THE USE OF LASALOCID IN LONG-TERM FEEDING OF FRIESIAN STEERS

Seventy-two Friesian calves with a mean (+/- s.e.) liveweight of 130.6 +/- 3.82 kg were divided into 8 groups which were then allocated to 2 dietary treatments, a grain-based feedlot diet (Cent) and the same di et with lasalocid added at the rate of 22 g/t (Las). After 127 days (p eriod 1) of feeding, 2 of the groups in the Cent treatment were change d to the Las treatment (Cent double right arrow Las) and 2 on the Las treatment were changed to the Cent treatment (Las double right arrow C ent). The animals were slaughtered after a further 168 days of feeding (period 2). Liveweight gain of the Las group (1.39 kg/steer.day) was superior to that of the Cent group (1.28 kg/steer.day) in period 1. In period 2, liveweight gain in the Las and Las double right arrow Cent groups was superior to that of the Cent double right arrow Las group. Food conversion ratio in the Las group was lower than in the Cent grou p during period 1 but there were no differences between treatments in period 2. The slaughter data showed that the Friesian steers produced acceptable carcasses in terms of carcass weight and fat depth. The stu dy showed that Friesian steers can be successfully grown to slaughter weight on high grain diets and that long-term lasalocid supplementatio n results in improved liveweight gain and feed conversion efficiency.