Growth Performance and Carcass Traits in Purebred Apulo-Calabrese and Crossbred (Apulo-Calabrese × Goland) Pigs Fed...

Preserving the Apulo-Calabrese (AC), an endangered Italian autochthonous pig breed, requires sustainable nutritional strategies that improve pork quality without compromising productive performance. This study evaluated the effects of dietary supplementation with extruded linseed, alone or combined with grape pomace powder, rich in antioxidants, on growth performance and carcass traits in purebred Apulo-Calabrese (AC) pigs and Apulo-Calabrese × Goland (AC × G) crossbred pigs. Two independent feeding trials were conducted using three dietary treatments: a control diet (CTR), a diet containing 5% extruded linseed (SL), and a diet containing 5% extruded linseed plus 0.2% grape pomace powder rich in polyphenols (SLXI). Thirty-six purebred AC pigs reared outdoors, and 30 AC × G crossbred pigs reared indoors were included in the study. Body weight (BW) and average daily gain (ADG) were recorded throughout the trials, while hot carcass weight (HCW), carcass yield (CY), pH45, pH24, and backfat thickness (BF) were evaluated at slaughter. Data were analyzed separately for the two trials using Linear Mixed Models. Feed intake was complete in all groups, indicating good diet palatability. In purebred AC pigs, dietary treatment significantly affected overall ADG, with CTR pigs showing higher ADG than SLXI animals, while SL displayed intermediate values not significantly different from either CTR or SLXI. BW and carcass traits were not significantly influenced by diet. In addition, a significant Diet × Time interaction was detected for ADG (p = 0.010), indicating diet-dependent growth patterns over time. Sex did not significantly affect BW, ADG, or carcass traits in purebred pigs. In crossbred AC × G pigs, dietary treatments could not be evaluated inferentially due to the lack of pen-level replication; therefore, growth and carcass data are presented descriptively. However, Sex significantly affected carcass yield, with males showing higher CY than females (p = 0.004), while BW, ADG, and the remaining carcass traits were not influenced by Sex. The results suggest that extruded linseed, alone or combined with low-dose grape pomace powder, can be included in diets for purebred and crossbred pigs without compromising growth performance or basic carcass traits. These findings support the use of powdered grape pomacein feeding strategies aimed at the valorization and conservation of Apulo-Calabrese pig genetic resources. Further studies are needed to evaluate the effects of these dietary strategies on meat fatty acid composition, oxidative stability, sensory quality, and shelf life.