Evaluation of two soybean soapstocks in egg production and quality in Bovans hens

Abstract

Crude soybean oil (CSO) is used to increase metabolizable energy (ME) content in diets for laying hens. Also used in human food, its price is consequently high. Oil soapstocks are byproducts of the oil extraction process and therefore cost less. An evaluation was done of the effect of two soybean soapstocks (SS) on egg production, quality and lipid composition, and the cost of 1 kilogram of eggs. Soapstock ME and lipid composition were quantified. An experiment was done using 240 hens in six treatments, with five replicates and eight hens per replicate. Diets were formulated using CSO, or one of the soapstocks, at 2 or 4% concentrations. The evaluated productive variables were feed intake, feed conversion, egg weight, egg mass, laying percentage and egg quality parameters. Egg lipid composition was described and the cost per one kilogram calculated. Replacement of CSO with the soapstocks did not affect poultry production variables (P>0.05), but did improve Haugh unit values (P<0.05). Egg fatty acids composition changed in response to oil composition (P<0.05), and inclusion concentration affected the levels of specific fatty acids. Use of the soapstocks resulted in a lower cost per kilogram of eggs than with CSO (P<0.05). Substitution of crude soy oil with the evaluated soapstocks had no effect on productive variables, improved egg quality and lowered overall feed costs.