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Over recent years, research has highlighted the importance of omega-3 fatty acids in health nutrition both for human and animals.

These are long-chain unsaturated (double bonds) fatty acids, only discovered in the 1960s. Of the ten or so omega-3 fatty acids only three are of significance and they are EPA and DHA (eicosapentaenoic and docosahexaenoic) and ALA (α-linolenic) fatty acids.

They are involved in cell division, structure, and growth in all cells from brain to muscle. To understand the role of unsaturated fatty acids, it is important to illustrate their chemical structure.

Each double bond in the carbon chain is creating an angle. The more double bonds are present in the chain and the more curved will be the molecule.

As EPA and DHA contains respectively 5 and 6 double bonds, they present a spatial conformation very different from the rectilinear saturated fatty acids as phospholipids.

Consequently, the presence of EPA and DHA in the lipidic membranes of the cells will give some properties regarding membranes fluidity and permeability, especially in brain and reproductive systems but as well in muscles and even retina.

The brain has the highest concentration: of the 60 % lipid in the brain, 20 % are DHA and 14 % arachidonic acid, an omega-6 fatty acid (cf figure below).

Although the pig’s brain is much smaller than that in the human, sows end up exporting a significant amount of DHA for piglet development.

A deficiency in DHA will impact overall piglet quality during foetal development and early growth. A recent survey has shown that pre-weaning mortality in UK can reach 15 % in highly prolific herds and that more than 50 % of these piglets are “crushed healthy”. The higher the prolificacy of the sow, the higher will be the requirement for DHA to ensure agile, alert young piglets. Improved piglet quality is critical for good performance in the fattening period. The addition of DHA to sow feed brings measurable improvements in piglet productivity.

Mammals are unable to synthesize the essential omega−3 fatty acid that can only be obtained through diet. However, they can use ALA, when available, to form EPA and DHA, by creating additional double bonds along its carbon chain (desaturation) and extending it (elongation). Namely, ALA (18 carbons and 3 double bonds) is used to make EPA (20 carbons and 5 double bonds), which is then used to make DHA (22 carbons and 6 double bonds).

But the Omega-3 fatty acids are not the only one to use the desaturase enzyme to be processed, Omega-6 fatty acids and namely the linoleic acid. The difference between the Omega-3 and Omega-6 family comes from the position of the double bond (in the 3rd position for the Omega-3 and 6th position for the Omega-6).

To ensure that sufficient ALA and EPA can be processed in DHA, we need to avoid an excess of Omega-6 by ensuring an optimal ratio of Omega-6 / Omega-3 in the diet.

Study suggests that our ancestors consumed omega-6 and omega-3 fats in a ratio of roughly 1:1. At the onset of the industrial revolution (about 140 years ago), there was a marked shift in the ratio of n-6 to n-3 fatty acids in the human and animal dietary practices. On one side, soya / corn, both very high in Omega 6, became the main source of protein and energy in most feed in the world. In parallel, we are diminishing / removing fish and animal-based ingredients from animal diet. These trends led the ratio Omega-6 / Omega-3 ratio to increase up to 25 whereas we consider that the physiological optimum should be around 3 to 4.

That ratio can be easily managed by animal feed nutritionists by adding a constraint on the Omega-6 / Omega-3 ratio in the formulation software. It may come with an extra cost but should be compensated by an improvement of reproductive performance on sows and boars but as well a better agility and growth of piglets from early life to slaughter.

Marine algae and phytoplankton are primary sources of omega−3 fatty acids. DHA and EPA accumulate in fish that eat these algae. Common sources of plant oils containing ALA include walnuts, edible seeds, and linseeds, while sources of EPA and DHA include fish and fish oils, as well as algae oil. The problem of fish oil is the high variability of its EPA and DHA content. Every batch of fish oil needs to be analyzed before the diet can be reformulated. Moreover, without proper precautions, unsaturated fatty acids like ALA, DHA and EPA can be easily ‘deactivated’ by oxidation, especially in tropical conditions which bring rancidity to the diet, reduction of feed palatability and even an oxidative stress to the animals. It is essential to select the most adapted source of ALA, EPA and DHA to maximize the chances for the animals to stock them up.

The strategy for increasing Omega 6 / Omega 3 ratio should primarily focus on the improvement of the reproduction cycle. Studies show that piglets coming from sows fed from proper balance of Omega 3 will demonstrate better growth performance from birth to fattening. The piglets are born with a higher stock of EPA and DHA that will support their development until slaughterhouse.

The fertility cycle in pigs starts with the production of a wave of follicles, about 25 per wave for sows. For good piglet production, all these follicles need to be strong and active. As they are cells, EPA and DHA are needed to make these cells strong and active. Once they reach a certain size, they break through the ovary walls to form an ulcer, the corpus lutea. This releases progesterone that manifests itself as the sow being on heat. It is important that this secretion does not go on longer than three days, otherwise it will not allow conception to take place. So, the ulcer must heal quickly, and EPA and DHA facilitate this healing. After fertilisation, the embryos float around in the uterus for about three weeks before implantation. During this time, they must stimulate their own food supply by making contact with the uterus wall. Failure to do this will cause them to die of starvation, hence the need for active follicles. When contact with the wall has been made, it is important that the food supply is available, and this is a function of the hormone oestrogen (oestradiol) that is EPA and DHA dependent. If ALA, EPA and DHA fatty acids are short, then food supply will be short, and embryos will die.

In practise, the consequences of insufficient EPA and DHA are:

• Sows returning to service

• Fewer than potential piglets born

• Weak piglets

• Variable piglet weights

• Slower growth rates

• More subject to disease

• More piglet aggression

• More piglet crushing

Consequently, feeding Omega-3 to sows before farrowing would contribute to the foetus development in order to offer to the new-born piglets better chances of survival and development during their life at the farm.


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