Effect of tomato by-products in the diet of Comisana sheep on composition and conjugated linoleic acid content of milk fat

Abstract

To evaluate the effect of supplementing the diet of Comisana sheep with by-products from industrial tomato manufacture on the fat composition and conjugated linoleic acid (CLA) content of milk fat, two groups of 50 ewes each were fed either total mixed ration standard (TMRS) or total mixed ration with added tomato by-products (TMRA). Milk fat composition was determined by high-resolution gas chromatography (HRGC). The milk fat content for the animals fed the TMRA diet increased by 6.41% ( P < 0.01) after six weeks, compared with the animals fed the TMRS diet. The CLA content in the milk fat for the group of animals fed the TMRA diet was 19.8% ( P < 0.05) higher than for those fed the TMRS diet, and reached 1.33 g 100 g −1 fat, while the polyunsaturated fatty acid (PUFA) content increased by a 6.43% ( P < 0.05) and reached 7.12 g 100 g −1 fat. The fatty acid composition showed an increase in the amount of polyunsaturated fatty acids. The n − 3:n − 6 ratio increased by 13% in the milk from sheep fed with the TMRA diet. These observations were confirmed by triglyceride analysis, which showed a decrease in the amount of short-chain (C 28–C 32) and medium-chain (C 34–C 42) triglycerides after six weeks, while the opposite was observed for the long-chain triglycerides (C 44–C 54).