Production performance of crossbred dairy cow in Kurdistan province under village conditions

This study was carried out in Kurdistan Province in the western part of Iran, to identify the influence of genetic and non-genetic factors on reproductive performance of Kurdi and their crossbred cows with specific gene content under rural smallholder management condition. Reproduction data of 87 Kurdi cows from 29 random herds for a calving interval during 2007-2008 and 777 crossbred cows (970 records) from 210 random herds along two calving periods (1998-2001 and 2004-2007) were collected. Derived traits of interest were age at first calving (AFC), days open (DO), gestation length (GL) and calving interval (CI).General Linear Model's procedure of SPSS software was used to analyse the data. Primary model to analyze DO, GL and CI was covariance model with fixed effects of sire breed, exotic gene percentage, region, calving period, season and parity number and AFC as covariate. Primary model to analyze AFC was variance model with fixed effects of sire breed, exotic gene percentage, region and calving period. The means of AFC, DO, GL and CI were 33 months and 92, 272 and 364 days for Kurdi cows, they were 28 months and 113, 277 and 390 days for crossbred cows, respectively. In comparison with Kurdi cows, AFC decreased and other traits increased in crosses. In crossbred cows, the correlation coefficient between DO and CI was highly significant (r = 0.989), and AFC had no significant effect on DO, GL and CI. In contrast to sire breed, exotic gene percentage significantly (p0.01) influenced all traits. Increase of exotic gene percentage resulted in decreasing AFC and increasing DO, GL and CI. Crossbred cows with ≥75% exotic gene had significantly (p0.01) less AFC and more DO and CI than other groups. Different regions had no effect on DO, GL and CI, but AFC was significantly (p0.01) higher in plain region than mountainous region .All traits were tested and no significant difference was found for calving periods. Season of calving significantly influenced next DO (p0.05) and GL (p0.01). CI was not significantly affected, while its pattern of changes was consistent with DO. The maximum and minimum intervals of DO were belonging to the summer and winter, respectively. Parity number had significant (p0.01) effect on next DO, GL and CI. The lowest DO and CI were related to ≥4 parity group. It could be concluded that the main concern in view of reproductive performance in crossbred cows is related to CI. DO and CI have relatively desirable values in 75% crosses, however ≥75% crossbred cows have unacceptable means for these traits. If the aim is upgrading to ≥75%, the necessary management practices (housing, nutrition and reproduction) to reduce postpartum anoestrus and service periods must be performed. Moreover, to determine more effective factors on days open some more research must be conducted.