The quality comparison of eggs laid by laying hens kept in battery cages and in a deep litter system

At present the laying hen rearing is transformed into alternative housing systems which include a deep litter system. As for the poultry nutrition, the replacement of animal protein with vegetable protein in poultry feed is applied. Therefore, in an experiment we evaluated the quality of eggs from laying hens in the cage system as compared to the deep litter system with vegetable protein substituted for animal protein in their feed. 72 ISA Brown laying hens were placed into the experiment. 36 laying hens were kept in the deep litter system and 36 laying hens were kept in conventional cages for laying hens. For the period of 9 months, 36 eggs from the group in the deep litter system were examined, always at intervals of five weeks (i.e. 8 × 36 eggs) and so were 36 eggs from the group in the cage system (i.e. 8 × 36 eggs). We found out that in the deep litter system the mean egg weight was higher (P < 0.01), shell weight was lower (P < 0.01), egg albumen was higher (P < 0.01), yolk weight did not differ (P > 0.05), yolk cholesterol was higher (P < 0.01), yolk colour was darker (P < 0.05), shell strength did not differ (P > 0.05), all in comparison with the cage system of laying hen keeping. The results of the experiment show that where vegetable protein was substituted for animal protein in the nutrition of laying hens, there were differences in the quality of eggs from laying hens kept in the deep litter system and eggs from laying hens kept in the cage system.