Feeding for Genetic Potential: Technical highlights from the Hendrix Genetics Nutrition Guide for laying hens

It introduces standardized ileal digestible amino acids alongside total and apparent faecal digestible values, refines calcium and phosphorus strategies for bone and shell health, and adds deeper guidance on feed management, water quality, processing, storage, alternative raw materials, and mycotoxins. The goal of this publication is to summarize the most relevant updates and translates them into practical actions for pullet growers, egg producers, and feed mills, with the clear goal to motivate readers to download and discover the full Nutrition Guide.

Standardized ileal digestibility estimates amino acid availability before hindgut fermentation and corrects for endogenous losses more rigorously than apparent faecal digestibility. Because there is no amino acid absorption post‑ileum, SID values better represent true availability. The practical rule is simple, always align your raw material matrix with the method used in formulation. If your matrix is AFD, use the AFD tables from the guide. If your matrix is SID, use the SID tables. Do not mix systems inside a diet. Cross‑checking against CVB data in the guide helps keep ingredient assumptions realistic. Reducing crude protein while holding the digestible amino acid balance stable lowers nitrogen excretion and typically improves feed conversion. When crude protein is reduced, add valine and isoleucine constraints to protect egg mass and feather cover. Keep an eye on limiting amino acids across common ingredient sets, methionine plus cystine in soy products, valine and isoleucine in wheat or meat and bone meal, and adjust synthetics accordingly.

Performance at 80, 90 or 100 weeks depends on what happens before 18 weeks. The body weight at five weeks and at transfer predict later egg size and the flock’s ability to hold a high peak. Uniformity should be over eighty five percent in brown laying hens and over ninety percent in white egg laying hens. Starter and pre‑starter feeds need broiler‑like amino acid ratios and crumb or micro‑pellet presentation to protect intake and comfort after beak treatment. In grower diets, reduce energy slightly to stimulate feed intake and train pullets to eat mash if that will be used in lay, with fines under ten percent and particles over 3.2 millimeters avoided to prevent selective eating.

From ten weeks to pre‑lay, the developer diet should be lowered in energy through the inclusion of coarse insoluble fiber, as this will develop the crop and gizzard and supports in training of the pullets to develop their appetite. Laying hens must be able to lift feed intake by around forty percent in the first weeks after the first eggs have been produced. Pre‑lay diets should be introduced roughly ten days before the first eggs are being laid, as the inclusion of 2.2 - 2.5% calcium is used to build the medullary bone reserves. Golden rule: change feed phases based on body weight and uniformity, not just on calendar age.

Feeding during lay must be simple to execute and gradual in change. The guide defines Layer 1 through Layer 4 and adds a late phase for flocks up to 120 weeks. Early lay requires higher fat and precise digestible amino acid supply because intake is still growing and the laying hen is not yet at adult body weight. Later feed phases dilute energy gently, whilst keeping amino acid ratios steady, and include insoluble fiber to support feather condition and the feeling of “satiety” in cage-free housing systems. Only move to the next feeding phase when daily egg mass begins to decline, not on age! New insights allow slightly lower lysine levels while protecting egg mass and shell quality when the overall amino acid balance is respected.

Energy demand rises in barns, aviaries, free range, and organic, driven by activity and thermoregulation. In alternative housing systems, raise dietary energy by 7 – 12 % compared with cages, while keeping amino acid density steady. Monitor body weight weekly until peak, then monthly, and monitor feed intake and changes in bodyweight closely after transitions in the dietary phases.

The 2025 guide refines calcium and phosphorus ratios in rearing to align with ideal bone development and introduces a deliberate under‑oversupply strategy in early lay. Training laying hens to utilize calcium efficiently by feeding closer to their actual needs, rather than overfeeding, provides long‑term benefits in eggshell quality and bone health. Lower calcium in early lay also opens formulation space for both energy and amino acids and encourages feed intake when diets are least palatable because calcium sources reduce diet attractiveness.

Egg size increases with age while calcium absorption efficiency falls, so calcium levels are increased gradually over time. Recommendations sit slightly above the hens’ calculated need to protect laying performance. Housing systems matter, as laying hens in alternative housing systems typically have better bone health and can seek additional minerals, for example pecking stones, while cage birds cannot. Minimum and maximum levels in the guide reflect both systems.

Use coarse limestone between 2 - 4 mm for slow overnight release, and fine limestone (<0.5 mm) for rapid replenishment in the morning, especially in white egg layers who often finish shell formation after the lights are switched on. Avoid intermediate particle sizes where absorption is poor. Top dress coarse calcium in the late afternoon, two to four grams per bird, when feed intake is low, to improve availability of calcium during the night. Maintain a sensible retainable phosphorus level and leverage phytase to lower total phosphorus load without compromising egg shell quality or bone health.

Egg mass responds linearly to digestible amino acid intake within a working range. Methionine, cystine and lysine strongly influence egg size, threonine and tryptophan have smaller effects but remain essential. Practical egg size control blends nutrition with management (which is already starting at the rearing farm). Use vegetable oils rich in linoleic acid to lift egg weight in early lay when markets require larger eggs. Reduce oil gradually towards the end of lay to prevent oversized eggs when the market penalizes them. Always correct for feed composition changes when calcium rises at pre‑peak, otherwise you dilute the dietary energy unexpectedly.

Texture drives feed intake and gut development. Present starter feeds as high‑quality crumble or micro‑pellets and transition to mash or coarse pellets from roughly five weeks onward. Target at least 70% of particles between 1 - 3.2 mm in developer, pre‑lay, and layer diets, with fines below 10%. Hammermills grind by impact, roller mills by compression and shear, and multicrackers by cracking. Obtaining a coarse texture is easier with roller mills or multicrackers. Grind only the ingredients that needs grinding, check the texture twice per weekly, and maintain screens and speeds. After pelleting, ensure at least twenty five percent above one millimeter from five weeks onward to keep the gizzard active.

Dosing accuracy, premixing of micro‑ingredients, and mixing homogeneity are non‑negotiables. Use premixes at or above three kilograms per tonne to improve distribution, and verify mixing with microtracers. Control static buildup and heat in mixers to avoid nutrient losses. Manage feed delivery routes to prevent cross‑feeding errors between pullet and layer silos. Prevent demixing by limiting fines and adding small amounts of oil when needed, and understand that fine fractions often carry minerals and premix while coarse fractions carry energy. Storage matters, protect silos from moisture and sun, clean when fermentation or mould is suspected, and include antioxidants when oil quality is at risk.

Premix composition and the use of feed additives play a crucial role in supporting flock health and performance. It is important to understand mineral interactions, such as how excess molybdenum or iron can interfere with copper absorption, or the need to balance calcium with magnesium. During periods of heat stress, increasing vitamins E and C can help birds cope, and choline may be partly replaced by betaine to support metabolism. Organic minerals can be used to improve bioavailability or compensate for processing losses. Additives—including probiotics, prebiotics, organic acids, phytogenics, enzymes, toxin binders, and electrolytes—should be selected for specific objectives and evaluated for their economic benefit, rather than used routinely! Dewormers and antibiotics should be reserved for therapeutic use only, as responsible resistance management is essential. Ultimately, a well-designed premix and targeted use of additives can help maintain nutrient stability, optimize bird health, and support consistent production throughout the laying cycle!

Laying hens are exposed to long production cycles and frequent use of by-products, which increases the risk of chronic mycotoxicosis. Because mycotoxin contamination is often patchy, it is essential to take representative samples for analysis. When mycotoxins are detected, use broad-spectrum binders or neutralizers that are matched to the specific toxins and their levels. The latest Nutrition Guide provides practical upper limits for key mycotoxins, with stricter thresholds for rearing and breeders. In addition to mycotoxins, mineral toxicity can also impact flock health and egg quality. It is also important to monitor and respect upper limits for minerals such as chlorine, copper, iodine, iron, manganese, sodium, vanadium, zinc, and potassium, as excesses can lead to health or production problems. Proactive monitoring and targeted interventions are essential to maintain flock health and consistent egg quality throughout the laying cycle.

Sustainability is becoming a central focus in modern egg production, as the industry works to balance efficiency, environmental responsibility, and long-term viability. Key strategies include measuring and reducing the carbon footprint of feed and eggs, increasing the use of circular ingredients such as by-products and alternative proteins, and making careful sourcing decisions to avoid contributing to deforestation or land use change. Precision nutrition plays a vital role by optimizing nutrient use, lowering crude protein and phosphorus levels, and minimizing emissions and nutrient losses to the environment. Extending laying cycles and maximizing the number of first-quality eggs per hen are also important ways to reduce the overall resource footprint. By integrating these approaches, egg producers can meet growing demands for sustainable food while maintaining high standards of flock health and productivity.