Nutritional and feeding value of crude glycerin for poultry. 1. Nutritional value of crude glycerin

Glycerin is the main by-product of biodiesel production and it has been speculated that it may be a good energy source in poultry diets. However, knowledge is limited on the nutritional value of crude glycerin. Thus, the objective of this study was to determine the nutritional and chemical characteristics of various glycerin samples from diverse production facilities. Seven samples of crude glycerin from an array of biodiesel producers were analyzed for gross energy and TMEn. Ten crude glycerin samples were analyzed for glycerol, methanol, nutritional, and mineral composition. Considerable variation was found in the composition of the crude glycerin samples. The gross energy ranged from 3,337 to 6,742 kcal/kg, with a mean of 4,648 kcal/kg, and TMEn ranged from 2,950 to 6,711 kcal/kg, with a mean of 4,206 kcal/kg. Mean concentration values for glycerol, methanol, moisture, fat, salt, and ash were 63.7, 1.33, 18.2, 8.1, 2.19, and 4.35%, respectively. Phosphorus was the highest mineral component, with an average of 0.1% in the crude glycerin samples, and the average calcium, potassium, copper, zinc, iron, magnesium, and manganese levels were 328, 2,090, 3.20, 5.21, 18.6, 43.6, and 1.26 ppm, respectively. The range in glycerol, methanol, moisture, fat, salt, and potassium levels were from 34.2 to 86.1%, from 0.01 to 3.10%, from 7.85 to 34.9%, from 0.01 to 30.0%, from 0.01 to 4.21%, and from 120 to 11,200 ppm, respectively. Based on the variation observed among samples, we suggest that confirmatory analyses be conducted before using any crude glycerin product in poultry diets.