Evaluation of feed additives for increasing wool production from Merino sheep. 1. Lasalocid, avoparcin and flavomycin included in lucerne-based pellets or oaten chaff fed at maintenance

Abstract

Three feed additives were studied for their potential to improve wool growth in sheep fed 2 diets; oaten chaff, or a pelleted mixture (g/kg) of lucerne (590), lupins (250), barley (1 50) and a mineral and vitamin mix (10). Additives were included with each diet as follows (mg/kg feed): avoparcin 25,50,75; flavomycin 5, 15, 30; lasalocid 30, 50, 70. Diets were fed at maintenance to mature Merino wethers for 9 weeks, and measurements were made of wool growth and rumen fermentation characteristics. Animals fed the pelleted diet grew more wool than those fed the chaff diet (6.3 compared with 5.1 g/m2.day, P<0.001), but none of the additives resulted in any significant differences in wool growth compared with the controls. The additives avoparcin and lasalocid increased the ratio of the volatile fatty acids propionate:acetate in animals eating both of the diets (P< 0.001), but flavomycin had no significant effect. Rumen ammonia concentration was increased with avoparcin on both diets (P< 0.001) and with lasalocid and flavomycin on the pelleted diet ( P < 0.05). None of the additives tested significantly influenced liveweight change in comparison with the control groups.