Direktne metode za određivanje čvrstoće ljuske jaja

Abstract

During the manipulation of hen eggs from the farm to the consumer due to action of external forces and weak mechanical strength of shell, the eggs break. The goal of egg producers is to reduce losses when breaking eggs during the production and placement, and thus increase revenues. Each egg can be damaged by external forces whose values are greater than maximum strength of the egg shell. Direct and indirect methods are used to determine the quality of eggs and shell strength. By direct methods, strength of the shell can be determined on the basis of puncture force measurements, impact forces, quasi-static compression forces and free fall forces on a known surface. In our research, a device was constructed for the realization of experiment and a direct method for determining strength of eggs was applied on the basis of measured breaking force of the shell. The device for measuring strength of eggs by the direct method of puncture eggshell was constructed and applied at the Faculty of Technical Sciences and the Faculty of Agronomy in Čačak. Class "M" hen eggs produced on the "Grbović" farm in the vicinity of Čačak were used in the research. The laying hens are a 41-week-old Isa Brown hybrid. During the research, physical characteristics of hen eggs were determined: length, width, index of shape and weight of eggs, as well as weight of the shell, share of the shell in the total mass of eggs, thickness and puncture force of the shell. The results of research show that the length of egg is 57.00 mm, width 44.59 mm with a coefficient of variation from 2.7 to 1.4%. The thickness of egg shell is on average 0.39 mm, in range from 0.377 to 0.416 mm. The share of shell is 10.54% of average weight of eggs (62.43 g). The quality of the tested eggs was quite uniform because the puncture force of egg shell ranged from 20.35 to 23.97 N. The research results are important for cage construction, design of egg collection equipment, design of egg packaging, and applicable in selection for obtaining new genotypes of laying hens with increased resistance to egg breaking.