Journal of Animal Science and Veterinary Medicine

This study was designed to determine the risk factors for twinning and its effects on the subsequent production and reproductive performances in Moroccan Holstein cows. The data analyzed were from records of 1770 calving events (157 for twins and 1613 for singles) from July 2008 to December 2012 in a private farm. The logistic regression was used to estimate the effect of risk factors comprising parity, calving season and calving year. To analyze the twinning effect on gestation length, days to the first insemination, days open, the number of insemination per conception, 305-day milk and fat yields and fat percentage, the linear model that included fixed effects of parity, calving season, calving year and calving type was used. Out of 1770 calvings, 157 or 8.87% were twins. Risk factors for twin calvings were parity (p<0.001) and calving season (p<0.05), while calving year had no significant effect (p>0.05). The greatest twinning rate was observed at parity 2 and when calving occurred from May to August. Twin calving affected fat percentage in the lactation initiated by twinning, whereas milk and fat yields were not significantly influenced (p>0.05). Twin-calved cows had a greater fat percentage than single-calved cows (p<0.01). Cows delivering twins had shorter (p<0.001) gestation lengths than those giving singles (273.4 vs. 278.2 days), whereas days to the first insemination, days open and the number of inseminations per conception were not affected by twinning (p>0.05). Therefore, intensive management is required for twin calving cows and their calves to achieve maximum production and to diminish losses