Effects of dietary fat source, breed and vitamin E level on lipid oxidation of muscles from sheep

Gülcan Demi̇rel

doi:10.30704/http-www-jivs-net.489172

Abstract

The effects of diet and levels of dietary vitamin E on lipid oxidation were assessed in lambs in this study. Groups of Suffolk x Lleyn and Scottish Blackface male lambs were fed dietary lipid supplements containing either Megalac (C16:0), or one of two sources of n-3 PUFA: linseed which has a high content of C18:3 n-3, which had been treated with formaldehyde to aid rumen bypass and a mixture of formaldehyde treated linseed plus fish oil to provide EPA and DHA. The diets were based on dried grass had similar levels of fat (60g/kg DM). Vitamin E was included as α-tocopherol acetate at 100 and 500 mg/kg, for the low and high vitamin E diets, respectively. The six dietary treatments were: Megalac with low vitamin E, (ML); Megalac with high vitamin E, (MH); Protected linseed with low vitamin E, (LL); Protected linseed with high vitamin E, (LH); Protected linseed plus fish oil (linfish) with low vitamin E, (LFL); Protected linseed plus fish oil mixture (linfish) with high vitamin E, (LFH). At approximately half of the mature live weight for each breed, animals were slaughtered. This was on average 46 kg for the Suffolk and 36 kg for the Scottish Blackface. The meat from supplemented animals increased susceptibility to lipid oxidation in high PUFA in meat resulted from poor deposition of dietary vitamin E supplements.

Highlights

The nutritive quality of ruminant meat and its acceptability by consumers would be greatly enhanced if the proportion of unsaturated fatty acids were high and meat were stable to oxidation
The six dietary treatments were: Megalac with low vitamin E, (ML); Megalac with high vitamin E, (MH); Protected linseed with low vitamin E, (LL); Protected linseed with high vitamin E, (LH); Protected linseed plus fish oil with low vitamin E, (LFL); Protected linseed plus fish oil mixture with high vitamin E, (LFH)
Effects of diet, breed and vitamin E on TBA values and significance of the main effects and interaction are in Table 2. (a) semitendinosus muscle As a result of low vitamin E levels in muscle, TBA values was higher than acceptable value of 0.5-1.0 (Gray and Pearson, 1987) in muscles from all groups after 5 day simulated display

Summary

Introduction

The nutritive quality of ruminant meat and its acceptability by consumers would be greatly enhanced if the proportion of unsaturated fatty acids were high and meat were stable to oxidation. Dietary polyunsaturated fatty acids (PUFA) increase membrane unsaturation, as demonstrated in ruminants fed protected fats and increases the susceptibility of meat to oxidation (Wood and Enser, 1997). The role of supranutritional dietary levels of vitamin E for ruminants to maintain fresh beef colour and to elevate milk tocopherol which reduces lipid oxidation and resulting undesirable milk flavours, has been demonstrated (Arnold et al, 1993; Chauhan et al, 2014). Wulf et al (1995) reported that feeding sheep 500 mg α-tocopherol per day improved lipid stability and colour shelf life for up to four days, when the tissue levels of vitamin E were in excess of 5.5 mg/kg.

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