PRODUCTIVE AND REPRODUCTIVE PERFORMANCE OF RUSSIAN BLACK PIED COWS IN THE FIRST THREE LACTATIONS UNDER HOT CLIMATE CONDITIONS IN UZBEKISTAN

Data on 1809 records of productive and reproductive traits in Black Pied cows were studied to determined the performance of these cows under hot-climate conditions in UzbekistanRepublic during the first three lactations and to analyze some genetic and environmental factors affecting these traits.  The random effects studied were sire and dam within sire. The fixed effects were season of calving/birth (winter from October to March and summer from April to September), year of calving (1971 to 1983)/birth (1968 to 1981) and parity (1 to 3).  Data were analyzed using linear mixed model least squares and maximum likelihood (LSMLMW) computer program of Harvey (1990). The overall mean (±S.D) of total milk yield (TMY) was 4056±1112 kg, 305-d milk yield (305-dMY) was 3860±959 kg, fat percentage (FP%) was 3.69±0.16, lactation period (LP) was 307±58.4 days, dry period (DP) was 79.3±37.7 days, fat yield (FY) was 150±40.7 kg, fat-corrected milk was 3865±1051 kg, annualized milk yield was 3861±991 kg, calving interval (CI) was 386±62.9 days, days open (DO) was 103±63.1 days and age at first calving (AFC) was 871±110 days. Sire of the cow (father) had significant effect on all studied traits except on LP, DP and AFC. Year of calving/birth significantly affected all studied traits except on DP and FCM was not significant.  On the other hand, season of calving/birth had insignificant effect on all traits.  Parity had significant effect on all traits except LP and CI did not affect significantly by parity.  First parity cows had significantly lower TMY, 305-dMY, FP, FCM and AMY means than cows with more than parity.  TMY in the 3^rd lactation was significantly higher than that in the 2^nd and 1^st lactation by 11.5 and 28.6%, respectively (4689 vs 4205 and 3645 kg, respectively).  Each of 305dMY, FY, FCM, and AMY followed the same trend of the TMY during the first three lactations.  Therefore, more attention should be given to cows in the first parity in order to improve the productivity of the cows.  Genetic improvement could be also achieved on these traits through sire selection.