The use of multivariate analysis for evaluating relationships among fat depots in heavy pigs of different genotypes

The aim of the present work was to study distribution and reciprocal relationships of fat depots in heavy pigs of several genetic types. On 161 barrows and gilts belonging to four genetic types (Large White and relative crosses with Italian Landrace, Belgian Landrace and Duroc), slaughtered from 125 to 180 kg l.w., thickness, colour (C.I.E, L*, a*, b*) and weight of backfat and of kidney fat were determined. Subcutaneous and intermuscular fat of ham were weighed. On biceps femoris, semimembranosus and semitendinosus muscles ether extract content was determined. Allometric analysis showed that body growth did not particularly increase the intramuscular fat content of the ham. Principal component analysis indicated that PC1 (0.43% of variation) represented the overall fatness, associated all the depots in a similar manner, and was linked to body weight and sex. PC2 (0.22% of variation), linked to genotypes and body weight, expressed the opposition between intramuscular fat deposition and subcutaneous and internal fat accumulation. Using measurements easily recorded on the side (backfat thickness and colour, percent kidney fat), only the estimate of subcutaneous fat, among ham depots, showed good accuracy (R2=0.65).