Responses of growing pigs (Sus domesticus L.) of different sexes and breeds to different energy levels

Study 1 showed a clear effect of energy level on body weight, growth rate, energy intake, and carcass characteristics of both barrows and gilts. Weight gain of the animals was dependent on energy level in the diet. There was a faster growth rate for both sexes at higher than lower liveweight. Increasing energy level in the diet resulted in a decreasing average daily feed intake and feed conversion ratio. However, there was an increasing energy intake with increasing energy level. There was a significant (P0.05) decrease in number of days to reach the 90 kg liveweight with increasing energy level. There was a significant (P0.05) linear response for both sexes on backfat thickness and P2 measurements both increasing with increasing energy level in the diet. Regardless of sex, crossbred LW x LD [Large white x Landrace] had a linear response on the rate of PD [protein deposition]. Study 1 on crossbred LW x LD showed the effects of energy level in the diet on the body weight of animals. The same trend was observed for both purebred LD and LW gilts. At 40-75 kg liveweight, the pigs responded to increasing energy level with increasing rate of gain in a linear manner. At 40-90 kg liveweight, the LW gilts had significantly (P0.05) higher ADG than the LD gilts. The analyses showed a linear-plateau relationship between energy level and growth rate for both LW and LD gilts. There was a significant (P0.01) treatment x breed interaction on the energy intake of gilts. A linear increase in energy intake was noted with increasing energy level in the diet. LD gilts had a significantly (P0.05) higher energy intake than LW gilts. A significant (P0.01) treatment x breed interaction was noted on energy efficiency, with LW gilts proving to be more efficient energy converters than LD gilts. A highly significant (P0.01) linear increase response in terms of backfat thickness and P2 measurement was noted in both LD and LW gilts. The LD gilts deposited more fat than did the LW gilts. It was noted that increasing energy level in the diet resulted in increased energy intake and fatter bodies. On the average, PDR [protein deposition rate] increased in a linear manner with increasing energy level