Abstract

Forty-five crossbred steers weighing 540-580 kg were assigned to three treatment groups. Group 1 received pasture only for 58 days; Group 2 grazed at a similar herbage mass to Group 1 and were supplemented with 4 kg/hd/day of a concentrate ration; Group 3 were on a feedlot and fed 8 kg/hd/day of concentrate together with 2.0 kg/hd/day of straw. Groups 2 and 3 each had a 28 day pre-conditioning period followed by a 30 day concentrate feeding period. Final fasted liveweight, liveweight gains, and carcass weights for concentrate, concentrate plus pasture and pasture alone groups were 546 ± 9, 548 ± 9, 547 ± 8 kg; 0.33 ± 0.09, 0.42 ± 0.09, -0.05 ± 0.09 kg/hd/day and 293 ± 7, 315 ± 4 and 313 ± 4 kg, respectively. The concentrate plus pasture and pasture only fed groups had greater fat depths. Ultimate pH was slightly lower in concentrate fed than pasture fed cattle but there were no differences in fat colour or tenderness as measured in the laboratory. Plasma carotene levels were significantly lowered by a factor of 10 in the concentrate fed group compared to the grass fed group, but this did not affect fat colour when measured subjectively at the meat processing plant or objectively in the laboratory. Apparently feeding concentrates for 30 days is insufficient to affect fat colour characteristics.

ST, Morris, RW Purchas, and DL Burnham

Proceedings of the New Zealand Society of Animal Production, Volume 57, , 275-277, 1997