Growth and carcass traits of 145 kg body weight pigs fed according to different feeding regimes

This study aimed to investigate the effect of feeding regimen on growth and carcass traits and estimated energy balance of pigs slaughtered around 145 kg body weight (BW) and addressed to high quality baked ham production. At the beginning of the trial, 96 crossbred barrows (Topigs Talent) averaging 30.4±4.1 kg BW were randomly allotted into 8 pens (12 pigs per pen) equipped with electronic feeding stations. All animals were provided with the same feeds containing on average 13.6 ME MJ/kg and 161 g CP/kg as-fed. Within each pen, 4 pigs were assigned to an ad libitum (AL), 4 pigs to a low-high restricted and 4 pigs to a high-low restricted feeding regime. Individual feed intake was recorded daily, pigs were weighed weekly, and backfat depth (P2) was measured with an ultrasound device every 3 weeks, till the end of the experiment, when the pigs averaged 142.6±7.8 kg BW. Measurements of BW and P2 were used to estimate changes of body composition over the time, from which ME requirements for protein and lipid growth were derived. Estimated ME for growth and the measured ME intake were used to estimate the ME used for maintenance. All pigs were slaughtered in the same day in a commercial abattoir, and carcass and major cuts weights were recorded. Samples of Longissimus Dorsi were collected for physical and chemical analysis. After 24 h of chilling thighs were deboned and weighed. Traits were analysed according to a mixed model which accounted for the effects of pen (random) and of feeding regime. Pigs fed AL showed (P<0.01) higher growth rate and final BW (966 vs. 832 g/d, and 145 vs. 141 kg, respectively), lower gain:feed and higher estimated amount of ME for maintenance than restricted fed pigs (0.368 vs. 0.383, and 0.98 vs. 0.89 MJ/kg BW0.60, respectively), whereas carcass and meat quality traits were similar among feeding regimes. Pigs fed different restricted feeding regimes gave similar growth and carcass performances. In conclusion, the AL feeding regime allowed to attain the target 145 BW some days earlier than restricted feeding regimes, but growth rate was not greater enough to compensate increased feed intake, thus penalising feed efficiency of AL fed pigs.