Productive response of Duroc x Large White and Commercial Hybrid x Large White crosses fed high and low protein diets

Thirty five Duroc x Large White (DUxLW) and 43 Commercial Hybrid x Large White (CHxLW) were fed two diets differing for the content of crude protein (CP), with the aim to evaluate the effects of these diets on growth, carcass and thigh traits. Pigs were allotted to two groups and fed high protein (HP) and low protein (LP) diet. Within each dietary group, 3 diets were formulated, for the initial phase of growth (from 79 to 112 days, 17.3% and 15.4% CP as fed basis for the HP and LP diet, respectively), for the intermediated phase of growth (from 113 to 196 days, 15.1% and 13.7% CP as fed basis for the HP and LP diet, respectively) and for the finishing period (from 197 to 272 days, 13.4% and 11.4% CP as fed basis for the HP and LP diet, respectively). HP diets were supplemented with Lysine, LP were supplemented also with Methionine and Threonine. Pigs were slaughtered at nine months of age. Body weight (BW), average daily gain, total feed intake and feed conversion ratio were not affected by diet. Carcass weight, thigh weight, backfat and lean thickness and lean percentage (Fat-O-Meater, FOM) were not affected by dietary treatments, whilst backfat thickness and FOM were significantly higher (P<0.01) in DUxLW and CHxLW pigs genotype respectively. A reduction of about 15% (12% to 17%) of the dietary CP recommended by nutritional requirements does not affect the main productive performances and carcass characteristics of pigs slaughtered at around 160 kg of BW.