Review on docosahexaenoic acid in poultry and swine nutrition: Consequence of enriched animal products on performance and health characteristics

Abstract

Omega-3 polyunsaturated fatty acids (n-3 PUFA) are linked to a variety of health benefits against human disorders and disease. However, the typical western diet is generally low in n-3 PUFA and high in n-6 PUFA, suggesting that the recommended intake of these essential fatty acids is seldom achieved. Therefore, dietary enrichment of animal meat and eggs with n-3 PUFA could help increase consumption of these fatty acids. Fish oils and microalgae (MA) are rich sources of long chain n-3 PUFA, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Feeding these marine products has been shown to increase DHA content of tissues and yolk, however, this may also lead to an increased requirement for anti-oxidants to prevent oxidative deterioration and associated negative sensory attributes. Nonetheless, increased DHA has been linked to promising results in animal growth, fertility, immunity and bone strength in both pigs and poultry. These findings suggest that feeding DHA-rich ingredients to mono-gastric can enrich human diets as well as providing additional benefits to the animal.

Keywords: Anti-oxidant; DHA; Microalgae; Performance.

Fig. 1

Polyunsaturated fatty acid (PUFA) metabolic pathway. Animals are unable to endogenously synthesise linoleic (LA) or α-linolenic acid (LNA) and therefore these essential fatty acids must be consumed from dietary sources. Endogenous desaturases and elongases are responsible for conversion of LA and LNA to the key metabolites: arachidonic acid (AA), docosapentaenoic acid (DPA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Desaturase enzymes are the same for both omega-3 and omega-6 pathways, and therefore DHA production may be limited when the LA to LNA ratio of the diet is high.

Fig. 2

Schematic of lipid peroxidation and scavenging reactions. Polyunsaturated fatty acids of the lipid membrane are highly susceptible to free radical damage. Reactive oxygen species, such as OH⁻, take electrons from the lipid producing water and an alkyl radical. This fatty acid radical reacts readily with oxygen to generate a peroxyl radical. Vitamin E (α-TOH) donates an electron to the peroxyl radical to create a lipid peroxide, which is then further detoxified by glutathione peroxidase (GSHP) to produce a lipid alcohol and water. Glutathione reductase (GSHR) subsequently reduces glutathione disulphide (GSSG), consuming nicotinamide adenine dinucleotide phosphate (NADPH) and producing glutathione (GSH), which is then cycled back to GSHP.