BIOCHEMICAL ASPECTS OF BOTH THE CORTICAL BONE AND THE MEDULLARY BONE IN HENS AT DIFFERENT STAGES OF THE EGG FORMATION

10 hybrid ISA Brown hens, 50 weeks old, hold single in cages and fed with combined granulated forage, were monitored for a period of 3 weeks. They were divided into 4 groups depending on the stages of the egg formation. When 53 weeks old, the hens were sacrificed and the bones of the inferior members (femur, tibiotarsus) were prevailed and thereafter prepared to determine the content of dry matter, crude ash and minerals (calcium, phosphorous, magnesium) both for samples of the whole bone and for the samples of the cortical and medullary bone. There were no significant differences in the content of dry matter of the cortical and medullary bone samples of the femur, tibia among the individuals (p>0.05) . The content in crude ash of the femur falls significantly (p = 0.042) in the hens slaughtered 10 to 12 hours after oviposition. In the cortical bone from the femur the values of calcium, magnesium and phosphorous were not modified irrespective of the egg position in the oviduct. In the medullary bone from the femur the content in calcium and phosphorous was correlated with the egg formation stage; as for magnesium there were no significant differences during the egg formation irrespective of the stage. As for the cortical bone of the tibia of the hens from the 4 groups there are no significant differences (p>0.05) regarding the content in calcium, magnesium and phosphorous. In the medullary bone the content in calcium, magnesium and phosphorous was modified significantly depending on the position of the egg in the oviduct, and on the egg formation stage respectively.