How to hatch more hens

I thought I would do a post on how to hatch out  a more equal percentage of chicks from the book 'Sexing All Fowl'. The proportion of male chicks hatched is important to the hatchery man, particularly if he is hatching hens for a laying flock replacement, because the cockerels don't have much value.  (Poultry Science, Vol. 33,No.2).  The older the sire , the higher percentage of male chicks hatched, according to F.A. Hays,University of Massachusetts, who analysed the sex ratio in 614 family's of  Rhode Island Reds bred for high production . The study extended over 5 years , and it involved 93 sires. Where the 1 year old males were used, the percentage of male chicks was 50.49 percent,2 years, 54.21 percent; 3 years 53.07 percent; and 4 years ,62.90 percent. Hatching rate or fertility did not seem to affect sex ratio, but the hatch ability did. Where there was low hatch ability, there was a  larger number of cockerel chicks. This agrees with work of other investigator's that female embryos are more likely to die then male embryos.  Sex ratios were unaffected by annual egg production, egg production during mating season , egg weight , and the age of the females in the breeding. Info by Roland C. Hartmen in the book 'Sexing All Fowl'.