There are many factors that influence the fertility of eggs used for hatching. Fertility depends on the hen but also the vigourness of roosters, their feeding and genetics
Whilst it is quite obvious that the female plays a vital part in the fertility of hatching eggs, an overlooked factor can be the fertility of the male.
Small numbers to select from
In-breeding and selecting breeding birds from a small pool of stock, as often happens with dwindling numbers in rare breeds, are two factors that can influence fertility and cause it to fall. When birds become very closely related, it is usually time to seek outcrosses of other strains of the breed to maintain a vigourous and hardy breed. Early signs of poor fertility traits are birds failing to hatch or birds which are weak and do not live beyond a few days or week.
Breeding stock (in fowl, guinea fowl and turkeys) should be maintained on a diet that has at least 16% protein and probably closer to 18% for the light breeds. Minerals and vitamins are essential and deficiencies in these can occur without being obvious when the birds green pick dissappears in the dryer months. Add extra vitamins to the feed each second day to keep breeding stock healthy. Black sunflower seed and lucerne meal are excellent for adding oils and essential vitamins.
A good dose of milk whey powder sprinkled on rations each few weeks keeps the digestive tract stocked with healthy bacteria. It is also important to worm you birds regularly (every few months).
As fat hens lay fewer eggs and are more stressed, keep your feeding regime sensible. Fowl of average size need no more than 125 gm of quality feed daily, so keep your hens and roosters lean for best results.
Healthy birds will be active, have bright combs, stand erect or alert and be producing firm stools. Constantly runny stools are a sign of worm or coccicidiosis infestation and should be fixed quickly to avoid bowel tract damage.