Published online by Cambridge University Press: 02 September 2010
A total of 178 castrated male cattle (steers), the progeny of Charolais, Hereford and Limousin bulls mated to Holstein-Friesian and Ayrshire cows, were raised from 8 months of age to 545 kg (slaughter weight) on fast- or slow-gaining regimes. The steers on the fast gaining regime were fed a grain mixture with little hay, while those on the slow-gaining regime grazed all summer and were wintered on hay supplemented with a little grain.
The steers on the fast-gaining regime were more efficient in feed conversion ratio, had 0·42 kg per day higher live-weight gain, reached slaughter weight 306 days earlier, and had 2% higher dressing-out percentage, 5·7 mm thicker fat and 5 mm2 larger area of m.longissimus thoracis than those on the slow-gaining regime.
Charolais-sired steers on both regimes had the fastest gain and were the first to reach slaughter weight. Limousin-sired steers raised on the fast-gaining regime had the highest dressing-out percentage, and the largest area of m. longissimus thoracis on both regimes. Hereford-sired steers had the thickest fat cover and the smallest area of m. longissimus thoracis. Little difference was found between the steers from Holstein and Ayrshire cows.