Shell Quality - a complex issue needs a complete solution

29 October 2020

Shell quality is one of the most important factors in egg production but there are so many aspects that can influence it that a solution to reduced shell quality is not always easy to find.


As flock age increases, so does the risk of eggshell quality problems and older hens have a less efficient uptake of calcium from their feed compared to younger birds. This poor utilisation of calcium from the diet in combination with an increase in egg weight can reduce eggshell quality. Eggshell quality problems are often multifactorial and managing an eggshell quality problem starts with a proper analysis of the specific situation on your farm. This should include assessment of management and environmental factors as well as nutrition and feeding. Management and environmental causes can include (but is not limited to) things such as mechanical damage (rough handling, damaged collection systems), flock age (younger birds with immature shell glands may produce soft eggs while older birds tend to lay larger eggs which are more prone to thinner or weaker shells) and elevated temperatures that could lead to heat stress, metabolic alkalosis and a reduction in the amount of calcium available for shell mineralisation. Heat stress reduces feed intake and thus intake of calcium and vitamin D3. It also results in reduced levels of calcium carbonate, the most important component of the eggshell. Mild heat stress can already have an impact on eggshell quality before signs of discomfort such as panting and spreading wings become visible. A lot of viruses causing respiratory disease in poultry can also have a negative impact on egg production and eggshell quality. Some of these viruses cause permanent damage to the shell gland, whereas some other viruses cause a temporary drop in egg production and/or egg quality. Contamination of feed with mycotoxins also has negative effects, with Ochratoxicosis in particular being associated with thin eggshells. It is important to work with your vet to ensure you have a robust health programme in place, and with your feed or premix supplier to ensure feed safety standards are as high as possible.


With regards to nutrition and feeding, the diet should contain sufficient calcium and vitamin D3, as well as a correct ratio between calcium and phosphorus. Other important micronutrients are selenium, copper, zinc and manganese. Chloride can have a negative impact on eggshell quality so sodium chloride levels in feed and/or drinking water should not be too high. Improving eggshell quality through the diet using concepts such as split-feeding can have a dramatic impact. The formation of the eggshell is a process that takes 18-21 hours and mostly takes place late in the afternoon and during the night. As a result, the requirement for calcium supply through the diet goes up during this period. A split feeding concept, with increased levels of protein in the morning feed, in combination with increased levels of calcium, vitamin D3 and trace elements required for eggshell formation in the afternoon feed will produce better quality eggs. Selenium has also been linked to improved shell quality and improved tibia mineralisation – an important reservoir of minerals for a laying hen. Including organic selenium sources (such as Selko Optimin SeY) rather than sodium selenite in layer rations has been shown to increase tibia resistance, tibia weight and eggshell breaking strength (Figure 1 and 2).


Farm-O-San Shellboost contains calcium butyrate in combination with vitamin D3 in the form of Hy-D/25-hydroxy D3. The combination of these two ingredients results in an improved uptake of calcium, leading to a better eggshell quality. Calcium butyrate also stimulates growth of gut cells and improves the tight junctions between those cells. This benefits gut health, which results in a better uptake of other nutrients. The inclusion of essential trace elements such as zinc and manganese improves formation of the egg membrane which supports the eggshell, and Shellboost has been shown to improve the breaking strength of eggs (see Figure 3).


Farm-O-San AHS is a complete solution that contains bicarbonate to aid in normalising the body pH and help the bird to mobilise sufficient calcium carbonate for eggshell production. Other components of AHS will help keep feed intake at the desired level. This in turn helps maintain intakes of nutrients that support egg production.


Reviewing all factors that can influence eggshell quality on your farm is essential to develop a control programme that effectively addresses the issue, and a robust eggshell quality program will help you improve and maintain premium eggshell quality. Trouw Nutrition can help you to find an approach that will work for you.