Effects of Supplementing Different Linoleic to α-Linolenic Acid Ratios and Vitamin A on Performance and Egg Quality Characteristics of Laying Hens during Summer Months

In present feeding trial, responses of laying hens, reared at high ambient temperature, to various dietary ratios of linoleic acid (LNA) to α-linolenic acid (ALA) and vitamin A levels for performance and egg characteristics were observed. 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 diet. The diets were fed ad libitum in a 6×2 factorial Completely Randomized Design that continued from 40 to 52 weeks of age. Standard managemental and housing conditions were provided to all hens. Feed intake, weight gain, egg production and egg quality traits were recorded during the trial on weekly basis. The results showed that decreasing dietary LNA to ALA ratio diet negatively affected (P<0.05) the body weight gain and yolk percent. While, feed intake, hen-day and hen-housed egg production and shell quality remained unaffected (P>0.05) by dietary treatments, with the exception of FCR per kg egg mass, egg weight and egg-shell thickness which were improved significantly (P<0.05) in hens fed on diets with lower LNA: ALA. Although dietary ratio of LNA to ALA of 4: 1 or less could produce eggs by hens with high 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, but, on overall-basis, performance of laying hens was similar among all LNA to ALA ratio in the diet.