Abstract

Approximately 53% of 6-month-old dairy heifers in New Zealand do not meet liveweight targets, partially due to inadequate growth rates in their first summer. The aim of this experiment was to determine the effect of feeding forage crops on the growth rate of dairy heifers over this critical period. Sixty six-month-old dairy heifers grazed one of three treatments: pasture, lucerne or a mixed-herb crop for a 63-day period. Both lucerne- and crop-fed heifers had similar (P>0.05) average daily liveweight gain (0.80 ± 0.02 and 0.75 ± 0.02 kg/day, respectively) and were greater (P<0.05) than those of pasture-fed heifers (0.53 ± 0.02 kg/ day). Lucerne-fed heifers had a greater (P<0.05) increase in body length (18.4 ± 1.3 cm) than heifers fed pasture (14.7 ± 1.2 cm). Heifers fed lucerne had higher (P<0.05) concentrations of urea in plasma (4.9 ± 0.1 mmol/L) compared with heifers fed crop (4.1 ± 0.1 mmol/L), which had greater (P<0.05) concentrations of urea in plasma than heifers fed pasture (2.5 ± 0.1 mmol/L). Feeding a mixed-herb crop or lucerne during the summer period resulted in higher growth rates of dairy heifer calves compared with feeding them pasture.

RC, Handcock, RE Hickson, and PJ Back

Proceedings of the New Zealand Society of Animal Production, Volume 75, Dunedin, 132-135, 2015