Effect of crude glycerin level in the diet of laying hens on egg performance and nutrient utilization

An experiment was conducted with 72 Bovans Brown laying hens to determine the effect of dietary crude glycerin on laying performance; egg quality; retention of N, Ca, and P; and metabolizability of energy. The dietary treatments consisted of a control corn-soybean diet containing 6% corn starch (17% CP, 2,775 kcal/kg of AME(n), 0.81% lysine, 0.36% methionine, 3.60% Ca, and 0.37% available P) and 3 experimental diets. In the experimental diets, 2, 4, or 6% crude glycerin (a coproduct of commercial biodiesel production from rapeseed) was substituted for corn starch. During the experimental period (28 to 53 wk of hen age), the dietary level of glycerin had no significant effects on performance indices [i.e., egg production (mean value of all 4 dietary treatments was 95.6%), egg weight (60.4 g), daily egg mass (57.8 g/hen), daily feed consumption (121 g/hen), and feed conversion (0.477 g of egg mass/g of feed consumed)]. No significant treatment effects were found for egg quality parameters (albumen height, Haugh units, yolk color and thickness, density and breaking strength of eggshell), excretion and retention of N, Ca and P, or metabolizability of energy. Linear regression analysis revealed that the AME(n) value of crude glycerol was 3,970 kcal/kg (as-is basis). The results of this study demonstrated that crude glycerin may be incorporated to a level of 6% in the diet of laying hens without any detrimental effect on egg performance, egg quality, nutrient retention, and metabolizability of energy.