There was once a prediction of reaching 500 saleable eggs in 100 weeks per hen which became a reality for the Dutch poultry farmer, Simon van Loon. This was due to good management, not starting the production too early and using a docile hen to prevent pecking. Selective eating was also prevented by ensuring the feed system was empty for at least one hour per day. Nowadays still, the best way to increase the number of eggs produced is by increasing the length of the laying cycle. Longer cycles can help to reduce costs and increase egg production, without the need for a molting period.
However, longer cycles can produce negative side-effects, such as decreased laying rate and calcium absorption, bone fractures, more variable brown shell color, larger eggs with decreased shell percentage and a decline in shell quality. Calcium absorption decreases with age and the reduced intestinal uptake and increased egg size can lead to a decline in eggshell quality. Vitamin D status can also decrease with age, which can lead to a decrease in eggshell strength, resulting in an increase of cracked and soft shells. Other side-effects from long cycles include feather pecking and cannibalism, increased mortality and overweight flocks with high abdominal fat deposition.
There are three main areas of focus to help ensure better shell quality - bone, liver and gut.
The bone structure of a hen changes over time; from the first egg onwards, both the trabecular and cortical bone are reabsorbed, increasing the risk of occurrence of osteoporosis and fractures. Cortical bone formation is critical in the rearing period, especially in the first 6 weeks, but the bones continue to calcify throughout the rearing period. The medullary bone contributes 35-40% of the calcium for eggshell formation. It is important to achieve the correct feed intake at the onset of product as failure to do so can adversely impact shell quality and skeletal integrity for the lifetime of a flock. It is also important to encourage drinking and stimulate the increase of the feed intake.
Fatty liver syndrome is frequently seen in layers and breeders. This occurs when an excessive amount of fat accumulates in the liver cells, causing them to lose their functionality. The liver becomes soft and damaged and is prone to bleeding. This means the hen is unable to export lipoprotein to the yolk and it decreases the liver’s ability to hydroxylate dietary vitamin D3 to 25-OH-D3, the active vitamin D form. This can then lead to a decrease in feed intake and egg production, as well as an increase in bone mobilization leading to skeletal damage. It is important to keep the liver healthy during a longer cycle. This can be done by using nutrients and vitamins, such as choline, betaine, vitamin E and B12, selenium and Hy-D® (25-OH-D3), and also by supplying a minimum amount of high quality lipids as an energy source. Avoiding fatty birds by controlling energy intake also helps to prevent fatty liver, as well as fragile shells and skeletal damages.
A healthy gut results in a balanced microflora, which can be achieved in a number of ways. Dietary fiber can help to develop the gizzard and promote the digestive tract development. The gizzard can also be developed with the use of coarse calcium and insoluble grit. Eubiotics help to balance the gut
flora and feed enzymes play a role in decreasing viscosity and promoting better digestibility and clean eggs. Using fiber in the feed can also decrease mortality; for example, extra insoluble fibers can reduce feather pecking and associated mortality, both at rear and lay. They can also increase the feeling of satiety, which can delay feather damage, and increase the time spent eating. Gut flora normally produces short chain fatty acids, such as butyrate. This enables better villi growth, epithelial growth and metabolism. It can also support the liver function and improve shell quality in old hens.
It is well recognized that taking good care of the bird’s skeleton and gut and liver function through appropriate attention to micro-nutrition will help ensure a long, productive lay cycle. This will lead to more sustainable egg production and greater value creation for the farmer.
Pullet development is crucial to achieving a successful layer. Building structural bone and medullary bone in the pre-lay period is a key element of a longer lay cycle along with maintaining healthy gut and liver function throughout the life of the bird. This is achieved through providing appropriate levels of micro-nutrition during the bird’s development and productive lay period. Focus on the correct levels of phosphorus, calcium and vitamin D3 (especially 25-hydroxy-D3 which is the active, more bioavailable form of vitamin D3).