Goats are more commonly reared in extensive production systems in South Africa and are directly marketed from the farm at a weight of less than 30 kg. This study was performed to determine the effect of dietary energy content on the production of South African Boar goats in a feedlot system to be able to increase marketing weight. In this trial, 53 Boer goats were randomly divided into 3 dietary treatments that varied in energy content, giving a low, 11.3 MJ ME/kg feed (18 goats), medium, 12.0 MJ ME/kg feed (16 goats) and high energy diets, 12.7 MJ ME/kg feed (19 goats). The diets were equal in terms of crude protein (17.0%), calcium (0.86%) and phosphorus (0.36%). These goats were reared in individual pens for a period of 8 weeks, where the trial diets were fed on an ad libitum basis and growth and feed intake were monitored. Initial body weight was 22.4 kg and after 8 weeks the goats on the medium diet had gained the most weight, weighing 34.6 kg followed by the low energy (33.4 kg) and the high-energy diets (31.4 kg). The difference between the 3 treatments were significant at P = 0.01. The average daily gains differed significantly (P = 0.036) with goats on the medium energy diet attaining the highest ADG of 0.253 kg/day, while goats on the high-energy diet had the lowest ADG of 0.183 kg/day. This suggests that the energy content of the medium energy diet is probably close to the energy requirements of the goats, while the low diet does not contain sufficient energy to maintain higher growth rates. Goats are also not adapted to digest feeds with high-energy contents and therefore can probably not use the excess energy for growth. Feed intake differed between the 3 treatments (P < 0.001) with the goats on the low energy diet having the highest DMI of 1.456 kg/day which decreased with an increase in dietary energy content (1.112 kg/d for the high energy diet). The feed intake for the medium energy group was intermediate at 1.284 kg/d. The feed conversion ratio (FCR) did not differ significantly for the 3 treatments and was calculated to be 6.61 kg feed/kg weight gain. Goats fed the medium energy diet displayed the best growth at a moderate feed intake, even though the FCR between the diets did not differ significantly.