Effects of hens feeding on eggshell properties and their interrelationship

Abstract

Eggshell quality was studied in three groups of Issa brown hens, of 73 to 78 weeks of age. The group 1 received a basal diet with 3.8 % of Ca and 0.35% of available P, in which pulverised limestone (particle size 0,02 mm) was the main source of Ca. The other two groups of hens were fed the diet of the same composition, but differing in the particle size of supplemented limestone. In the groups 2 and 3, 60% of the pulverised limestone was substituted with a granular form, particle size 1.10-1.40 mm, i.e. 1.42-2.80 mm, respectively. Eggs for examination were collected every day, at three periods of time: 7-9 a.m., 11 a.m. - 1 p.m. and 3-5 p.m. There were significant effects of particle size and oviposition time on eggshell quality. Egg mass and shell deformation decreased, while shell breaking force, thickness and mass increased with the increased oviposition time. At the afternoon period of laying, significantly higher (p (lt) 0.05) breaking force (5.0 kg) and lower shell deformation (21.9 µ) were obtained in eggs of hens fed the diet incorporated with the granular form of limestone (particle size 1.10-1.40 mm) than eggs of hens fed only pulverised limestone. Correlations between shell deformation and breaking force were high and negative. Correlations between these two parameters and shell thickness were medium weak.

Kvalitet ljuske jaja je ispitivan kod tri grupe nosilja u periodu između 73 i 78 nedelje uzrasta. Grupe su hranjene smešom istog hemijskog sastava, ali su se razlikovale u veličini čestica izvora kalcijuma. Prva grupa je kao izvor kalcijuma u smeši dobijala sitno mleveni krečnjak - kredu, veličine čestica (lt) 0,02 mm. Kod druge grupe je 60 % krede bilo zamenjeno granuliranim mermerom, veličine čestica između 1,1 i 1,4 mm, dok je kod treće grupe 60 % krede bilo zamenjeno granuliranim mermerom, veličine čestica između 1,42 i 2,80 mm. Jaja za analizu su sakupljana svakodnevno a praćene su sledeće osobine: masa jaja, deformacija, sila loma, masa i debljina ljuske. Ustanovljeno je da jaja snešena popodne, druga grupa nosilja, imaju značajno veću (p (lt) 0,05) silu loma ljuske (5,0 kg) i manju deformaciju (21,9 µ) u odnosu na jaja nosilja ostale dve grupe. Korelacionom analizom je kod svih grupa nosilja, ustanovljeno postojanje srednje jake povezanosti (r = - 0,57 do - 0,63) sa negativnim predznakom između sile loma ljuske i deformacije. Međusobni odnosi ostalih osobina su se kretali u granicama slabe korelacije.