Low and High Erucic Acid Rapeseed Oils in Rations for Laying Hens

The effects of including 10% of different types of rapeseed oil in rations for White Leghorn pullets nearing peak of production on energy intake, egg production, egg weight, lipid content of egg yolk and distribution of fatty acids in egg yolk lipids were studied. Regular rapeseed oil, containing a fairly high level of erucic acid (21.4%) and three rapeseed oils of low erucic acid content namely: Canbra, hydrogenated Canbra and Span were used in the study which covered a 14 day pre-treatment and a 28 day treatment period. Daily energy intake increased in all groups from pre-treatment to treatment periods. It was highest in the groups fed the control ration and the ration containing 10% soybean oil. In these two groups egg production and egg weight were increased during the treatment period. Hens receiving rations containing the low erucic oils produced heavier eggs in the treatment period but the increase in egg weight was significantly smaller than in those groups fed the control or soybean oil containing diet. Feeding regular rapeseed oil led to a marked decrease in egg weight. In this group a tendency for decreasing yolk weight occurred whereas for the soybean oil fed group the reverse was true. Although the total lipid content of egg yolk remained constant the fatty acid pattern changed significantly while feeding the oil-containing diets. Oleic levels of egg yolk fat were higher in eggs produced by hens fed the rapeseed oil containing diets than in eggs from hens fed the control or soybean oil containing diet. When diets containing rapeseed oils were fed the amount of gadoleic acid in egg yolk lipids was increased whereas the contents of palmitic and stearic acid were decreased markedly. No substantial amounts of erucic acid were found in the eggs.