Live-weight growth and efficiency of food utilization of purebred Galloway, Luing and Welsh Black steers, and crossbred steers out of Blue-Grey and Hereford × Friesian dams by Aberdeen-Angus, Charolais, Devon, Hereford, Limousin, Lincoln Red, Simmental, South Devon and Sussex sires, were examined in two suckled calf fattening systems. In one system, autumn-born calves were purchased at 1 year of age and fattened during their second winter; the other system involved late winter-born calves, which were purchased at 7 months of age, overwintered on a cheap growing diet and fattened during their second summer. The trial involved a total of 1430 cattle and extended over 5 years (winter system) and 6 years (summer system).
Cattle were slaughtered as close as possible to a standard carcass subcutaneous fat concentration.
The data for crossbred and purebred cattle were analysed separately within the fattening system using least squares models, which included effects for year, sire breed and dam breed, and with regression on the age at beginning of the trial and carcass subcutaneous fat concentration estimated by visual appraisal.
Breed differences in live weight at slaughter were similar to those recorded in the Meat and Livestock Commission's on-farm recording work. Among crossbreds, the larger sire breeds consumed more food per day, generally grew faster and were older at slaughter.
They did not differ significantly in the efficiency with which food was converted into live-weight gain. Among the purebreds, the Luing had a relatively high daily food intake in relation to its growth rate and, together with the Welsh Black in the summer fattening system, was less efficient than the Galloway (P<0·05).