Listy Biometryczne - Biometrical Letters, Vol. 40 (2003), No. 2, 73-80

The accuracy of 200-day milk yield estimation in cows, obtained on the basis of 4 test yields taken in the first 100 days of lactation, was compared with the accuracy achieved when the 4 yields were recorded during the whole 200-day period. In the study, daily milk yields in a herd of 156 cows were used. Relative estimation error (with regard to the real yields of appropriate cows), mean estimation error and error variance were computed for 100 and 200 days of lactation. Mean error values of 200-day milk yield estimation by test yields from the 100-day period were comparable to the values obtained when the yields were taken during the 200-day period. The error variance turned out to be even slightly smaller for the 200-day yield estimation based on the 100-day period. This suggests that the method presented might be used to predict longer period yields with data from shorter ones.

lactation curve, milk yield.