Fatty acid composition and oxidative stability of lambs’ meat as affected by a bioflavonoid antioxidant and fat sources

Sc Slippers,Hj Van Der Merwe,Md Fair,Ob Einkamerer,Ke Booyens,A Hugo

doi:10.4314/sajas.v42i5.8

Abstract

A study was conducted to investigate the effects of a synthetic or natural antioxidant and fat saturation, in a standard feedlot diet, on fatty acid composition and oxidative stability of lamb. The four dietary treatments consisted of the same basal diet providing 187 g crude protein (CP), 355 g neutral detergent fibre (NDF), and 71 g ether extract (EE) per kg dry matter (DM), differing in fat source (30 g/kg of either saturated beef tallow or unsaturated soybean oil) and type of antioxidant included (125 g/t of either a synthetic or natural antioxidant). Eighty four S.A. Mutton Merino lambs weighing 27.6 ± 1.7 kg were divided into four groups and randomly allocated to four dietary treatments (n = 21 lambs/treatment) subdivided into 7 replicates/treatment (n = 3 lambs/replicate). After an adaptation period of 8 days, all lambs received complete diets for a further feeding period of 41 days. At termination of the study, seven lambs per treatment, weighing 45.1 ± 3.0 kg, were randomly selected and slaughtered. Loin chops from each carcass were used for fatty acid, colour (a* values) and thiobarbituric acid reactive substance (TBARS) analysis. Meat colour was determined on days 0 and 7 after being stored at 4 oC under fluorescent light. The malonaldehyde content per kg meat was determined on days 0, 7 and 90 after being stored at -18 oC in the dark. It was found that dietary treatment had no effect on colour stability as depicted in a* values. The malonaldehyde content per kg meat was higher on days 0 and 90 for the unsaturated soybean oil treatment. Beef tallow inclusion resulted in an increase in palmitoleic acid, where soybean oil inclusion resulted in an increase in linoleic and α-linolenic acids in both lean and subcutaneous fat tissue. Natural antioxidant inclusion in the diet only increased the palmitoleic acid content of subcutaneous fat. The results suggested that the fatty acid profile of lamb meat can be favourably manipulated by the source of fat included in the diet. Keywords: Antioxidants, dietary fat saturation, feedlot lambs

Highlights

In the last few decades there has been increasing interest in supplementary lipid sources in ruminant diets to increase the energy density of these diets and to improve the dietetic quality of the carcass and other ruminant products (Bauchart et al, 1996)
The four dietary treatments consisted of the same basal diet (187 g crude protein (CP), 355 g neutral detergent fibre (NDF) and 71 g ether extract (EE)/kg dry matter (DM)) only differing in the fat source (30 g/kg of either saturated beef tallow or unsaturated soybean oil) and type of antioxidant included
The inclusion of saturated tallow resulted in a higher (P

Summary

Introduction

In the last few decades there has been increasing interest in supplementary lipid sources in ruminant diets to increase the energy density of these diets and to improve the dietetic quality of the carcass and other ruminant products (Bauchart et al, 1996). Due to this demand, there has been an increased interest to find suitable and natural ways to positively manipulate the fatty acid composition of red meat (Wood et al, 2003).

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