Responses of growing pigs of different sex and breed to different energy levels

Results of the first experiment showed that at 40 to 75 kg liveweight, there was a significant (P0.05) increasing growth rate [GR], energy intake [EI], backfat thickness [BFT] and P2 measurements of both barrows and gilts with increasing energy level [EL] in a linear manner. A significant (P0.05) decreasing average daily feed intake [ADFI], energy efficiency [EE] and feed conversion ratio [FCR] was noted on both the barrows and gilts. At 75 to 90 kg liveweight, both barrows and gilts followed a linear-plateau response on GR while BFT and P2 measurement increase with increasing EL in a linear manner. No significant differences were noted on ADFI, EI, and EE on both sexes. There was a significant (P0.05) decreasing number of days to reach 90-kg liveweight with increasing EL on both sexes. Barrows had significantly (P0.05) higher GR and EI, BFT, and P2 measurement than the gilts on the first and second phase of feeding. Moreover, barrows had significantly (P0.05) shorter days to reach 90 kg liveweight than the gilts. The maximum protein deposition rate of barrows is at 123 g/day at 3100 ME kcal/kg EL in the diet and 124 g/day for the gilts at EL of 32 ME kcal/kg. At 40 to 90 kg liveweight, LW x LD pigs responded significantly (P0.05) to increasing EL with increasing average daily gain [ADG] and EI. A significant (P0.05) decreasing ADFI and FCR was noted with increasing EL in the diet. Barrows had significantly (P0.05) higher ADG and EI compared with the gilts. However, gilts are significantly (P0.05) more efficient energy converters than the barrows. In the second experiment, it was noted that at 40 to 70 kg liveweight, both the LD and LW gilts responded significantly (P0.05) to increasing EL with increasing rate of gain, EI, BFT and P2 measurement in a linear manner. A significant (P0.05) decreasing EE and FCR were noted with increasing EL in the diet. At 75 to 90 kg liveweight, both LD and LW gilts had significant (P0.05) increasing ADG, BFT and P2 measurements. However, LW gilts had significant (P0.05) linear GR up to 3100 ME kcal/kg in the diet and only a slight increase but not significant (P0.05) from 3100 to 3200 ME kcal/kg. LD gilts had a significant (P0.05) linear GR from 2900 to 3200 ME kcal/kg. No significant (P0.05) differences were noted on ADFI, EI with increasing EL. LW gilts had significantly (P0.05) higher GR, EI, protein deposition rate [PDR], EE and a significantly (P0.05) lower feed efficiency, BFT, P1 and P2 measurements than the Landrace gilts. Maximum PDR of LW gilts is at 123 g/day at 3100 ME kcal/kg EL in the diet while LD gilts is 118/day at 3200 ME kcal/kg