Effects of dietary lysine level and white laying hen's strain on performance, egg quality and intestinal morphology

Egg production and feed efficiency of laying hens have increased in the last few decades. Therefore, it is important to correctly determine the amino acid requirements of laying hens to reach their full genetic potential. In this thesis, it was aimed to investigate the effects of different lysine levels on performance and egg quality parameters and intestinal morphology of 3 different commercial laying hen lines. In this study; 240 Bovans, 240 Lohmann LSL-Lite and 240 Hy-Line W80 commercial laying hens between 27-67 weeks of age were randomly feeds containing different digestible lysine levels (685;650, 767;730 and 850; 810 mg/hen/day) for 2 periods were distributed in groups of 16 replicates. Egg mass and egg weight increased with increasing lysine level (P < 0.05). There was no significant effect of different lysine levels on egg production (P > 0.05). While increased lysine level did not affect feed consumption statistically (P > 0.05); improved feed conversion ratio (P < 0.05). Different lysine levels; mortality rate, cracked egg rate, double yolk egg rate and blood spots did not affect (P > 0.05). At the same time, feed efficiency, cracked egg rate and mortality rate did not change depending on the strain (P > 0.05). Eggshell strength, shell thickness and shell ratio increased with decreasing lysine level (P < 0.05). With increasing lysine level, the height of the villi increased while their width decreased (P < 0.05). Overall, in this thesis, it was observed that different lysine levels had significant effects on laying hens. Depends on requirement of the egg industry, it has been concluded that a production with low egg weight can be achieved by considering lower lysine levels in laying hen diets