Growth rates of dairy heifers fed alternative feeds

摘要

Dairy heifers need to achieve average daily gains (ADG) that allow them to reach live weight targets. The aim of this experiment was to measure the effects of grazing 6-month-old dairy heifers on alternative feeds, over the summer period. Sixty 6-month-old Friesian-Jersey crossbred heifers were assigned to one of three treatments (pasture (P), conserved forages (C) or lucerne (L), with all treatments receiving supplementary meal. For the 6-week experiment, feed allowance was based on liveweight gainrequired to meet liveweight targets. Heifers were weighed at 0, 3 and 6 weeks of the treatment period. Wither height, crown-to-rump length and girth circumference were measured at the start and end of the experiment. L heifers had a greater (P<0.05) average daily gain (1.22 + 0.03 kg/day) than P heifers (0.57 + 0.03 kg/day), and C heifers were intermediate (0.78 + 0.03 kg/day). L and C heifers had a greater (PO.01) increase in wither height (0.15 + 0.01 cm/day and 0.14 + 0.01 cm/day respectively) than Pheifers (0.11 + 0.01 cm/day). L heifers had the greatest (P<0.05) increase in girth circumference (0.30 + 0.02 cm/day, compared with P and C heifers: 0.22 + 0.02 cm/day and 0.16 + 0.02 cm/day respectively). A combined diet of lucerne and meal during drought conditions increased ADG resulting in a greater proportion of heifers reaching liveweight targets.