Improving eggshell quality by replacement of pulverised limestone by granular limestone in the hen diet

Abstract

Eggshell quality was studied in a total of 108 Hissex hens from 58 to 62 weeks of age. All hens received a basal diet of the same composition. The differences between the three equal groups were in the replacement percent of fine pulverised limestone by granular limestone, of larger particle size. The first group (control) received the basal diet with only pulverised limestone as a calcium supplement. In the diet of the second group, 60 % of the pulverised limestone was replaced with granular limestone and in the third group percent 80 %. Significantly higher breaking force (3.6 kg), shell mass (8.2 g), shell thickness (36 0.01 mm) and lower deformation (20.4 μ) were found for eggs from the third group of hens than for eggs from the first group (3.4 kg; 8.0 g; 35 × 0.01 mm; 21.4 μ; respectively). Also, these eggshell characteristics were more favourable in the second group than in the first group, but the difference was significant (p<0.05) only for breaking force (3.5 kg versus 3.4 kg). The results obtained in our investigation showed some possibilities of eggshell quality improvement using limestone of larger particle size as a Ca supplemente in the hen diet. Replacing 60-80 % of pulverised limestone by larger particle size limestone had positive effects on eggshell quality.