Feed Fat Choice for Broilers
A University of Missouri poultry nutritionist recently wrote a paper that discussed the fat choice in broiler diets. The paper summarized two studies comparing fat sources. In the first study, seven different fat sources were included in the diet at the three percent level from hatch to seven weeks of age. The fat sources were soybean oil, yellow grease, poultry fat, tallow, vegetable-animal blend, lard and palm oil. The common diet was composed of corn, soybean meal and animal by-products. Weight gains (2.85-2.99kg) and feed efficiencies (1.77-1.87kg:kg) were not significantly (P<0.05) affected by fat source for the seven week feeding trial. Birds on all treatment performed similarly indicating differences in metabolizable energy values of the various energy sources are not critical in practical broiler diets when the total fat source is included at the three percent level; the choice of fat should be based on economics.

In the second study, soybean oil was compared to the soybean oil-animal fat blend. Seven week data indicated no significant differences in body weights (3.07-3.31kg) and minor differences in feed efficiencies (1.81-1.91kg: kg). Increased energy in the diet resulted in improved feed efficiencies at the end of the trial. Dr. Firman concluded that utilization of any of the common available fats will result in similar performance and fat additions should probably be based on economic considerations rather than criteria such as fatty acid profiles.

Firman, Jeff. 2008. Fat choice in broiler diets. Render Magazine. 12: 16-17.

Feed Use of Glycerin/Glycerol
Glycerin, or glycerol, is a by-product of biodiesel production produced by methylating a triglyceride, such as soybean oil. To produce glycerin, methanol is mixed with vegetable oil (a 10:1 ratio). The glycerin produced is a liquid product with a sweet taste; color varies from light brown to black; with a composition of 80% glycerin, 10-15% water with the rest being mainly sodium and potassium salts. Glycerin has several food, cosmetic, pharmaceutical and industrial uses. Recently the increased production of glycerin has resulted in lower prices that creates interest in using glycerin in feed formulations.

Mr. Henri de Haan reviewed the production, marketing and utilization of glycerin for a European feed publication. He cited European and US research that have established energy values for glycerin. Several research groups have established the energy content of glycerin is equal, or higher, than the energy content of corn. The energy content of glycerin will vary due to the animal species and amount included in the diet. Research with broilers, layers and pigs has shown that glycerin energy levels are lowered as the level of glycerin is increased in the diet. He indicated that glycerin can replace propylene glycol in reducing the risk of ketosis in dairy cows and is an alternative ingredient for lactose in calf milk replacers. Up to 8% can be used by feed manufacturers without effecting pellet quality. Mr. Haan summarized the review article by stating that glycerin can be included in cattle, swine and poultry feeds depending on the price of the crude glycerin (glycerol). The price will be influenced by political and economical developments.

De Haan, Henri. 2008. Glycerine; Fast energy but price sets its use. Feed Mix 16(5): 10-12.

An article in Pork Magazine cited research at Iowa State University and the University of Minnesota showing the potential use of glycerin in swine rations. The Iowa State studies demonstrated the energy value of glycerin is reduced as the level in the diet is increased. They concluded that the metabolizable energy value for pigs is 3,463 kcal/kg. The Minnesota research focused on using glycerin in lactating sow diets. They found that levels of crude glycerin of up to 9% had no significant effect on sow weight, backfat loss, litter size, weight at weaning or the wean-to-estrus interval. The authors discussed the compositional variation in glycerin lots. Of greatest concern are excessive levels of methanol, sodium chloride or potassium chloride (produced during processing). Their conclusion is that glycerin is a new ingredient that can be used in swine rations, based on its price, composition and availability.

King, Mike and Marlys Miller. 2009. Crude glycerin: The new liquid energy. Pork magazine 1:16-17.