Liveweight gain and urinary nitrogen excretion of dairy heifers grazing perennial ryegrass-white clover pasture, canola, and wheat

Abstract

This study was carried out to examine liveweight gain (LWG), urinary nitrogen (N) concentration, and urinary N excretion of dairy heifers grazing perennial ryegrass-white clover pasture, dual-purpose wheat and dual-purpose canola. A temporal replicate design with two replicates was used to conduct the study. A total of 24-30 Friesian × Jersey heifers, aged 9-11 months were allocated into three dietary treatment groups (pasture, canola, and wheat) according to their initial LW (184 ± 7.0 kg; mean ± s.d.) and breeding worth (NZ$142 ± 11.3; mean ± s.d.). Feed was allocated every 4 days with allowance calculated according to feed requirement for maintenance plus 0.8 kg LWG/day. The LWG over ..