Backfat firmness is an important aspect of pig carcass quality. National values for backfat thickness have been falling annually whilst softer backfat has been increasingly reported by the meat trade. The problems of soft backfat have been well documented: it is unsightly, difficult to slice and prone to separation (MLC, 1983). All these factors can lead to downgrading of the product and consequent financial loss to the processor. Leanness of pigs is one cause of softer backfat and unsaturation of the backfat lipid, especially by the exogenous fatty acid linoleic acid (C18:2), is also an important factor (Prescott, 1988). The present study investigates the effect of backfat thickness and consequent chemical composition on fat tissue quality and considers some histological aspects of the soft fat problem.

Forty-six NPD gilts were reared to obtain carcasses having a wide range of backfat thickness values at a slaughter live weight of 90 kg. Two diets containing different levels of linoleic acid and energy but the same ratios of linoleic acid to energy were used to achieve this.