AFBI research concludes that glycerol from biofuel production may be a useful dietary component for broilers Biodiesel is a liquid biofuel made from vegetable oils. As a form of renewable energy the use of biodiesel decreases carbon emissions. It can be used to partially replace conventional diesel without engine modification or as 100 per cent biodiesel in engines designed for its use. Biodiesel has many advantages compared with conventional diesel and its production is increasing as EU and government regulations require fuel companies to include a proportion of biofuel in all diesel sold at the pump.

Linda Griffiths (QUB) determining the energy content of glycerol at AFBI Newforge. For every litre of biodiesel produced 0.3 litres of glycerol is produced as a by-product. Thus, in order for biodiesel production to be economically sustainable, a use is required for the un-refined glycerol. Previous research has shown that glycerol can contain as much as 75 per cent carbohydrate. In light of this, glycerol has the potential to be used as an energy source for broiler diets. However, there is a lack of information on the effect of dietary glycerol on broiler growth performance, energy utilisation and meat quality traits. A PhD programme, funded by the Home Grown Cereals Authority, has recently been initiated at Queen’s University and the Agri-Food and Biosciences Institute to investigate the use of glycerol in diets for broilers.

Research

Diets were formulated to contain 0, 3.3, 6.7 and 10 per cent glycerol as a partial replacement for wheat and were offered to broilers from seven to 28 days of age. Birds were weighed weekly and excreta were collected to determine apparent metabolisable energy (AME). On completion of the trial, a section of breast tissue was removed from each bird to determine drip loss measurements as an indication of meat quality.

AME increased linearly with increasing glycerol inclusion. However, glycerol inclusion did not affect body weight, live weight gain and feed intake. Similarly the level of glycerol inclusion did not significantly affect any growth parameters and drip loss measurements (Table 1). Feed conversion ratio (FCR) was improved with increasing glycerol inclusion and 6.7 per cent glycerol inclusion resulted in the most efficient feed conversion.

Conclusions

Apparent metabolisable energy increased linearly with increasing inclusion of glycerol, which was reflected in an improvement in FCR.

Glycerol inclusion and level did not significantly effect body weight, live weight gain, feed intake and drip loss measurements.