Abstract
In total, 192 Iberian pigs were used to investigate the effects of net energy (NE) concentration of the diet on growth performance and carcass quality of castrated females (CF) and castrated males (CM). From 30 to 112 kg body weight (BW), three diets were formulated with similar digestible amino acid content per kcal of NE but differing in energy concentration (2,045, 2,175 and 2,305 kcal NE kg-1 from 30 to 81 kg BW and 2,175, 2,305 and 2,445 kcal NE kg-1 from 81 to 112 kg BW). From 112 kg to slaughter (148 kg BW), all pigs received a common finisher diet. Each treatment was replicated eight times and the experimental unit was a pen with four pigs. A decrease in NE concentration of the diet increased feed intake (p<0.05) and tended to impaired feed conversion ratio (p<0.10), whereas carcass and meat quality traits were not affected. Castrated males ate more feed and grew faster but had less fat thickness at the gluteus medius muscle than CF (p<0.05). However, no differences in carcass and meat quality traits between genders were detected. We conclude that a reduction in NE content of the grower diets did not affect growth rate and therefore, it not a valuable alternative to avoid excess of BW at slaughter in Iberian pigs reared under intensive management conditions. Also, both genders can be used for the production of high quality carcasses destined to the dry-cured industry.
Highlights
Iberian (IB) pigs have been reared under extensive production systems with acorns and grass as main nutrient sources
Current legislation (BOE, 2007a) allows the use of Duroc sires to improve productive eff iciency of IB pigs but the crossbreds must be slaughtered with at least ten months of age. At these ages IB × Duroc pigs fed concentrates are heavier than required by the industry, with poorer feed efficiency and carcasses that are too fat
Because of the heavy body weight (BW), primal cuts are of excessive size and not well adapted to consumer preferences
Summary
Iberian (IB) pigs have been reared under extensive production systems with acorns and grass as main nutrient sources. The development of the Iberian pig industry is based primarily on the production of pigs reared indoors and fed concentrates. Current legislation (BOE, 2007a) allows the use of Duroc sires to improve productive eff iciency of IB pigs but the crossbreds must be slaughtered with at least ten months of age. At these ages IB × Duroc pigs fed concentrates are heavier than required by the industry, with poorer feed efficiency and carcasses that are too fat. When IB × Duroc pigs are Abbreviations used: a* (redness); ADFI (average daily feed intake); ADG (average daily gain); b* (yellowness); BF (backfat); BF1 (backfat thickness measured perpendicular to the dorsal midline at the level of the last rib); BF2 (backfat thickness measured from 6 cm of the dorsal midline at the level of the last rib); BF3 (backfat thickness measured at the lateral edge of the longissimus dorsi muscle from the skin to the muscle); BW (body weight); c* (chroma); CF (castrated female); CM (castrated male); CP (crude protein); EN (net energy); FCR (feed conversion ratio); GE (gender); GM (gluteus medius muscle); H (high); H° (hue angle); HC (castrated female); IB (Iberian); L (linear); L* (lightness); Lo (low); LM (longissimus dorsi muscle); M (medium); MC (castrated male); NE (net energy); pH24 (pH at 24 h post mortem); PV (body weight); Q (quadratic); RH (relative humidity); SEM (standard error of the mean); SM (semimembranosus muscle)
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