EFFECT OFINTERACTION BETWEEN FEED RESTRICTION AND DIETARY ENERGY LEVELS ON PRODUCTIVE, PHYSIOLOGICAL, IMMUNOLOGICAL PERFORMANCE AND ECONOMIC EFFICIENCY OF TWO STRAINS OF LAYING HENS.

This study was conducted to determine the effect of interaction between feed restriction and dietary energy levels on productive, physiological and immunological performance as well as economic efficiency of Matrouh and Silver Montazah chickens (females and males).A total number of 240 females and 24 males 24 weeks old from each of Matrouh (MAT) and Silver Montazah (SM) layer strains (120 females and 12 males from each strain) were used, Birds of each strain were randomly divided into 4 equal groups with 3 replicates each of 10 females and one male. The first and second groups fed diet contained 2800 and 2600 kcal ME /kg diet, respectively at a rate of 120g/ hen/day. The third and fourth groups fed diet contained 2800 and 2600 kcal ME /kg diet, respectively at a rate of 100g/ hen/day. Theobtained results showed that Silver Montazah hens recorded higher values for egg production%, egg weight,egg mass and feed efficiency, hatchability % and post hatch chick weight as well as T3, LH and FSH hormones as compared  with Matrouh (MAT) hens.Reducing the amount of feed provided to hens (100 g/hen/ day) significantly improved feed efficiency and increased blood levels of T3 and LH hormones, fertility and hatchability percentages, chick weight at hatch and weight of abdominal fat were significantly decreased. the best results of egg production%, egg weight and egg mass, as well as chick weight at hatch, fertility and hatchability percentages were recorded for SM hens which received diet containing 2800 kcal ME at a rate of 120g/hen/day, the lowest results were recorded for MAT hens which fed diet contained 2600 kcal ME at a rate of 100g /hen/day. However, the best feed efficiency was recorded for hens of both strains which received diet contained 2800 kcal at rate of 100 g/hen/day. T3 and LH hormones, chick weight at hatch as well as fertility and hatchability percentages were increased for SM hens either those received low or high dietary energy content at a rate of 120 or 100g/hen/day comparing with MAT hens which received the same experimental diets. Semen quality traits were found to be improved for SM cocks under the two levels of energy and feeding.The highest economic efficiency values were exhibited by SM hens fed high or low dietary energy levels at a rate of 100 g / hen / day. It could be concluded that the best feed efficiency and economic efficiency were recorded for hens of both strains which received diet contained 2800 kcal at rate of 100 g / hen/ day.