Abstract
We investigated the effect of various dietary polyunsaturated fatty acid (PUFA) sources on the fatty acid profiles of muscle, liver, heart and kidney of Australian prime lambs. Seventy-two White Suffolk x Corriedale first-cross lambs weaned at 6 months of age were randomly allocated to the following six treatments: (1) Control: Lucerne hay only; wheat-based pellets infused with 50 ml/kg dry matter (DM) of oil from (2) rice bran (RBO); (3) canola (CO); (4) rumen-protected (RPO), (5) flaxseed (FSO) and (6) safflower (SO) sources in a completely randomized experimental design. Lambs in CO, FSO, SO and RPO treatments achieved contents of eicosapentaenoic acid (EPA, 22:5n-3) plus docosahexaenoic acid (DHA, 22:6n-3) in the longissimus dorsi muscle ranging from 31.1 to 57.1 mg/135 g, over and above the 30 mg per standard serve (135 g) threshold for “source” claim under the Australian guidelines. There was no difference in n-3 LC-PUFA contents in longissimus dorsi muscle of lambs fed dietary oils of plant origin. The highest 18:3n-3 (ALA) contents achieved with FSO diet in the muscle, liver and heart were 45.6, 128.1 and 51.3 mg/100 g, respectively. Liver and kidney contained high contents of n-3 LC-PUFA (ranging from 306.7 to 598.2 mg/100 g and 134.0 to 300.4 mg/100 g, respectively), with all values readily exceeding the ‘good source’ status (60 mg per serve under Australian guidelines). The liver and kidney of PUFA fed lambs can be labelled as ‘good source’ of n-3 LC-PUFA based on EPA and DHA contents stipulated by the Food Standards of Australia and New Zealand guidelines. Therefore, if lamb consumers consider eating the liver and kidney as their dietary protein sources, they can adequately obtain the associated health benefits of n-3 LC-PUFA.
Highlights
Accumulating scientific evidence demonstrates the important role that omega-3 long-chain (>C20) polyunsaturated fatty acids (n-3 LC-PUFA) play in conditions such as cardiovascular disease, certain cancers and other diseases[1,2]
The remaining treatments were rich in PUFA and n-6 PUFA with relatively high levels ranging from 39 to 59 (%) and 34 to 57(%), respectively, in which the major fatty acids were lucerne hay were 18:2n-6 (LA) and 18:1n-9
Supplementation of lambs with PUFA enhanced pellets in a feedlot system is needed to boost the contents of n-3 LC-PUFA in the longissimus dorsi muscle
Summary
Accumulating scientific evidence demonstrates the important role that omega-3 long-chain (>C20) polyunsaturated fatty acids (n-3 LC-PUFA) play in conditions such as cardiovascular disease, certain cancers and other diseases[1,2]. Humans like all other mammals, cannot synthesise n-3 LC-PUFA because they lack the necessary Δ12 and Δ15-desaturase enzymes These health-benefitting fatty acids must be supplied in the diet[5]. Ruminant meat research has drawn considerable attention because ruminant meat contains some bioactive lipids (including n-3 LC-PUFA) and the fatty acid profiles of ruminant meat can be enhanced through dietary supplementation[7,8]. Supplementing prime lambs with 5% flaxseed or canola oil pellets increased n-3 LC-PUFA in the liver, heart, kidney and longissimus thoracis et lumborum muscle tissue[10,11]. We hypothesised that the fatty acid profiles of the longissimus dorsi muscle, liver, kidney and heart of Australian prime lambs would differ in response to supplementation with various dietary PUFA sources under a typical intensive, in-door feedlot management system. It was intended that this study would provide outcomes that can be used as guidelines for lamb producers for a better utilisation of available dietary n-3 LC-PUFA sources for enhancing lamb nutritional quality and beneficial human health outcomes
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