Sixty lactating Holstein cows were fed a basal diet of corn silage, legume forages, corn, soy hulls, roasted soybean and a protein supplement. Glycerol and corn gluten feed replaced corn in the basal diet to provide 0, 5, 10 and 15 percent glycerol on a dry weight basis. Milk production, feed intake, milk composition and body condition scores did not differ among treatments. The researchers concluded that glycerol can replace up to 15 percent of the corn on a dry weight basis without adversely effecting milk production or milk composition.

Donkin, S.S., and co-workers. 2007. Performance of dairy cows fed glycerol as a primary feed ingredient. J. Animal Sci. 85: Suppl. 1: 350 (Abstract T341).

In another dairy experiment, feed intake, milk production and blood urea nitrogen were not affected by top-dressing 250 grams of dry glycerin per cow per day. Percent milk protein and fat tended to be lower with glycerin supplementation; however, yield of protein and fat was not different between treatments. A tendency for lower urine ketones and higher plasma glucose indicated the cows receiving the glycine were in a better metabolic status.

Chung, Y.H., and co-workers. 2007. Effect of feeding dry glycerin to early postpartum Holstein dairy cows on milk production and metabolic profiles. J. Animal Sci. 85: Suppl. 1: 349 (Abstract T337).

Angus-cross steers were fed diets where glycerin replaced ten percent corn in finishing diets composed of crackled corn, corn silage, DDGS and a supplement. The study resulted in a lot of data; the main effect was that animals fed the crude glycerin/glycerol supported higher average gains, reduced dry matter intake and improved feed efficiency. The research group concluded that feeding crude glycerol can improve the efficiency of cattle fed high-grain diets.

Pyatt, N.A., and co-workers. 2007. Effect of crude glycerin in finishing cattle diets. J. Animal Sci. 85: Suppl. 1: 412 (Abstract 530).

Bottom Line: Recent research has shown that up to 5-10 percent glycerol can be included in livestock and poultry diets as an energy source. Performance of these diets would be similar to diets formulated without glycerol. The decision to use glycerol in feed formulation should be based on other considerations since high levels of glycerol may alter feed handling, pellet quality, and levels of contaminants in crude glycerol. Excessive mineral (sodium and/or potassium) levels and methanol may result in production problems. Feed formulators interested in including glycerol in feed formulations should make sure the glycerol source has methanol levels below the Food and Drug Administration’s approved level of 150 parts per million in glycerol/glycerin.

Brewers Wet Grains-Composition Variability
Researchers at Rutgers University sampled daily trailer shipments of wet brewers grains from a large brewery over a twelve-month period. Samples were composited weekly and analyzed by a commercial laboratory. They reported the following data for the 48 samples: