Influence of production system and feeds on performance, carcass traits and estimated energy balance of autochthonous Gochu Asturcelta pigs

Aim of study: To assess the effects of rearing system (extensive, ES; semi-extensive, SES) and feeds (grazed woodland, acorns, chestnuts, compound feed) on the performance, carcass traits and energetic balance of autochthonous Gochu Asturcelta pigs. Area of study: Asturias (Spain). Material and methods: In two successive years, a total of 58 immunocastrated Gochu Asturcelta pigs (25 females, 33 males), with an initial weight of 93.39 +/- 3.36 kg and mean age of 6.82 +/- 0.24 months, were randomly divided between ES and SES plots from July to December. ES pigs grazed woodland, acorns (Quercus robur L.) and chestnuts (Castanea sativa Mill.) and they were given additionally 1.5 kg compound-feed/pig.day. SES animals received only 2.5 kg compound-feed/pig.day. Chemical composition and metabolizable energy (ME) of feeds, energetic balance, growth performances and pig carcass traits were analysed. Main results: Acorns and chestnuts were both very close in their chemical composition, except for the polyphenol content and profile, and had a lower omega-6/omega-3 ratio than compound feeds. Live weight for the ES pigs was 25% lower and carcass weight 30% lower than for SES pigs (p<0.001). Total ME requirement (MJ/day) was lower in ES than in SES pigs. Research highlights: The productive and carcass parameters observed are a consequence of a lower energy intake for pigs in ES than in SES, it being necessary to drastically reduce the stocking rate to increase weight gain and to improve carcass traits when Gochu Asturcelta pigs are reared in ES.