Free-range Pigs: Meat Quality and Adipose Tissue Composition

Background and methodology
This study was undertaken to evaluate the effect of rearing environment on growth performance, carcass characteristics, muscle metabolic traits and meat quality traits of three muscles in pigs differing in functional role and anatomical location. 
Forty large White gilts and barrows were blocked by weight within each gender and allotted randomly into two groups of pigs reared indoors (IN) and those reared outdoors (OUT). Both groups had free access to the same grower-finisher diet.

The OUT pigs had lower (P<0.05) ADG and leaner (P<0.05) carcasses. Rearing environment did not (P>0.63) affect the intramuscular lipid content of the semitendinosus (ST), but intramuscular lipid content was lower (P<0.01) in the longissimus muscle (LM) and tended to be higher (P=0.06) in the rectus femoris (RF) of out than in those of IN pigs. In the backfat outer layer of OUT pigs, the higher PUFA content was compensated by both lower (P<0.01) saturated and monounsaturated fatty acid (MUFA) content, whereas in the omental fat (OF), LM and dark portion of the ST, only the percentage of MUFA was decreased (P<0.01). In all tissues of the OUT pigs, the linoleic acid content was higher (P<0.01) and the n-6:n-3 ratio was lower (P<0.01). The results suggest that rearing pigs outdoors has little concomitant influence on meat quality traits.

Bee, G., Guex, G. & Herzog, W. (2004). Free-range rearing of pigs during winter: Adaptations in muscle fiber characteristics and effects on adipose tissue composition and meat quality traits. J. Anim, Sci. 82:1206-1218.