PERFORMANCE OF HEREFORD × SHORTHORN BULLS AND STEERS RAISED IN NORTHERN ONTARIO AND FED DIFFERENT LEVELS OF GRASS SILAGE AND HIGH MOISTURE BARLEY

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Abstract
Over a 2-yr period, 44 bulls and 44 implanted steers of Hereford × Shorthorn breeding were fed, from weaning to slaughter, diets of grass silage with 0, 0.45, 0.9 or 1.35 kg barley dry matter (DM)/100 kg liveweight. Each animal was slaughtered when it had 8 mm of fat over the loin as determined by ultrasound measurement. As the level of barley in the diet increased the rate of gain increased (P < 0.01), as did DM intake (P < 0.05) while feed required per kilogram gained and days on feed decreased. Bulls and steers responded in a similar manner to the different diets. Bulls gained faster (P < 0.01) on similar intakes of DM with the result that feed required for kilogram gain was less for bulls (P < 0.05). There was no difference (P > 0.05) in days to market for bulls and steers. There was no consistent effect of diet on carcass characteristics. However, castration resulted in lighter (P < 0.01) slaughter and carcass weights as well as a smaller (P < 0.01) rib eye area. Key words: Cattle, castration, diet, growth, carcass