How the herd trials were organised
IN autumn 1994 two genetic groups (table 1) of in-calf heifers were assembled at Curtins Farm.
Control heifers (C) composed Moorepark stock mainly Dutch crosses of their own breeding. The high genetic merit stock (S) were imported from Holland and France.
In all, 96 spring-calving animals were allocated to the trial and then 16 heifers to each treatment.
Heifers went on their respective feeding systems from early April until the end of lactation.
"The grazing season lasted from early March until early December, when all animals were housed," he said. High and average merit cows in each feeding system were grazed separately in split paddocks. Both the low input and the high concentrate systems followed convention- al grass management. The high grass system saw some modifications.
"Grass production in 1995 was erratic, with poor grass growth in August/September due to drought, so concentrate feeding was higher than planned," claimed Dr Dillon.
Feeding rates were 863kg, 1449kg and 851kg concentrates a cow for the Moorepark, high concentrate and high grass feeding systems, respectively.
Over 200kg of this concentrate was fed during the drought, he said. An extra 1.5t a cow of silage was also fed at this time. *
Table 1: Comparison of genetic index