Abstract

Production and efficiency of Holstein-Friesian (F), Jersey (J) and crossbred FxJ milked once-a-day (OAD) were studied at Massey University dairy farm No. 1. Herd test records of milk yields, somatic cell score (SCS), live weight (LW) and body condition score (BCS) were used to model the lactation curves using a third-order orthogonal polynomial. Total lactation yields of milk (MY), fat (FY), protein (PY) and milk solids (MS=FY+PY) were calculated based on predicted daily yields. Predicted efficiencies were feed conversion efficiency (FCE; total lactation MS per kg of predicted total lactation dry matter intake [DMI]); biological efficiency (BE; total lactation MS per 100kg of LW) and DMI capacity (DMIC; total lactation DMI per 100kg of LW). Holstein-Friesian cows yielded 376kg milk more than FxJ cows and 1101kg milk more than J cows per lactation. Holstein-Friesian and FxJ produced similar total lactation MSY (366 and 369kg, respectively). Jersey cows were more efficient than cows of the other breeds: FCE was 78.2, 82.3 and 86.3; BE was 69.7, 74.1 and 77.8; and DMIC was 887.9, 896.8 and 897.7 for F, FxJ and J cows, respectively. There were significant differences in production and efficiency among the breeds, with J cows being more efficient per 100kg of LW than F or FxJ cows. Further research is required to compare breed profit per ha in order to conclude the best breed for OAD systems.