriate management practices (housing, nutrition and reproduction) must be considered to reduce postpartum anoestrus and service periods. Moreover, some research to determine more effective factors on DO must be conducted.