Abstract

During 1989, two groups of weaner red deer stags (n=18) grazed either perennial ryegrass (PRG) or Moata annual ryegrass (ARG) based pastures from mid-May until the end of November. Within each group, animals (n=6) were either not immunised or immunised against melatonin using Freund's or Dextran adjuvants. Treatment effects upon winter (W) and spring (S) LWG, proportion of animals attaining target liveweight (93kg; 50kg carcass weight by November 30), pasture composition, voluntary DM intake (VFI), anti-melatonin titres and plasma prolactin concentrations were determined. During winter, LWG (165 v 140 g/day; P<0.05) and VFI (1.62 v 1.20 kg DM/day; P<0.001) were greater for animals grazing ARG than PRG pastures, resulting in a greater proportion of deer attaining the target slaughter weight (60 v 41%). Organic matter digestibility and N content were higher (P<0.05) for the ARG than PRG pastures during winter. Maximum anti-melatonin titres of 1:15,215

DM, Leathwick, ND Barlow, and A Vlassoff

Proceedings of the New Zealand Society of Animal Production, Volume 50, , 245-248, 1990