The Effects of Thermal Manipulations During Embryogenesis of Broiler Chicks on Growth of Embryo and Skeletal Traits

Abstract

Incubation temperature is one of the important environmental factors that can induce epigenetic thermal adaptation of different physiological control systems. Thus, post hatch thermo tolerance ability of birds may be gained using these manipulations during different incubation periods. The current study was carried out to reveal the effects of temperature manipulations during early and late embryogenesis on weight of embryo and size of skeletal bilateral traits (face, wings, metatarsus, tibia, and femur) in broiler chicken embryos. One thousand commercial broiler eggs from 46 week old breeder flock were used in study. Treatments consisted of eggs incubated at 37.8 degrees C and 55% relative humidity throughout (control; DG1), heated to 36.9 degrees C and supplied 60% relative humidity for 6 hours daily from day 0 to 8 (DG2), heated to 36.9 degrees C and supplied 60% relative humidity for 6 hours daily from day 10 to 18 (DG3), heated to 41 degrees C and supplied 65% relative humidity for 3 hours daily from day 8 to 10 (DG4), and heated to 41 degrees C and supplied 65% relative humidity for 3 hours daily from day 16 to 18 (DG5). Measurements of embryo weight and bilateral traits were obtained at 20 day of incubation and at hatch (at day 21). It was determined that the live weights of embryo and chick were affected significantly by treatment; DG3 group has shown higher mean values than the other treatment groups (P<0.05). There were differences in lengths of femur, tibia and metatarsus among treatment groups at hatch. Particularly, the high incubator temperatures at the second half of incubation accelerated growth of body and bone in embryos. These consequences of the treatments performed at different temperatures and times indicate that the different metabolic shifts realized by the embryos.