Sustaining laying performance in aged layers

Oxidative stress increases as animals age, which in turn can decrease laying performance. Aging also leads to variability in shell quality. Therefore, the organs and tissues involved in egg production need nutritional support, in particular protection against oxidative stress. Selenium (Se), defined as the chief executive of the antioxidant system, is involved in several levels of antioxidant defense.

The number of eggs a hen produces over her lifetime is important and as a flock, the timing of peak production, layer lifecycle and percentage should be optimal. However, eggs must be of good quality and produced efficiently. Egg quality deteriorates as hens get older. To make longer laying cycles viable, nutrition must support both eggshell strength and albumen quality. Similarly, after birds reach peak lay, performance will gradually decline. However, the speed and magnitude of this decline can be controlled using both nutritional solutions and management techniques.

1. Lengthening cycles is profitable, but can lead to decreases in quantity and quality of eggs
By extending the life of the flock, the production unit’s downtime is reduced. Moreover, financial modelling has shown correlations between persistence in lay and spikes in profitability. As breeding companies target hens that are able to produce 500 eggs per hen, it makes sense to consider longer laying cycles.

One challenge is that as birds age, their eggs become bigger. Egg mass naturally increases progressively as hens age and their reproductive system changes. Maximum egg size can be expected when birds are around one year old. Hens can suffer as egg size increases, and larger eggs tend to have thinner shells. There is a limit to the amount of calcium carbonate a hen can access from diet and bones (around 4g), therefore there is a finite quantity of shell that can be produced for each egg. If a larger egg is laid, the shell must stretch more thinly, producing a less robust egg. This will increase the number of second-quality eggs, generating waste and financial loss for the egg producer. Another challenge egg producers face with aging layers is egg quality maintenance.

Eggshell quality
The eggshell plays a crucial role in protecting the contents of the egg from the microbial and physical environment. It also controls the exchange of water and gases. Eggshell quality is made up of several factors, including soundness of the shell, egg shape and color. Improving eggshell quality means increasing shell thickness and breaking strength to reduce the number of cracked eggs and thus increase the number of saleable eggs.

Freshness
Freshness is most notably observed in the viscosity of the albumin. The older the egg, the waterier the white becomes, affecting customer perception and its functional properties (i.e., ease of making a poached egg). Haugh units are indicative of the protein content of the egg white and therefore the quality of the egg contents (freshness). Haugh units are also known to decrease with the age of the hen. Increasing antioxidant status has the potential to improve Haugh unit values.

Antioxidant status
Fat soluble compounds in the yolk are subject to oxidation. Such compounds that are used include carotenoids, which intensify yolk color, and omega 3 fatty acids, which offer increased nutritional value. By improving the antioxidant status of the hen, more of these important compounds are preserved, which improves the visual quality and nutritional value of eggs, and optimizes the use of these expensive ingredients.

Functional properties
In the food manufacturing industry, eggs are appreciated for their coloring, binding, gelling, foaming, emulsifying and nutritional properties. Optimizing these properties improves the value of eggs used in powder or liquid form. Check out our article on “Improvement of the nutritional properties of eggs”.

2. Sustaining performance and egg quality of aging hens by securing their antioxidant status
Oxidative stress increases as animals age, which in turn can decrease laying performance.

Aging also leads to variability in shell quality. Therefore, the organs and tissues involved in egg production need nutritional support, in particular protection against oxidative stress. Selenium (Se), defined as the chief executive of the antioxidant system, is involved in several levels of antioxidant defense. Selenium is included in livestock premixes, either in inorganic forms (mainly sodium selenite (SS)), which are known to have a very low bio-efficacy, or in organic forms, such as inactivated seleno-yeasts (SY) or in pure chemically synthetized forms (SeMet, hydroxy-selenomethionine: OH-SeMet), which are known to have a higher bio-efficacy. Selisseo^® is the only pure form of organic Se that consivstently provides 100% Se as OH-SeMet available on the market. Trials in laying hens have shown egg production benefits, particularly in the later stages of lay, when birds were fed Selisseo^®.

A trial conducted in Ankara (Turkey) studied the effect of Selisseo^® on laying performance and egg quality of hens aged from 63 to 90 weeks. As birds age, there is a normal increase in their feed efficiency (FCR) and a decrease in the egg production rate. However, this decrease in performance was alleviated in birds fed Selisseo^®, resulting in better overall performance. Over the entire period, the FCR was decreased with Selisseo^® by 2 and 3 points compared to Seleno-Yeast (SY) and Sodium Selenite (SS), respectively (Figure 1A/B).

Feeding Selisseo^® resulted in a 9% higher laying rate compared to SS and 4.5% compared to SY (Figure 2A/B). It also showed a reduced number of cracked and broken eggs resulting in 0.65% and 1.1% more saleable eggs per hen than SS and SY, respectively. This beneficial effect can be attributed to an improved antioxidant capacity, which in turn led to better hepatic health and function, a reduction in the MDA level in both the serum and liver, and a lower liver fat content (data upon request).

3. Improving digestive performance of laying hens for persistent quantity and quality
Efficient egg production, performance and even egg quality are linked to the gut. Adimix Precision is a precision delivery coated sodium butyrate. Thanks to its specific coating, Adimix Precision can deliver butyrate along the whole digestive tract from the stomach to the distal part of the intestine, and therefore has the potential to trigger beneficial butyrate-dependent effects throughout the entire digestive tract, thus helping hens get the most out of butyrate.

By improving intestinal health (Figure 3), Adimix Precision can sustain performance and egg quality of aged layer hens. The increase of villi height combined with a decrease of crypt depth allows for a bigger exchange surface of the intestinal wall, and thus a better absorption of nutrients. The laying percentage in standard conditions can be improved by 1.1 % and the FCR can be reduced by 2.6 % compared to control groups for layers aged between 59 and 74 weeks. Adimix Precision can even perform better in challenging conditions such as heat stress for instance.

As laying hens get older, the percentage of cracked eggs increases. But by including Adimix Precision in the diet, this tendency is reduced from 1.56 to 1.18%. This can be explained by the improvement in eggshell quality (Figure 4). There is a greater amount of shell on the egg, which reduces the likelihood of cracks and increases the number of saleable eggs. Adimix Precision can also reduce the proportion of dirty eggs. The causes of dirty eggs include, health status, diet, hygiene plan and age. In this trial, Adimix Precision reduced the proportion of dirty eggs from 3.12 to 1.32% (p < 0.05).

Conclusion
As laying hens get older, quantity and quality of eggs can decline. However, by optimizing the digestive performance (Adimix^® Precision) and antioxidant status (Selisseo^®) of hens, persistent lays can be sustained.