Effects of Dietary Energy Level and Slaughter Weight on Growth Performance and Grades and Quality Traits of the Carcass in Finishing Pigs

(Y × L) × D-crossbred gilts and barrows weighing 80.2±0.2 kg were fed a "medium-energy" (ME) or "low-energy" (LE) diet (3.2 vs 3.0M cal DE/kg) and slaughtered at 110, 125, or 138kg, after which physicochemical and sensory quality traits of major primal cuts of resulting carcasses were analyzed, under a 2 (sex) × 2 (diet) × 3 (slaughter weight; SW) factorial arrangement of treatments. The ADG and ADFI were greater (P less than 0.01) in barrows than in gilts and also in 125- and 138-kg vs 110-kg SW. Moreover, ADG and gain:feed were greater in ME vs LE (P less than 0.01), whereas ADFI was greater in LE vs ME (P less than 0.01). Backfat thickness, which increased with increasing SW (P less than 0.01), was not affected by sex or diet. Carcass marbling score was greater (P less than 0.01) in gilts and LE than in barrows and ME, respectively. Carcass quality grade, which was superior in LE vs ME, was not affected by SW, whereas the yield grade decreased abruptly between 125- and 138-kg SW primarily due to the upper limit of carcass weight imposed on the A and B grades. Physicochemical characteristics including pH, drip loss, and variables pertaining to color of belly, ham, and loin were not affected significantly by any of the treatment factors, albeit statistically significant in some cases, in terms of quality criteria. In sensory evaluation, the acceptability of fresh belly was not influenced by any of the treatment factors. Marbling score of fresh ham was greater in LE vs ME (P less than 0.01) and tended to increase between 110- and 125-kg SW (P=0.10); in loin, the increase of this variable between the two SW was significant (P less than 0.01). Following cooking, LE was superior to ME in the acceptability in belly and ham, but the effect of SW was insignificant in any of the sensory quality traits evaluated in this study in any of the three major primal cuts. In conclusion, the present results suggest that SW can be increased to up to 138 kg without compromising carcass quality and that LE has some beneficial effects on quality of the whole carcass and the major primal cuts.