Duran  Ozkok, Kaan  M. Iscan, Sibel  Silici, 
    Effects of Dietary Propolis Supplementation on Performance and Egg Quality in Laying Hens,
    Journal of Animal and Veterinary Advances,
    Volume 12,Issue 2,
    2013,
    Pages 269-275,
    ISSN 1680-5593,
    javaa.2013.269.275,
    (https://makhillpublications.co/view-article.php?doi=javaa.2013.269.275)
    Abstract: This experiment was conducted to evaluate the efficacy of 
  supplemental propolis on the performance and egg quality of laying hens. Two 
  hundred and forty, 18 weeks old Bovans White strain laying hens were divided 
  into four groups of 60 each. They were fed 0 (P-0), 100 (P-1), 200 (P-2) and 
  400 (P-4) mg kg<SUP>-1</SUP> of supplemental propolis for 32 weeks. Feed and 
  water were supplied <I>ad libitum</I>. The live weight of the animals was weighed 
  before and at the end of the experiment whilst feed consumption, feed conversation 
  ratio, egg production, egg weight, mortality, Haugh unit and shell thickness 
  were determined at 28 days intervals throughout the experiment. At the end of 
  the study, it was determined that the live weight of laying hens fed on a diet 
  supplemented with 400 mg kg<SUP>-1</SUP> propolis had increased (p&lt;0.05). 
  However, propolis doses used in this study did not have significant dietary 
  effects on either performance criteria including feed consumption, feed conversation 
  ratio, egg production, egg weight, mortality or egg quality criteria including 
  Haugh unit and shell thickness (p&gt;0.05). In conclusion, as the results of 
  the present study demonstrated that in laying hens, supplementation of the ration 
  with propolis did not induce any adverse effect on performance, egg quality 
  or survival rate, it is suggested that various doses of propolis could be used 
  in egg production.
    Keywords: performance;propolis;Laying hen;egg quality;group