The effect of dietary non-protein nitrogen content on the meat quality of finishing lambs

Abstract

The effect of increasing the non-protein nitrogen content of low-fibre finishing diets on the meat quality of South African Mutton Merino wether lambs was investigated. Four similar dietary treatments were formulated with different non-protein nitrogen contents (16.6 g/kg, 28.3 g/kg, 40 g/kg, and 51.7 g/kg) on a dry matter basis. The study was conducted over 71 days. Muscle lipid content was higher on the 40 g/kg compared to 16.6 g/kg and 28.3 g/kg non-protein nitrogen diets. Myristic acid and total saturated fatty acid content of lamb muscle tissue was higher, whereas the total unsaturated fatty acid content of the same tissue was lower following a high dietary non-protein nitrogen content. A high nonprotein nitrogen diet (51.7 g/kg) reduced conjugated linoleic acid content of adipose tissue, compared to 28.3 and 40 g/kg non-protein nitrogen treatments. Malonaldehyde content of fresh lamb meat was higher on the 28.3 g/kg compared to the 16.6 g/kg non-protein nitrogen diet. The malonaldehyde content of the treatment containing 40 g/kg non-protein nitrogen was higher than the 51.7 g/kg when stored for 90 days. Therefore, the non-protein nitrogen content of low-fibre lamb finishing diets does not affect mutton fatty acid composition and quality parameters. Protein quality and its effect on ruminant meat quality requires more attention.