Effects of supplementing various linoleic to α-linolenic acid ratios and vitamin A on production performance and egg characteristics of laying hens during summer months

In the present feeding trial, responses of laying hens, kept at high ambient temperature, to various dietary ratios of linoleic acid (LNA) to α-linolenic acid (ALA) and vitamin A levels on performance and egg characteristics were evaluated. A total of 360, 40-wk-old, Leghorn laying hens were fed on diets with various combinations of canola oil and linseed oil to achieve LNA to ALA dietary ratios of 20:1, 10:1, 4:1, 2:1, 1:1 and 1:2, each supplemented with 3000 IU or 10000 IU vitamin A/kg of diet. The diets were fed in a 6×2 factorial Completely Randomized Design that continued for 12 weeks. Feed intake, weight gain, egg production and egg quality traits were recorded during the trial. Decreasing dietary LNA to ALA ratio in the diet affected negatively (P<0.05) on body weight gain and yolk percentage in laying hens. While, feed intake, hen-day and hen-housed egg production, feed conversion ratio (FCR) per dozen of eggs and shell quality remained unaffected (P>0.05) by dietary treatments, with the exception of FCR per kg eggs, egg weight and egg-shell thickness which responded significantly (P<0.05) to various dietary treatments. Although the dietary ratio of LNA to ALA of 4:1 or less could produce eggs by the hens with desirable quantities of n-6 and n-3 poly unsaturated fatty acids – that are characteristics of functional diets – the performance of laying hens in terms of body weight gain and egg-yolk percentage was slightly compromised.