References

Applegate, T.J., D. Harper, M.S. Lilburn, 1998. Effect of hen production age on egg composition and embryo develpment in commercial Pekin ducks. Poult. Sci., 77: 1608-1612.
PubMed  |  

Farhat, A. and E.R. Chavez, 2000. Comparative performance, blood chemistry, carcass composition of two lines of pekin ducks reared mixed or separated by sex. Poult. Sci., 79: 460-465.
PubMed  |  Direct Link  |  

Gross, W.B. and H.S. Siegel, 1983. Evaluation of the heterophil/lymphocyte ratio as a measure of stress in chickens. Avian Dis., 27: 972-979.
CrossRef  |  PubMed  |  Direct Link  |  

Maxwell, M.H., 1993. Avian blood leucocyte responses to stress. World Poult. Sci. J., 49: 34-43.
CrossRef  |  

Mench, J.A., 1992. The welfare of poultry in modern production systems. Poult. Sci. Rev., 4: 107-128.

Michel, V. and D. Huonnic, 2003. A comparison of welfare, health and production performance of laying hens reared in cages or in aviaries. Br. Poult. Sci., 44: 775-776.
PubMed  |  

SPSS, 2001. SPSS for Windows. Version 11.0.1, SPSS, Inc., New York.

Snedecor, G.W. and W.G. Cochran, 1989. The Comparison of 2 Samples. 8th Edn., Iowa State Universty, Ames, pp: 83-106.

Tauson, R., A. Wahlstrom and P. Abrahamsson, 1999. Effects of 2 floor housing systems and cages on health, production and fear response in layers. J. Applied Poult. Res., 8: 152-159.