Effect of dietary lard on performance, fatty acid composition and susceptibility to lipid peroxidation in growing-finishing female and entire male pigs

Abstract

The effect of increasing the energy concentration of growing-finishing pig diets through inclusion of lard on performance, carcass and meat composition and lipid susceptibility to peroxidation was studied. A total of 720 Landrace × Large White male and female pigs (equal number of entire males and females) were used. Experimental diets were formulated to have a low (3000 kcal ME kg-1) or high (3200 kcal ME kg-1) energy level, but in all cases to have a constant lysine:ME ratio. This was achieved using a low (6.8 g kg-1) and a high (49.3 g kg-1) level of dietary lard inclusion. Gilts had lower daily gain (P < 0.0001) and worse feed conversion efficiency (P < 0.0001) than entire males. Susceptibility to oxidation was not affected by sex. Fat concentration in pig diets equilibrated in metabolizable energy and protein did not modify average gain, but reduced feed intake (P < 0.02), improved the gain:feed ratio (P < 0.0001 ), increased dressing percentage (P < 0.02) and produced higher carcass weight (P < 0.01). Carcass backfat and lean percentage were not affected by dietary treatment. A reduction in the proportion of (n-3) fatty acids in phospholipids (P < 0.03), a higher (n-6):(n-3) ratio (P < 0.01) and a lower susceptibility of muscle homogenates to oxidation was found in animals receiving higher levels of dietary lard (P < 0.01).