SEASONAL VARIATION OF EGG SIZE AND EGGSHELL QUALITY CHARACTERISTICS IN LAYERS
Nedeljka Nikolova , Dragoslav Kocevski , Gjoko Bunevski , Vladimir Djabirski , Vlado Vukovich , Kocho Porchu , Danail Shutevski
Institute of Animal Biotechnology, Faculty of Agricultural Science and Food, “Ss. Cyril and Methodius” University in Skopje, Republic of Macedonia
nikolova13@gmail.com
An analysis of eggs’ quality parameters (egg weight, eggshell strength, eggshell thickness and egg index) was performed in two Lohman Brown flocks of commercial laying hens at advanced age. Two farms equipped with battery cages were the places where the experiment was performed. The first farm (F1) was small, family-owned farm equipped with moderately efficient ventilation, and in the second farm (F2) a highly efficient tunnel ventilation with water pads cooling equipment was installed. Egg weight and eggshell strength were analyzed in the laboratory for testing egg quality, using Egg Multi Tester EMT 5200 and Eggshell Gauge (Robotmation Co. Ltd., Tokyo, Japan), computerized equipment that gives unbiased values, while shell thickness and egg index were measured using a micrometer. No significant differences in the average values of egg size (63.09; 63.33 g), shell thickness (0.38; 0.38 mm) and egg index (75.49; 76.56) were registered between F1 and F2 farms, respectively. Average shell strength values revealed that layers kept on F2 farm produce eggs with stronger eggshell (3,434.16 g/cm 2 ) compared to the farm F1 (3,344.82 g/cm 2 ), mainly due to the fact that the drop of the eggshell quality in the first farm in the hot summer period (July) was drastic (2,914.00 g/cm 2 ). The other explanation of this situation could be the significant drop of egg size in the farm equipped with cooling pads at the beginning of the hot season (May–June) which most probably helps the layers in maintaining their Ca reserves that later help their metabolism maintain its shell-forming capacities. The conclusion is that high summer temperatures influence the eggshell strength resulting in lower strength, but the cooling equipment mitigates this negative effect.
Keywords: egg weight; eggshell strength; eggshell thickness; egg index; layersovi
|
