23 Mar 2020

Improved laying hen traits demand applied nutrition

Michael Elliot PhD

Genetic progress in layer breeding has been substantial in recent decades. Results are lower body weight, increased feed efficiency,  higher productivity and longer production cycles. Consequently, this demands high quality nutrition and a feeding regime that fully fits to these changing traits. AviNews spoke with animal nutrition specialist Michael Elliot* about this topic.


How much has layer nutrition changed in the last 20 years?

“Layer nutrition has made tremendous progress in recent years. In 1992 layer feed contained little more than grain ( corn, wheat, sorghum), soybean meal, phosphate, calcium carbonate, salt, methionine, and vitamin and mineral premix.

Diets were typically formulated to a minimum of crude protein, and the amino acid specifications covered only total methionine, total methionine plus cystine, and possibly total lysine. The levels of energy, calcium, phosphorus and sodium available to meet the minimum requirement were also calculated.

Today, the most common layer rations contain corn, soybean meal, rapeseed or canola meal (where available), soluble DDG, and bakery by-product meal, wheat bran or soybean hulls, phosphate, calcium carbonate, sodium, methionine, lysine, threonine, phytase, non-starch polysaccharide (NSP) enzymes, and a vitamin and mineral premix.

Today’s diets are formulated to a minimum of energy, calcium, available phosphorus, sodium, chloride, and choline. Feed formulation is no longer done with a minimum of crude protein. Instead, diets are formulated to include a well-balanced amino acid profile containing the required minimum of lysine, arginine, methionine, methionine plus cystine, tryptophan, threonine, isoleucine, and valine.

An additional important change is that in the past one type of feed was used, whereas nowadays we use multiple phase diets which are  based on the age of the hens. These are formulated for a specific level of feed consumption.”

What caused the revolution in layer feed formulation?

“This has been caused, at least to some part, by research into enzymes and nutrient availability, digestibility and required amino acid ratios, ingredient cost, and improved genetic potential.

The age at which the first egg is laid has been reduced by one week every 5 to 7 years, the size of the first eggs has improved, and the laying period has been optimized. A good flock today will produce 260 eggs per hen housed or even more at 60 weeks of age, a tremendous  improvement compared to the 230 eggs produced in the same period in 1992.

In addition, body weight has decreased significantly and this has positively influenced feed consumption.”


* Michael Elliot, PhD is an independent animal nutrition specialist. He founded and runs A&E Nutrition Services in Lancaster, PA, USA. Michael Elliot is specialised in feed formulation and nutrition of commercial egg layers.


“Layer nutrition has made tremendous progress in recent years”


Which is the most important progress  in feed formulation related to amino acid and protein?

“In commercial layer diets the levels of amino acids and crude protein have decreased because nutritionists formulate layer diets based on amino acids instead of crude protein.

Feeding for early egg size (early laying) is critical to profitability. The use of low amino acid in pre-laying or pre-peak diets is one reason for the inability of many flocks to achieve production targets for maturity, initial egg size (early laying or early laying) and peak production.

A maximum amount of protein in the diet, along with high levels of amino acids will influence early egg size. In addition, increasing dietary methionine levels relative to lysine levels will also increase early egg size. This is now a commonly used tool for improving early egg size in layers. It should be noted that the order of limiting amino acids in a corn-soy diet (as the crude protein level decreases) is methionine, threonine, lysine, valine, arginine, and tryptophan.

Therefore, commercially available threonine has made it possible to significantly decrease the crude protein level for layer diets. This is perhaps the most important progress in relation to crude protein and amino acids and their use in layer nutrition.

When synthetic methionine and lysine are used in formulations, crude protein can be reduced by up to 1% without adversely affecting egg production. An additional 1% reduction can be achieved with minimal impact on performance.

It is therefore possible to reduce the level of crude protein and the cost of production when formulating diets with synthetic methionine, lysine and threonine and the proper inclusion of dietary isoleucine levels.

A high level of isoleucine should be used at the beginning of the egg production cycle (early laying or laying) to achieve a good egg weight at the beginning of the production cycle, and this isoleucine level can be gradually reduced as the age of the flock increases. Carefully implemented, the phased formulation of amino acids will decrease feed cost, maintain optimal body weight, and control egg weight later in the production cycle without affecting the entire production cycle.

“When both methionine and synthetic lysine are used, we can reduce the crude protein in the feed by 1% without affecting egg production”

Total Sulfur Amino Acid (TSAA) profiles can be used to influence egg size. For example, higher TSAA profiles may be necessary in farms using breeds that tend to produce smaller eggs at the start of egg production.

Generally speaking, a lower proportion of TSAA, isoleucine and threonine is used for small eggs compared to the rate which is used for producing large eggs.

Good early egg size and mass is desirable, but egg size must be controlled to avoid the production of large eggs with poor shell quality later in the production cycle. This can be controlled without affecting production by reducing TSAA, threonine, and isoleucine to lysine ratios in conjunction with linoleic acid levels, which are reduced with the age of the layers.

There are considerable differences in the amino acid requirements for white or brown layers and feed should be formulated with these differences in mind. For example, lysine levels may need to be generally higher for brown layers.”

Which progress is made in relation to calcium and phosphorus?

“Pullet diets should contain approximately 1.10% calcium and 0.45 to 0.50% phosphorus available for optimal skeletal development. Early maturing birds require a diet containing 2.50 to 2.75% calcium and 0.45 to 0.50% available phosphorus.

This type of diet should be used 7 days prior to light stimulation and not be used for more than 7-14 days after the first feeding. Hens in the early production stage should be started with 3.90 to 4.10 g / hen / day of calcium and 430 to 470 mg / hen / day of available phosphorus. Lower levels may result in poor shell quality in the productive life of the flock.

“Feed for brown and white hens is different since their amino acid requirement is different”

The daily intake of calcium should be gradually increased and the daily intake of phosphorus decreased as the age increases because the efficiency requirements of calcium and phosphorus utilization decrease with age. Fifty percent of all supplemental calcium in the diet should be supplied in the form of coarse particles (2-3 mm).

The coarse particles of calcium carbonate should be gradually increased to approximately 70 percent of supplemental limestone during the production cycle. Fine calcium carbonate particles pass through the gastrointestinal tract in 2-3 hours.

When no large particles of calcium are present in the digestive tract while the eggshell is being produced, calcium will be obtained from the bones, which eventually results in loss of skeletal integrity, poor shell quality, and leg disorders.

Regarding the availability of phosphorus to young and adult birds, there is considerable disagreement among nutritionists, partly due to a poor understanding of the availability of plant-based phosphorus, the actual impact of exogenous phytase on phosphorus availability, and the ratio of phosphorus to shell quality and feed cost.

Added to this is the fact that phosphorus is expensive and some reports have suggested that reducing phosphorus in the diet may occasionally improve shell quality. However, this practice may result in increased mortality, bone problems, and production loss at the end of the cycle. The use of the enzyme phytase in North America has become extremely common.

In the United States, the industry standard has been the use of 300 FTU/kg of fungal phytase with 0.09% available phosphorus and 0.09% calcium. At 300 FTU/kg, fungal phytase will decrease phosphorus excretion by 15-18%. Due to significant cost savings I have moved all my nutrition programs to 500 FTU/kg phytase.

Are there any new concepts about the use of fat, linoleic acid and enzymes?

No. The added fat is beneficial for egg size at the start of production and for the yield. The effect of the added fat on the weight gain of the egg is independent of the level of dietary energy.

Linoleic acid from vegetable oils is necessary for optimal egg size. The use of non-starch polysaccharides (NSPs) in layer diets worldwide is now common practice, as they improve digestibility, enhance performance, and decrease variability as well as nutrient excretion and thus feed cost.

To maximize early egg size in smaller breeds, diets should contain a maximum of 2.00% linoleic acid towards peak production. In larger breeds a minimum of around 1.50% linoleic acid is sufficient.

Good sources of linoleic acid are corn, vegetable oil, extruded soybean and rice bran.


“Phytase inclusion in layer diets significantly cuts costs”


Which are the new concepts of interaction between management and nutrition?

Egg shell quality is fundamental to profitability and must be optimized and kept. Shell quality is influenced by genetics, nutrition, feed management, body weight, age at light stimulation, heat stress, egg collection, egg collection belts, housing systems, grading and packing, diseases and gut health, to name a few factors.

Breeding companies recommend specific body weights for each genetic strain prior to light stimulation. Light stimulation in hens with a too low weight, will cause them to enter production before they are physiologically ready. These birds tend to maintain a low weight throughout their productive life and are susceptible to bone disorders. Moreover shell quality will be poor.

On the other hand, stimulation of hens with too high body weight will result in overweight and oversized eggs, also resulting in poor eggshell quality.”


“Probiotics can indirectly improve eggshell quality”


How should layer nutritionists approach shell quality problems?

“This is a complex issue that requires lengthy discussion, but in general the first thing they should do is to ensure that the feed formulated and produced is the right one at all stages, and also that it is being manufactured correctly.

Treatment should be implemented if decreased shell quality is associated with increased mortality:

– Week 1: Increase the level of dietary calcium by an additional 0.60% and the level of available phosphorus by 0.14

– Week 2: Increase calcium level by 0.30% and available phosphorus level by 0.07%

– Week 3: return to normal diet or with 0.15% more calcium and 0.035% more phosphorus available continuously

However, if reduced shell quality is not associated with increased mortality, dietary calcium should be increased by an additional 0.30% and additional dietary vitamin D3 should be provided.

Vitamin D3 supplementation (2,500 IU/litre of drinking water) may also be used by administering it in the water for 7 consecutive days and 2 days apart for each week thereafter. Numerous studies have suggested that the amino acid – zinc complex and manganese may improve performance and eggshell quality. Also probiotics can indirectly improve eggshell quality.”

What can you tell us about the use of dried distiller’s grains with solubles (DDGS) in layer diets?

DDGS have indeed become a commonly used ingredient. Over 50% of the layer formulations in the US now contain DDGS with inclusion rates ranging from 5 to 20%.

This wide range is due to quality and variability, formulation technique (relative to amino acids) and differences in views regarding recommended levels of use.

“We are living in exciting times in laying hen nutrition “

In general, layer performance tends to drop when DDGS levels exceed 12%, while the optimal level of inclusion to keep production costs low and efficient should be around 15% DDGS.

It is important to mention that the energy value of DDGS can be overestimated and therefore care should be taken in the calculation of total energy levels when DDGS levels in the diet are high.

“More than 50% of layer formulations in the USA contain DDGS with an inclusion rate between 5 and 20%”

In addition, there are some anti-nutritional factors in DDGS, but formulation on a digestible amino acid basis can compensate for these anti-nutritional factors by also using available synthetic methionine, lysine, threonine and tryptophan, and by utilizing services such as Evonik’s Amino Network service in the NIR to assess amino acid digestibility and constantly recalculate energy content to adjust for protein, fat and fibre.”








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