Selecting the desirable method for predicting 305-day lactation yields in Mongolia.

In Mongolia, milk production must be improved both quantitatively and qualitatively, and we must find the most desirable method for predicting 305-day milk yields for cows in Mongolia. Therefore, the predicted 305-day milk yield from the test interval method (TIM), multiple-trait prediction (MTP) and the random regression model (RRM) were compared. The daily milk production records during 305 days for cows calving from 1986 to 2007 from the National Livestock Breeding Center in Japan, and the test day records every month for cows calving from 1985 to 2005 from the Hokkaido Dairy Milk Recording and Testing Association were used. Wilmink's model for the average of lactation curve in MTP was adopted. A cubic Legendre polynomials and the parameters of Wilmink's function were used for RRM. The results suggested that RRM was the most desirable method for predicting 305-day milk yields in Mongolia because estimates by RRM were the most accurate when using over four records. Further analyses will be required to examine the properties of RRM when predicting 305-day milk yields using test day records in Mongolia.