Scienceline Publications Journal of World's Poultry Research 2322-455X 6 1 2016 March Effect of Sex Ratio on the Production and Hatchability of Broiler Breeder Flock 14 17 http://jwpr.science-line.com/attachments/article/35/J%20World%20Poult%20Res%206(1)%2014-17,%20March%2025,%202016.pdf EN Mehdi Haghighi MSci Student of Animal science, Ghaemshahr Branch, Islamic Azad University, Ghaemshahr, Iran Mehrdad Irani Animal Science Department, Ghaemshahr Branch, Islamic Azad University, Ghaemshahr, Iran Mehdi Jafari MSci Student of Animal science, Ghaemshahr Branch, Islamic Azad University, Ghaemshahr, Iran Sobhan Firouzi DVM – Ph.D. of Poultry Sciences, Babol, Iran Hassan Habibi Department of Animal Science, College of Agriculture, Persian Gulf University, Bushehr, Iran Trials to compare mating ratios are important for optimizing the breeding efficiency of broiler breeder flocks. The study provides information on the reproductive performance of broiler breeder flock (Ross308) maintained at different male: female (M: F) ratios. 381, thirty week-old broiler breeders were randomly divided into three experimental groups with three replicates each and were assigned to one of the following male: female ratio, 1M: 13.3F, 1M: 11.6F and 1M: 10.5F. The birds were randomly allotted to 9, 2m x 2m floor pens in an environmentally controlled house. Eggs were collected daily and weekly egg production/bird was calculated for each group. Hatchability and egg production were significantly affected by sex ratio. 1M: 13.3Fgrouphad significantly higher egg production. Hatchability of 1M: 10.5F were significantly the highest followed by 1M: 11.6Fand that of 1M: 13.3F sex ratio were the lowest from week 33.Increasing the sex ratio had the effect that although average egg production/female was lower, but hatchability were improved, possibly as a result of more frequent sexual interactions of males and females. Sex ratio, , , Broiler breeder Hatchability Production