Abstract

Eight herds each of 24 Friesian cows were stocked at 3.7 cows/ha on separate farmlets during 1982-83 and 1983-84. Annual production per5 hectare averaged 710 kg fat, 537 kg protein, 740 kg lactose and 16.7 t solids corrected milk (SCM). Annual DM intake was 15.8 t/ha and live weight (LW) during lactation, 1487 kg/ha. In a contemporary farmlet trial at an adjoining dairy, 4 purebred Jersey herds each of 15 cows were stocked at 2.8, 3.3, 3.8 and 4.3 cows/ha. Regression analysis was used to derive estimates of the performance of the Jerseys at the same stocking rate, and at a stocking rate that resulted in the same LW/ha, as the Friesians. At a common stocking rate of 3.7 cows/ha, the Friesians were estimated to produce 7, 15, and 13% more fat, protein, and SCM/ha than the Jerseys. Annual conversion efficiency (g milk constituent/kg DM) of the Friesians was estimated to be 10% higher for fat and 18% higher for milk solids than the Jerseys. At the same LW/ha, requiring a Jersey stocking rate of 4.21 cows/ha, the Friesians were estimated to outproduce the Jerseys by 3, 13 and 10% for fat, protein and SCM/ha respectively. Annual conversion efficiency for the Friesians was estimated to be 15 and 25% higher for fat and milk solids respectively than for the Jerseys. For Jerseys, estimated maximum yields per hectare of milkfat and milk solids were at 4.45 and 4.37 cows/ha and were 686 kg fat/ha and 1761 kg milk solids/ha; 4 and 13% respectively less than produced by the Friesians stocked at 3.7 cows/ha. The superior production of the Friesians was due to their higher food conversion efficiency, not to the higher food intake.

AM, Nicol, and AC Parratt

Proceedings of the New Zealand Society of Animal Production, Volume 44, , 253-256, 1984