The effects of diets incorporating natural source of tannins on laying hens’ production performances and physical parameters of eggs

Abstract This study aimed to evaluate the effects of natural tannins in laying hens’ diets on production parameters and the alterations of eggs’ physical properties during storage time and temperature. A six weeks experiment was carried out on 168 Lohmann Brown laying hens, 51 weeks of age, accommodated within digestibility cages, structured on 3 levels. The dietary basic structure was the same for all 3 tested groups. The difference between the experimental and control groups was established by the type of plant additive added E1 (0.5% chestnut flour) vs. E2 (0.5% bark oak). At the end of the experiment, 36 eggs/group were collected to evaluate internal and external quality parameters of eggs during storage. These eggs were divided into two parts: 18 eggs/group were kept at room temperature (22°C) and 18 eggs/group were kept in the refrigerator (4°C) for 42 days and analysed to determine shelf time. The results obtained showed that the physical parameters of eggs laid by hens fed with diets supplemented with natural source of tannins (chestnut powder and oak bark) were improved in terms of Haugh Units, yolk colour and eggshell thickness, but only in refrigeration storage conditions.