Omega-3 Enriched Pork
The health benefits of polyunsaturated, omega-3 (ω3) fatty acids in diets for humans have been well established in numerous scientific studies. Among the omega-3 fatty acids, eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) are more beneficial to humans than alpha-linolenic acid (ALA). Pork products enriched with omega-3 fatty acids have not gained a large market presence, due largely to variability in the omega-3 fatty acid content and the negative impact of unsaturated fats on various aspects of pork quality.
This is especially a concern in pigs fed corn-based diets due to the relatively high unsaturated fat content of corn. Typically, to generate omega-3 enriched pork products, omega-3 fatty acids usually ALA from flaxseed are fed for a short period prior to slaughter resulting in the incorporation of omega-3 fatty acids preferentially in back fat rather than intra- and inter-muscular fat. An alternative approach, feeding fish oils high in EPA and DHA, unfortunately results in pork with a distinct fishy flavour and after-taste.
Research has demonstrated that in humans, females and the young can convert ALA to EPA and DHA, however little is know about this conversion effect in pigs. If present in pigs, this conversion process may be an important mechanism to produce pork that is relatively high in long chain omega-3 fatty acids.
A recent research study by Héctor Martínez-Ramírez and Dr Kees de Lange looked at determining the rate of retention and apparent conversion of ALA to EPA, DPA and DHA in growing gilts. Over a 30-day period, they fed a corn-wheat-soybean meal based diet with 10 per cent ground flaxseed to growing gilts between 27.7 kg and 45.7 kg. Chemical body composition was determined at initial, intermediate and final body weight from four, six and five pigs, respectively.
They found that whole body content of omega-3 and omega-6 fatty acids increased linearly over time. However, the efficiency of retention of ALA declined numerically between the two periods measured (day 0 to 15 and day 15 to 30). The conversion of ALA to EPA and DPA did not change over time.
An interesting outcome of the study was that pigs appear unique in that they store the omega-3 fatty acid eicosatrienoic acid (ETE), an intermediate between ALA and EPA, which should be explored further.
The take home message for producers and consumers is that the term 'omega-3-enriched' pork can be misleading. More important than the total omega-3 content is the concentration of the specific health promoting omega-3 fatty acids EPA, DPA and DHA and their distribution in lean and fat tissues. Therefore, while feeding flaxseed did lead to modest increases in long chain omega-3 fatty acids the ability of the pig to convert ALA to EPA, DPA and DHA declines over time and may not produce the desired enrichment level.
