Biodiesel production may be the solution to providing a cheap source of energy in pig diets, research at the Agri-Food and Biosciences Institute, Northern Ireland, has shown.

With biodiesel production predicted to meet 5% of total energy production in the UK, there will be no shortage of the by-product glycerol, a possible useful source of energy in pig diets, says AFBIs’ Elizabeth McCann.

“With a digestible energy content of 14MJ/kg, crude glycerol would make an excellent energy source for pigs and because it can be used in its crude form, it could possibly replace some of the more expensive diet components.

“However, because past research has found glycerol to reduce performance, but increase meat quality, we wanted to look at how inclusion levels affected performance and meat quality,” said Dr McCann.

Wheat was replaced with glycerol and fed at levels of 0, 40, 80 or 120g/kg glycerol. The results showed the higher the glycerol inclusion the lower average daily gain, 905g for pigs fed 120g a day, compared with 1031g a day for those fed no glycerol.

“Although feed intake and FCR was not affected by glycerol, FCR did become less efficient as glycerol inclusion increased and this is possibly because the digestible energy content of glycerol is lower than wheat. More work needs to be done, but carcass quality was not affected by glycerol,” she said.