Characterisation and development of 'the shield' in male pigs

A project was undertaken to characterise boar shield, study its development and determine whether it presents carcass quality problems in young boars used for meat production. In two old boars (>2·5 years) 'backfat' from the scapular region consisted mainly of a dense white tissue with a high collagen content (>20% of fresh weight) and a low lipid content (<10%) compared with normal backfat. Histologically and chemically it resembled the dermis of skin. In a development study in boars and castrates from the Large White and Pietrain breeds, collagen concentration in scapular backfat increased between 91 and 118 kg liveweight in all pigs but the increase was greater in boars than castrates and especially marked in Pietrain boars in which the mean collagen concentration was 18% at 118 kg. This was probably because of the older age of Pietrains since there was a high correlation between age and collagen concentration (r = 0·93). The results suggest that, at 'heavy hog' weights, boar shield could present a carcass quality problem in slow-growing breeds such as the Pietrain.