Rearing System & Muscle Lipids of Gilts and Castrated Pigs

Background and methodology
Pigs reared free-range are believed to be healthier and better able to satisfy their natural urges and behavior. However, free range rearing system might affect meat composition and quality. Some studies have concluded that there was greater proportion of unsaturated fatty acids in the total lipids in free-range pig muscle due to grazing, as grass generally contain high levels of 18:3n-3. The objectives of this study were to establish if and how free range rearing of pigs influences the fatty acid composition in the neutral lipids and polar lipids and to evaluate sex-related differences in the fatty acid composition of these lipid classes. A total of 120 Hampshire crossbreeds were divided in two groups, one reared as free-range and one reared indoors.

Free-range rearing produced a more unsaturated fatty acid composition in the neutral lipids, although the effect was small. In the polar lipids the effect of rearing condition was sex dependent. In the muscles of free range gilts there was a higher level of C18:2n-6, compared with indoor gilts, indoor castrates and free-range castrates. Muscles of gilts irrespective of rearing condition had higher level of the C≥20 polyunsaturated fatty acids in the polar lipids (16.75 and 14.60 respectively). The study suggested that the difference between castrates and gilts with respect to fatty acid composition in the polar lipids might be affected by rearing condition.

Högberg, A., Pickova, J., Dutta, P. C., Babol, J. & Bylund A.C. (2001). Effect of rearing system on muscle lipids of gilts and castrated male pigs. Meat Science 58: 223-229.