Effects of dietary linseed on nutritional value and other quality aspects of pig muscle and adipose tissue

This study reports improvements in the nutritional value of pork by including linseed in the diets of boar and gilt pigs. Two feeding strategies, either short-term or long-term, were employed: (i) 0 g or 114 g linseed per kg of food provided to 16 pigs of 87 kg live weight for 20 or 27 days; (ii) 0 g, 20 g, 10 g or 30 g linseed per kg of food provided to 64 pigs of 46 kg live weight for 54, 62, 68 or 75 days. All diets were supplemented with DL-alpha -tocopheryl acetate (0.2 g/kg). The 18:3n-3 contents (18:2n-6: 18:3n-3 ratios in parentheses) of the short-term 0 g and 114g/kg, and long-term 0 g, 10 g, 20 g and 30 g/kg linseed diets, were 2.1 g (7.75), 28.1 g (0.70), 1.0 g (8.86), 3.4 g (2.73), 6.0 g (1.66) and 8.1 g/kg food (1.25) respectively. The long-term 30 g/kg diet reduced the n-6:n-3 ratio of muscle and adipose tissue as successfully as the short-term 114 g/kg diet to accord with guidelines for the overall human diet (5:1 or less) but required only 0.73 as much linseed and increased the proportion of C20-22 n-3 fatty acids more effectively; compared with their respective control diets, the 114 g/kg and 30 g/kg diets more than halved the n-6 : n-3 ratios in muscle to 3.8 and 3.9, approximately trebled the concentrations of 18 :3n-3 in muscle to 0.43 mg and 0.28 mg/g tissue, and doubled the concentrations of 20:5n-3 in muscle to 0.08 mg and 0.10 mg/g tissue. Similar changes occurred in adipose tissue. With both strategies, the majority of the changes had occurred by the time the first groups were slaughtered. There was a strong relationship between the 18 : 2n-6 : 18 : 3n-3 ratio of the food and tissues and the accumulation of all C20-22 n-3 fatty acids, except 22:6n-3, which was unaffected by dietary linseed. The improvements in nutritional value were obtained without changes in organoleptic characteristics, as measured by a trained taste panel, or significant loss of shelf-life, as measured by TEARS analysis and colour stability.