Low rate of embryos in eggs is often caused by:
- The male-female rate of the parent flock is not suitable: insufficient or
- excessive number of roosters.
- Imbalance of maturity or size between males and females also affects mating success.
- Spurs are not trimmed causes severe scratching of hens and then hens will run from mating attempts or roosters have malformed toes making it difficult for them to keep balance on the back of the hens during mating.
- Improper design of the breeding house, affecting the roosters and hens.
- The parent flock is diseased.
- Improper feeding practices of the parent flock leading to overweight or late sexual maturity (especially for roosters).
- Inadequate space – crowding also creates problems. Too much space can also reduce successful matings.
- Mite or ectoparasite infestations dramatically affect male fertility