Nutritional Evaluation of Rapeseed Oils and Rapeseed Soapstocks for Laying Hens

Abstract

An experiment was conducted to determine the effect of regular Brassica napus, Brassica campestris and low erucic acid (Oro variety) rapeseed oils (RSO) on the performance of laying hens. Feed grade tallow and corn oil were used as controls. The response was measured in terms of egg production, egg size, hatchability, and fatty acid and cholesterol levels in egg yolk. The metabolizable energy content of the oils was also determined. When included in the diets of laying hens at levels of 10 and 20% B. napus and B. campestris RSO exerted a depressing effect on egg production, egg weight, yolk weight and hatchability as compared to the performance of hens on tallow or corn oil. In contrast, the use of low erucic acid rapeseed oil exerted no detrimental effects on reproductive performance thus suggesting that erucic acid is the main factor responsible for the deleterious effects.At the 10% level of incorporation, B. napus and B. campestris RSO were well utilized by laying hens. Refined B. napus and B. campestris RSO were lower in metabolizable energy than the corresponding crude oils. The total lipid content of the yolk was not influenced by the type or level of dietary fat. Addition of various rapeseed oils to the basal diet altered the fatty acid composition of egg yolk. The average erucic acid content of yolks of hens fed 10 and 20% B. napus and B. campestris RSO was 0.6% whereas birds fed low erucic acid rapeseed oil deposited 0.2% erucic acid in the yolk fat. The cholesterol content of the egg yolk of birds fed rapeseed oil was higher than that of birds fed the no-fat basal diet but lower than yolks from corn oil-fed birds.