THE EFFECT OF A PROGESTERONE ESTRADIOL EAR IMPLANT ON THE PERFORMANCE OF YOUNG BEEF STEERS

A progesterone/estradiol ear implant was tested over a 84 d feedlot period on 96 young Bonsmara steers which were randomly allocated to implant and control groups. Animals were adapted over 5 d to a complete feed formulated to South African feedlot standards. Health aberrations were observed and feed intake, mass gain and slaughter data were recorded. The implant group elicited a 23,2 kg gain per animal (P < 0,01). Mean treatment feed intakes varied marginally but the implant group showed a 14,91% feed to gain improvement over controls. Warm carcass dressing percentage showed an overall improvement of 4,96% for both groups. Bloat incidence was calculated at 0,98% over 8 064 cattle feedlot days. Mortality was 2,08% and 12 animals were considered to be chronic bloaters. This may have been due to the high proportion of fine particles in the diet. A composite feed sample revealed that 62,48% consisted of particle lengths of 0,5 - 4mm. The effect of this on ruminal health is briefly discussed. It is concluded that the progesterone/estradiol implant provided greater mass gain and improved feed to gain ratios for treated steers over a control group.