Keys to Reducing Mortality in the First Week of Broiler and Laying Hen Chicks

The first week of a chick's life is critical: it represents almost 20% of its productive lifespan (1), and a good quality bird with optimal management should not exceed 0.7% mortality in that period.

ANIMAL PRODUCTION

8/27/20258 min read

The first week of a chick's life is critical: it represents almost 20% of its productive lifespan (1), and a good quality bird with optimal management should not exceed 0.7% mortality in that period (2). Most deaths in the first 3–4 days are linked to the quality of the chicks upon arrival (3), while later deaths are related to on-farm management. Quickly recognizing signs of weak chicks and immediately removing carcasses is essential to minimize losses (3, 4). Below are the most common causes, warning indicators, and preventive practices based on technical sources (Aviagen, Ross, AviNews, INTA, etc.).

Common Causes of First-Week Mortality

Thermal Stress and Chilling: Newborn chicks lack thermoregulation; a suboptimal ambient temperature (especially cold) increases mortality, as chilling causes them to lose appetite and immunity (2, 5). A wet floor or drafts worsen the cold through the bird's feet (6, 7). Conversely, excessive heat can also cause dysregulation or sudden death.
Dehydration and Starvation: Delays in removing chicks from the hatcher or in their arrival at the barn lead to weight loss from evaporation, especially in chicks from young breeder hens (8). Each additional hour in the hatcher increases weight loss by ~0.4–0.5% if body temperature drops (8, 9). On the farm, a lack of quick access to water and feed results in starvation: in the first few days, a chick consumes about twice as much water as feed (10), and without eating for 24–48 hours, intestinal and immune development is delayed (11).
Omphalitis (Navel Infection): Omphalitis—inflammation/infection of the navel and yolk sac—is a frequent cause of peak mortality between days 5–7 (12). It presents as "soft" chicks with fever and a swollen abdomen; it often occurs when cracked eggs or dirty hatcheries allow bacteria (coliforms, Staphylococcus, etc.) to enter the yolk sac (13, 14). Losses from omphalitis can reach 5–10% in affected batches (12).
Incubation and Transport Management: Incubation with out-of-range temperatures or humidity generates chicks with poorly closed or underdeveloped navels, predisposing them to omphalitis and low viability (15, 16). Very wide hatch windows (prolonged waiting in the hatcher) dehydrate chicks and reduce their uniformity (8, 17). During transport and handling, bumps or cold drafts can cause suffocation or shock; containers should be at ~32°C and 65% RH, avoiding direct air currents on the birds (9, 18).

Risk Indicators and Flock Monitoring

To detect early problems, successful farms monitor several indicators:

Crop Fill (Feed/Water Intake): 1–2 hours after housing, crop fill is evaluated in a sample of birds (19). It is expected that >75% of chicks have a full crop at 2 hours, >95% at 24 hours, and 100% at 48 hours (20). An empty or nearly empty crop indicates a failure in feed availability or environmental problems.
Water Consumption: Water must always be clean and available. In temperate conditions, the water-to-feed ratio is ~2:1 (it can be higher in hot weather) (10). It is recommended to chlorinate the water to 3–5 ppm and disinfect the lines between flocks (21). Sudden drops in water consumption (or excessive thirst) can indicate thermal stress or illness.
Body Weight and Uniformity: It is recommended to weigh sample birds daily. Chicks should quintuple their initial weight in 7 days (22). Uniformity (low coefficient of variation) reflects stability; values below 8–10% CV in the flock indicate good uniformity. 65% of the variability in first-week mortality is explained by the quality of the received chick (23), so evaluating weight and dispersion at 7 days helps detect early-stage problems.
Cloacal Temperature: This is a practical indicator of thermal comfort. The rectal/cloacal temperature of at least 0.5% of the flock should be measured in different areas of the barn, preferably during the first 4–5 days. The optimal value is 39.4–40.5 °C (24, 25). Lower body temperatures suggest ambient cold; very high temperatures indicate overheating. The feet should also be checked: if they feel cold to the touch, the floor or ambient temperature is likely low (26).
Behavior and Distribution: The birds should be distributed uniformly under the brooders and vocalize normally. If they huddle under lamps or near the walls, it may be cold; if they move away from heat sources with agitated breathing, there is too much heat (27). Direct observation (sight, sound, smell) of the chicken house completes the environmental assessment.

Barn Receiving Protocol

When the chicks arrive, it is essential to provide them with a prepared environment:

Barn Pre-heating: Heat the barn at least 24 hours before arrival to equalize the temperature of the floor litter (28, 29). Maintain about 30°C at bird level on the first day (for broilers; similar for pullets), with relative humidity ~60–65% (5). The litter temperature should be monitored directly, as chicks "take" heat through their feet (30). The starting areas need specific caloric input (brooders or mats), without excessive drafts (speed <0.2 m/s under brooders) (31).
Lighting and Photoperiod: Provide at least 23 hours of continuous light (30–40 lux) during the first 7 days (32). A minimum of one hour of darkness (0.4 lux) helps prevent stress, allows for rest, and helps detect anomalies. Distribute light uniformly (>25 lux with no dark areas) so that all birds can see water and feed (32, 33). After 7 days, the darkness period can be progressively increased to 4–6 hours.
Stocking Density: The initial density depends on the available heating power. In general, 40–45 chicks/m² is recommended upon entry (34). If using fenced-off brooding areas in the barn (half-lots), start with enough space and then expand after 7 days.
Ventilation and Air Quality: Maintain a gentle airflow (constant air exchange without cold drafts) to remove ammonia and moisture without causing a wind chill effect on the birds (35). Fans should not be aimed directly at the chicks. In this initial phase, ventilation is for air renewal (low sensible heat exchange), not for cooling.
Starting Litter: Use clean, dry, and disinfected litter. Wet or soiled litter increases the risk of chilling through the feet and infections. A minimum layer of 5–8 cm of good insulating material (shavings, sawdust) is recommended to insulate the floor (36). Additionally, starter paper covers the floor to facilitate initial consumption and keeps the litter clean for the first few days (37).

Initial Feeding Management

Proper nutritional startup boosts flock consumption and vigor. Recommended practices include:

Give chicks access to feed on paper immediately upon arrival at the barn (37). Place feed in flat trays (one for every 100 birds) or directly on paper covering 80–100% of the starting area (37, 38). The trays or paper should never run out of feed: add more frequently during the first 3–4 days to maintain a continuous supply (39). Use a high-quality, easy-to-digest starter feed (coarse meal or crumbles), as newly hatched chicks prefer large, visible particles (10). A water-to-feed ratio of ~2:1 is suggested from day one (10). Fill drinkers and lines with fresh water (5–25 °C) to encourage intake, remembering that chicks drink about 65 mL/bird in the first 24 hours (10, 40). Correct management of feeders and drinkers—adjusted height, no leaks or blockages—is essential.

Personnel Management, Biosecurity, and Vaccination; Day-Old Chick Quality

Biosecurity and Cleaning: Adopt the "all-in, all-out" principle: all flocks should be single-aged, with a complete cleaning and disinfection of the barn, equipment, and vehicles before each new arrival (41, 42). Before entering the barn, personnel must disinfect their hands and wear clean boots; only visit with farm-exclusive clothing. Maintain high hygiene standards at the hatchery and during transport: transporting chicks quickly in clean, protected boxes prevents stress and contamination (9, 42). Successful operations measure the post-cleaning bacterial load (total counts, Salmonella, E. Coli) to validate the effectiveness of disinfection (43).
Vaccination: Ensure that pullets or broilers are vaccinated according to the recommended program (Marek's, Newcastle, Bronchitis, Gumboro, Coccidiosis, among others), either at the hatchery (injection or spray) or on the farm. Each bird must receive the correct dose. Vaccination in comfortable weather and under vaccine quality standards reinforces initial immunity.
Chick Quality: The quality of the day-old bird (body weight, hydration, clean navel) directly influences subsequent mortality. Studies show that ~65% of first-week mortality is associated with initial chick quality (23). Evaluate at least 10–20 sample birds upon arrival: check weight (minimum target according to genetics), absence of deformities, good hydration, and a healed navel. A bloated or black navel indicates a risk of infection. The Cervantes score (0 to 100) is a standardized method for evaluating individual quality (44). In case of low quality, contact the hatchery.
Training and Protocols: Staff must be trained to recognize early symptoms of disease or management failure. Keeping daily records of feed/water consumption, weight, and mortality helps detect negative trends. Following stage-by-stage management guides (e.g., Ross or Cobb) standardizes the response to variations in productive parameters.

Preventive and Corrective Measures Used on Successful Farms

Operations with low mortality share strict preventive practices and rapid actions when problems are detected:

Pre-incubation and Hatchery Hygiene: Exhaustive hygiene of nests and breeder houses, and of the incubators after each batch, is performed (45). Eggs are prevented from arriving wet or cracked; hatcher trays are dried and rigorously disinfected (45). If cracked eggs are identified, the equipment can be fumigated before starting a new batch (45). The goal is to produce chicks with a clean, almost closed navel (46). Hatching areas are kept at optimal temperature and humidity to prevent navel malformation and favor a quick hatch.
Control of the Hatch Window and Immediate Management: A hatch window that is as short as possible is sought (8). It is advisable not to remove chicks from the incubator until most are dry, to avoid leaving late-hatching ones in the hatcher (risk of dehydration) (17). Upon arrival, chicks are quickly placed in brooders with optimal climate conditions (31–32 °C in the brooding area) (9, 47). In many cases, drip drinkers are added in the hatcher during transport to stimulate early hydration.
Intensive Nutritional Startup: Initial intake is encouraged to the maximum: covering the entire area with feed on paper, many water sources, and bright lighting. Sometimes water is supplemented with electrolytes or vitamins in the first 24 hours to counteract travel stress. It is monitored to ensure that at least 80–90% of the chicks have a full crop after 4–8 hours of arrival (20). If this is not achieved, immediate corrective actions are taken (e.g., temperature review, increased light, density adjustment).
Continuous Monitoring and Adjustment: Successful producers perform frequent weigh-ins and analyze uniformity. If mortality rises above the norm (<0.7% in the first week) (2), the cause is sought: necropsies of the dead (to differentiate omphalitis, respiratory, or metabolic problems) and review of sensors (temperature, humidity). Based on this, ventilation, brooder height, or water management are adjusted. For example, if many chicks appear with cold feet or cloacas, the focal heat is increased; if acidosis from cold appears, the ambient temperature is raised.
Infrastructure Maintenance: Post-flock hygiene is performed (deep cleaning of drinkers, feeders, water system, and barn) as a routine practice. Aviagen recommends chlorinating water to 3–5 ppm and applying specific disinfectants to the drinking lines (21). Electrical and heating systems are also checked before each cycle.

Together, these actions—based on recommendations from genetic companies (Ross, Aviagen, Cobb, Hy-Line) and technical institutions (INTA, universities)—ensure that chicks start their lives in optimal conditions. Rigorous management of the environment, feed, and biosecurity during the first week minimizes initial deaths and sets the foundation for a healthy and productive flock.

Sources: Technical manuals from Ross, Aviagen, and Hy-Line, specialized articles (aviNews, ElSitioAvícola, Engormix), and newsletters from poultry companies (Pas Reform, Cobb, etc.) (2, 37, 41, 45, 48). These references support the points made and provide practical, evidence-based guides.

(1, 18, 28, 30, 33, 34, 35, 38, 40) Manejo de Recepción de un Pollo de Engorde

https://www.abcavicola.com/post/manejo-de-recepci%C3%B3n-de-un-pollo-de-engorde

(2, 9, 16, 25, 36, 41, 42, 43) images.proultry.com

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(3, 4) Mortalidad en Aves: Causas y Control

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(5, 6, 7, 29, 31) El manejo en la primera semana de vida del pollo de engorde - aviNews, la revista global de avicultura

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(8) Nacedoras: Deshidratación del pollito y otros problemas en la nacedora

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(10, 11, 22) Nutrición de pollos de engorde durante la primera semana - aviNews, la revista global de avicultura

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