PHYSICAL AND MECHANICAL PROPERTIES OF HRVATICA HEN EGGS FROM FREE-RANGE RAISING AND THEIR COMPARISON WITH EGGS FROM CAGE HOUSING

Cilj ovog istraživanja bio je utvrditi fizikalna i mehanička svojstva jaja slobodno držanih kokoši hrvatica i njihova usporedba sa svojstvima jaja Hy-Line hibrida iz kaveznog uzgoja. Jaja kokoši hrvatica su bila u prosjeku 8.8% kraća, 12.7% uža i imala su 11.4% manji srednji geometrijski promjer, 24.0% manju površinu, 38.0% manji volumen i 12.4% manju debljinu ljuske u odnosu na jaja iz kaveznog uzgoja. Prosječna masa jaja kokoši hrvatica bila je 51.01 g, što je 37.4% manje nego masa jaja iz kaveznog uzgoja. S obzirom na utvrđeni indeks oblika od 72.52%, oblik jaja kokoši hrvatica može se okarakterizirati kao normalan odnosno standardan. U odnosu na jaja iz kaveza stambenih sustava, jaja kokoši hrvatica su imala jaču ljusku, njihova prosječna čvrstoća bila je 20.1% veća i potrebna je u prosjeku 9.3% veća sila za razbijanje jaja.The aim of this study was to determine physical and mechanical properties of Hrvatica hen eggs from free-range raising and their comparison with properties of Hy-Line hybrid hen eggs from cage housing. The average values of Hrvatica hen eggs length, width, geometric mean diameter, surface area and volume were found to be 55.82 mm, 40.43 mm, 45.01 mm, 6366.42 mm2 and 47835.20 mm3, respectively. According to average mass of 51.01 g, Hrvatica hen eggs can be classified as small, and according to average shape index of 72.52%, can be characterised as normal or standard. In comparison with eggs from cage housing system, Hrvatica hen eggs had stronger shell, their average firmness was 20.1% higher and required in average 9.3% greater force to rupture egg