Generally, eggs are formed in the reproductive organ of the female chicken every day in what looks like a production line consisting of the ovary and the oviduct.
Local Kienyeji chickens under good foraging and supplemental feeding can give you 200-260 eggs annually. Commercial hybrid hen can produce 330 eggs yearly, that is almost one egg per day with good genetics, diet and conducive environment. It takes about 25 hours to produce and lay an egg in the female fowl.
However, during the period of egg production, things can go wrong, and eggs come out in different shapes, colour, size, shell abnormality and weight. Here are possible causes and remedy.
1. Blood stained egg surface
Unlike other animals that have separate reproductive and gastro-intestinal openings, chickens share the same opening for both eggs and feaces. It is called the cloaca. If you notice blood stained egg shell condition in your egg store, it is likely due to damage of the cloaca. This can happen due to pecking by other birds, birds laying too early first eggs while still immature or overstimulation of the ovary. To avoid this, avoid early light stimulation, reduce light intensity and beak treat to reduce pecking behaviour.
2. Mishappen eggs
It is common in young birds at start of lay and older birds towards end of production, it can be as a result of Infectious bronchitis disease, egg drop syndrome or Newcastle disease. Ensure your flocks are fully vaccinated before they come into production.
3. Extremely small eggs
This can happen if you expose the immature birds to early lighting or when birds come to lay before 18 weeks of age. High environmental heat stress can also cause low feed intake leading to small egg size. In such situation ensure the feed is of higher energy density and feeding is done during the cool times of the day or at night.
4. Corrugated and rough shell eggs
Rough shell eggs appearing with excessive deposits on the broader top could be due to excessive calcium in feed, diseases like Mycoplasma or extreme stress especially at night. It is common in older flocks towards end of production.
5. Thin, porous and soft shell, shell less
The eggs are laid with poor soft egg shell thickness, they easily crack and will affect all flocks on the same feed. It is associated with imbalance in zinc, manganese, phosphorus, calcium or vitamin D. It can also occur in situations of under feeding, high temperatures and sudden disturbances at night during egg formation. It can also occur if birds are on high salty water or fed on mycotoxins contaminated raw materials. Did you change feed supplier recently? Check.
6. Discoloured egg shell
Most Kenyan farmers are familiar with brown coloured table eggs. The reason is most genetics sold here are ISA Brown, Hy-line and Lohman brown. The degree of brown colour in the egg shell depends on quality of pigment deposited on the shell. In diseases like Infectious bronchitis the colour of shell turns to pale and eventually white. Excessive use of antibiotics like Tetracycline may change the colour to yellow, other anticoccidial drugs may also alter the brown colour of egg shell. Keep your vaccination up to schedule.
7. Cracked egg shell
If you are seeing a lot of cracked eggs at the egg storage area, make sure that the nest boxes are enough, excessive birds per nest may cause unnecessary cracks. Four to five birds per nest is most ideal. Egg collection should not be delayed at all, five to six egg collections per day is highly recommended. Avoid rough handling of eggs, pack eggs carefully and never stack more than eight trays high. As flocks age, eggs shells generally become weak due to low calcium in the diet. Therefore supplement calcium grits just before lights are out.
8. Mottled shell eggs
If eggs are placed in front of light source, the translucent areas of the shell appear mottled or glassy as a result of delayed quick dry out. Causes are unknown but it is associated with high house humidity, high levels of mycotoxins in feed, magnesium deficiencies and overcrowding in the pen.
[The writer is Head Vet, Kenchic Limited. Email [email protected]]