A phytogenic feed additive improves egg shell quality and tibia breaking strength in 90 weeks old laying hens



Extending the production period of hens without moulting has both financial and environmental benefits. However, egg shell quality deteriorates with hen age. Thus, extending the laying cycle is only interesting when simultaneously maintaining laying persistency and stabilizing egg shell quality. Deterioration of egg shell quality is related to the increase of egg size with bird’s age, whereas egg shell weight does not increase resulting in a thinner egg shell. In addition, changes in the egg shell microstructure and its organic matrix occur due a.o. to less effective vitamin D metabolism. Some phytogenic feed additives have been shown to improve calcium digestibility in aged laying hens, as well as calcium deposition in egg shells and bone.



The objectives of this study are:

© Werner Dedl / Delacon


Material and Methods

  • 200 ninety week old ISA Brown laying hens were assigned to two experimental groups with 20 repetitions, each repetition with 5 laying hens.
  • Hens were kept in enriched cages.
  • Birds of control group were fed a diet based on wheat, corn and soybean meal, meeting the ISA Brown nutritional requirements (management guide). Birds of the treatment group (PFA) were fed the control diet supplemented with 250 mg/kg of the tested phytogenic feed additive.
  • Egg shell breaking strength was measured weekly from 100 eggs per treatment.
  • Tibia breaking strength was measured after the 10 week trial period at an age of the laying hens of 90 weeks.
Figure 1

Figure 1: Addition of a phytogenic feed dditive significantly (P=0.029) improved egg Shell breaking strength over time in laying hens


Results & Discussion

  • The addition of the phytogenic feed additive did not influence performance (feed intake, FCR, laying rate, body weight) of the laying hens.
  • The addition of the PFA significantly (P=0.029) improved egg shell breaking strength from 4.3 to 4.6 (breaking force in kg) for the whole 10 week trial period (Figure 1).
  • Laying hens fed on the phytogenic feed additive had a significantly (P=0.035) higher bone breaking strength compared to the hens of the control group (Figure 2).
Figure 2

Figure 2. Addition of a phytogenic feed additive significantly (P=0.035) improved bone breaking strength after 10-week experimental period (hen age at end of experiment was 90 weeks)




Results of this study show that the tested phytogenic feed additive improves egg shell quality and tibia breaking strength in old laying hens, which improved profitability of egg production.



This poster was published by L. Jungbauer, A. Mueller and J.D. van der Klis and was presented at European Symposium on Poultry Nutrition 2017.

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