ABSTRACT Layer hybrids are more superior in the egg yield than pure breeds. But this superiority causes some problems in the bones during the production period. There are a lot of differences among genotypes in the production period that have been examined extensively, however, the differences throughout incubation period aren’t known yet. Thus, the objective of this study was to evaluate the differences in femur properties of pure breed and layer hybrid embryos during the incubation period. A total of 354 fresh hatching eggs were used from one hybrid (Lohman White) and two pure breeds (Denizli & Gerze). The eggs were incubated. Hatching eggs from each genotype at the beginning of embryonic days (E) 19 and E21 were examined. At these embryonic ages, 12 eggs were selected from each genotype. The eggs were opened and embryos were sacrificed by cervical dislocation. Both femurs were dissected from each embryo and then structure, mineral composition and mechanical properties of femur were determined. The genotype affected the length, width and Zn level in the femur of embryos. Weight, length, width, load of yield and ultimate, ash and all examined minerals increased with embryonic development. These results showed that some femur properties of embryos were influenced by the genotype and layer hybrid embryos are beginning to be advantageous in terms of Zn level in the femur at E21. This study leads to better understanding femur development during the incubation period in layer hybrid and pure breeds.

ABSTRACT Pure breeds are important due to the fact that they adapt well to poor husbandry conditions. However, gene expression of digestive enzymes and nutrient transporters of pure breeds and layer hybrids have not been studied yet. Therefore, this study was directed to detect the gene expression of digestive enzymes and nutrient transporters in the yolk sac membrane and small intestine of the embryos in layer hybrid and pure breeds. A total of 354 hatching eggs were collected from 29 wk old Denizli, Gerze and Lohman White (LW) breeder flocks. Twelve eggs from each genotype were selected at embryonic day 19 (E19) and day 21 (E21). APN, SI, PepT1, EAAT3, CAT1, B0AT, SGLT1 and GLUT5 mRNA expressions were evaluated in the yolk sac membrane (YSM) and small intestine of the embryos from different genotypes. Expressions of APN and EAAT3 in the small intestine of Denizli embryo were upregulated from E19 to E21. B0AT, PepT1 and SGLT1 expressions were upregulated in the small intestine of pure breed and layer hybrid embryos with increasing embryonic age. SI expression in the small intestine of the LW embryos was upregulated from E19 to E21. APN, B0AT and EAAT3 expressions in the YSM of Denizli embryos were dowregulated from E19 to E21. EAAT3 and SGLT1 expressions in the YSM of Gerze embryos were upregulated at E21 and compared to E19. Taken together, our results indicate that genotype and embryonic age influenced the expression of digestive enzymes and nutrient transporter genes in the small intestine and YSM of embryos.