A meat production system with Hereford bullocks and two levels of winter supplementation

Claudio Rojas G.1

The system started with 18 Hereford bullocks, 7 to 9 months oid, born in spring, to be soid fat at 14-15 months oid. The average initial weight was 168.5 kg/head. Qn May 1, all the animais were put to graze on a dryland seeded pasture, composed mainiy of Trifolium repens, Lollum multiflorum, and L. perenne. On June 16, two groups were formed and fed, in an open forest, silage at libitum plus 1.5 kg/head (T1) or 2.5 kg/head (T2) concentrate. On September 28, both groups were put to graze in the same pasture, until they were soid fat on December 10, Centesimal yield (cold and warm), lenght, dorsal muscle area, and fat thickness were measured in the carcass. During the initia) grazing period (autumn), average liveweight gain was 0.44 kg/head, During winter suppiementation, T2 bul)ocks gained (1.04 kg/day) significantly (P < 001) more than Ti builocks (0.65 kg/day). During the following grazing period (spring), gains were similar (T1 = 1.2 and T2 = 1.0 kg/day; P > 0.05). Final liveweights, at 15 months oid, were 344,3 and 370,7 kg/head; average daily gains for the entire cycle were 0.79 and 0.91 kg/head; and productions/ha were 711 and 762 kg uveweight; ah for T1 and T2, respectiveiy. Both groups were sold together, and there was no discrimination in prices; also, carcass measurements did fol show any significant differences.

1 Estación Experimental Carillanca (INIA), Casilla 58-D, Temuco, Chile.