Production efficiency of South African Mutton Merino lambs and Boer goat kids receiving either a low or a high energy feedlot diet

Abstract

Individual feed consumption, utilisation, digestion efficiency and growth of 32 Boer goat (BG) kids and 32 South African Mutton Merino (MM) lambs were investigated after weaning. Two pelleted diets (fed to 16 animals per species) with either a low (LE, 9.89 MJ kg−1 DM) or a high (HE, 12.11 MJ kg−1 DM) metabolisable energy level were fed individually, ad lib, for either 28 or 56 days. MM had significantly higher average daily gains (ADG) than BG. Within a diet there was no significant difference in feed conversion efficiency (FCE) between BG and MM and only the MM FCE differed between the LE- and HE-diets. BG fed LE digested DM, CP and energy more efficiently and had a higher energy retention than MM fed LE. Neither species, nor diet affected N retention. The average daily gain of the MM on the LE-diet for 28 days was significantly lower than for those on the HE-diet. However, there was no significant difference between the ADG of BG on the high or low energy diets. These trends were similar in the group of animals that were fed for 56 days. These results indicate that Boer goats may be finished on a diet with a lower ME-value than is usually formulated for sheep, without a reduction in performance. This may render the BG economically viable for feedlot finishing.