Frequency of recording for selection on milk production

Abstract

Five milk recording methods were compared: three methods with register of the production of two milkings with biweekly (BW), monthly (M) and bimonthly (BM) frequency; and two methods (A &C) with register of only one milking, alternating the morning and afternoon milkings monthly. The daily production records of 509 lactations of HPB, Jersey and mixed HPB-Gir cows were used. For 425 lactations of 176 cows, it was possible to correct the total production by age and blood degree, and to express it as a deviation from the contemporary companions. For effects of selection on milk production, all the methods studied resulted in a similar genetic gain, for cows as well as for bulls, enabling the choice between them to be made solely on the basis of practical considerations.