Rearing pigs at pasture with a diverse range of grasses in the sward could offer a valuable income stream for producers because a study has identified that it boosts their meat with fatty acids beneficial to human health.

An on-farm research trial in Wales showed a significant increase in a-Linolenic acid (ALA) in the meat from gilts kept on leys of ryegrass, clover, sainfoin, chicory, kale and forage rape for three months before slaughter and fed 2kg/day/head of concentrates compared to those reared only on the same amount of concentrates on bare land.

The study was run by Menter Moch Cymru and Farming Connect at Forest Coalpit Farm, Abergavenny, where Kyle Holford and Lauren Smith run an outdoor farrow to finish herd of Large Black x Duroc pigs.

Only gilts were used for the trial so that the dataset could not be influenced by gender differences, and they were all progeny from the same boar.

Pigs were paired and split at random into the allocated treatment groups at 92 days old.

Nine were reared in a grass paddock with standard feed, firstly a grower spec ration and switching to a finishing spec ration at 120 days, and 10 gilts in a bare paddock with the same feed.

The volume of feed was restricted to encourage grass intakes in the pigs on the grassland.

The pigs were slaughtered on the same day when they were around 93kg.

Tests to establish the fatty acid profile of meat from each group were carried out in the laboratory at the Food Technology Centre, Llangefni, on two loin steaks from each animal.

Caroline Mitchell, director of the food quality management consultancy firm FQM Global, who oversaw the project, says the meat from the pigs with access to forage had significantly higher levels of Palmitoleic acid (a probability (p) value of 0.0092), Stearic acid (p value of 0.0460), and ALA (p value of 0.0008); a p-value of less than 0.05 is statistically significant.

This analysis showed that ALA was the fatty acid most affected by the addition of forage.

As pigs are unable to synthesise ALA, the significant difference between treatment groups is a direct result of the addition of forage to the diet, says Ms Mitchell.

There are known to be multiple benefits to humans from eating products containing ALA, including preventing heart attacks, lowering high blood pressure and cholesterol and reversing hardening in blood vessels.

Studies have already shown that through manipulating feed, such as adding oils from fish, plants or seeds, it is possible to make the meat of pigs a functional food as a result of its omega 3 and omega 6 content.

“It would be interesting to see if different forage leys can manipulate the functionality of the meat further,’’ says Ms Mitchell.

At 19, the number of gilts in the study was relatively small so, to draw further conclusions on the influence of forage on meat quality, a larger dataset would be required, she admits.

This study was the first of its kind and the results could be a catalyst for further research, Ms Mitchell adds.

But the results to date could allow Forest Coalpit Farm to add value by offering a unique selling point.

Mr Holford and Ms Smith say meat quality is central to their business - they butcher and sell their produce directly to customers in pork boxes and also supply restaurants and butchers.

Breed, management and diet are all factors that influence this but the project had quantified the benefits of forage too, says Mr Holford.

“It’s been fascinating to look at the relationship between feeding pigs forage and the effect it has on meat and fat quality, to find out that it effects the fat and makes a healthier product is just phenomenal,’’ he says.

“This just shows there is even more benefit to raising pigs outside on grass. Other producers can use this to quantify it and add value to an already great product.’’

The chemical analysis of the pork could be useful for advertising potential health benefits, he adds.