Purpose of the study was to assess the effect of season on cultural energy analysis of beef cattle production systems. For this purpose, a summer feeding trial involving 188 yearling steers, with a mean body weight of 299 kg which started on 28 April and finished on 3 October and a winter feeding trial involving 182 yearling steers, with a mean body weight of 327 kg which started on 8 November and finished on 12 April were compared. In each season, housing consisted of three outside lots with access to overhead shelter, three outside lots with no overhead shelter and a semi-enclosed (open-front) cold confinement building containing four lots. Ad libitum corn grain, 2.27 kg of 35% dry matter (DM) whole plant sorghum silage and 0.68 kg of a 61% protein-vitamin-mineral supplement was offered. Cultural energy (CE) used for feed and other production inputs was derived from their corresponding lot feed consumption and their corresponding values from the literature. Transportation energy was also included in the analysis. Cattle fed in summer had higher total CE expenditure than those fed in winter (P<0.05). Feed energy constituted more than half of the total CE and was higher for summer fed cattle (P<0.05). Energy inputs/kg live weight and/kg carcass were lower for summer fed cattle (P<0.05). Cultural energy per Mcal protein energy was higher for winter fed cattle (P<0.05). The energy output ratio defined as the Mcal input/Mcal output was better for summer fed cattle (P<0.05). Results show that time of year feeding affects cattle performance and CE use and summer feeding is an effective way of increasing the sustainability of beef cattle production.