Effects of diets containing different levels of energy and protein on egg production performance and hatchability in Sepahan native breeder hens

During many years, with the breeding operations on native hens of Sepahan, growth rate, age of sexual maturity, egg production, egg weight and many other traits of their productive performance have been improved. Estimation of nutritional requirements, especially metabolisable energy and crude protein, is necessary to achieve high fertility and hatchability and produce day-old chicks with appropriate quality. This study was conducted to investigate the effect of different dietary energy and protein on productive performance and egg quality characteristics of the improved indigenous hens in 42-53 weeks of age (during 3 periods of 28 days). Totally, 180 Sepahan hens were assigned to a 3 × 2 factorial arrangements in a completely randomized. Factor 1 was different levels of metabolizable energy (2400, 2550 and 2700 kcal/kg), and factor 2 was levels of crude protein (14 and 16%). Data were collected for feed intake, egg production, egg weight, feed to egg conversion ratio, shell strength, shell thickness, shell weight, percentage of shell weight to egg weight, yolk color index, percentage of yolk weight to egg weight and Hough unit. In addition, during the experimental period, during three stages after artificial insemination, the eggs of Isfahan native breeder hens were collected and after numbering and grading, they were grouped and separated according to the treatment and repetition of the device. Incubators were transferred. At the end of the incubation period, the number of hatched chicks from each replication was counted and group weighing was performed. The components studied at this stage of the experiment also included fertility efficiency, hatchability, day-old chick weight and percentage of chick weight to hatchable eggs. According to the results of the present experiment, in the whole experimental period, feed intake, egg weight and egg production were not affected by experimental treatments (P<0.05). Egg mass weight in chickens fed diets containing 2550 kcal was significantly higher than chickens fed diets containing 2400 kcal (P <0.05) and feed-to-egg conversion ratio in native hens, fed diets containing 2550 kcal was lower than 2400 kcal (P <0.05). The highest egg shell strength (3.4 kg/cm2) was in diets containing 2700 kcal energy and 14% crude protein and the lowest (3.02 kg/cm2) was in diets containing 2400 kcal energy and 14% crude protein (P<0.05). By increasing crude energy levels, the color of egg yolk also increased (P <0.05). Increasing the level of crude protein in the diet decreased Hough units of eggs (P <0.05). The highest rate of fertility and hatchability of hatchable eggs was obtained in treatments containing 2550 kcal of energy (P<0.05). Experimental treatments had no significant effect on the weight of day-old chicks (g) and the ratio of chicken weight to the weight of hatchable eggs. However, fertility (percentage) and hatchability rates of fertile eggs (percentage) were affected by different energy levels (P <0.05), so that the highest fertility rate was in treatments received 2550 kcal ME/kg of diets. Different levels of crude protein and energy and protein interactions had no significant effects on these traits. Embryo mortalities in the first and second weeks of the incubation period (percentage) were not affected by experimental treatments, but embryo mortalities in the third week and in the whole incubation period were affected by the interaction of energy levels and crude protein in the diet (P<0.05). In general, based on the results obtained under the conditions of this study, it seems that the diet containing 2550 kcal metabolisable energy and 14% protein is appropriate for feeding to Isfahan native breeder hens during the laying period.