INTRODUCTION
This technical document emphasizes the importance of first impressions in the poultry industry, particularly in evaluating chick quality at hatchery and farm arrival. It highlights the need for proper procedures and tools to assess chick quality, ensuring optimal incubation conditions and making necessary adjustments.
The article aims to guide hatchery and farm managers in evaluating chick quality, focusing on three main categories: preincubation, incubation, and post-incubation. The goal is to improve chick quality through careful assessment of each stage, including transport and holding conditions.
INCUBATION FACTORS IMPACTING ON CHICK QUALITY
Temperature: eggshell temperature should be between 100-101°F (37.8-38.3°C) until hatch. Higher or lower than optimal EST will impact on hatchability, incubation time and chick quality (see graph 1). This is the most important incubation factor.
- The EST must be frequently evaluated, and a written procedure should be followed. Optimal body temperature must be followed post transfer to prevent overheating (dehydration) or chilling chicks in hatchers which will impact on chick livability.
- When comparing with multistage setter (MS), single stage can produce better chick quality by maintaining the optimal EST during the incubation period. However, MS can still develop good quality chick when the machine is adequality managed.
Humidity: setter humidity must be set to achieve an egg weight loss (EWL) between 11,5-13,5% at transfer (18,5 days of incubation). Suboptimal EWL impact on hatchability (increase of late dead), chick quality and 7-day livability. Low EWL could produce chicks with a large yolk sac which affect hatchability and increases the risk of bacterial contamination.
It is critical to have a standard procedure to check EWL on a regular basis.
Turning: angle and frequency. Turning failure, suboptimal frequency (more than 60 minutes per turning) or angle (< 38 degrees) have a big impact on hatchability (see graph 2) and chick quality due to a poor development of chorion allantoid membrane, yolk utilization and eggshell temperature uniformity. It is important to regularly check the turning frequency (every day) and turning angle (at least evert 6 months.)
Transfer: transferring hatching eggs from setter to hatcher must be done at the right day (best is 18-19 days of incubation) to maximize hatchability and chick quality. Handling of the eggs is critical to prevent eggshell cracks and must be done fast to prevent the eggs staying for too long at room temperature.
Hatching window: The hatching window is a result from preincubation and incubation factors. The optimal range is between 20 to 28 hours in multistage and less than 18 hours in single stage machines. A long window means that incubation conditions were not uniform (low EST or not uniform ESTs), egg storage was long, egg sizes were not uniform, different parent flock ages, among other factors. This impact on chick quality, chicks become dehydrated, and body weight uniformity. Everything must be done to achieve optimal hatching window.
Pull-out time: Chicks must be pulled out from the hatcher on the right time to prevent dehydration or too green chicks. Both conditions impact on chick livability.
POST-INCUBATION FACTORS IMPACTING ON CHICK QUALITY
1.During chicks processing
Evaluate the different areas during processing that can impact on chick quality. For example, chick counter, beak treatment, vaccine injection, sexing, among others.
2.Holding room and transportation of day-old chicks
Optimal temperature is 20 to 25°C with a relative humidity between 50 to 60%. Constant monitoring of these two parameters is essential and a data logger is the best option for an optimal evaluation.
Optimal ventilation allowing uniform temperature distribution, preventing chilling and overheating.
- Always check vent temperature and behavior.
- The vent temperature should be 104-106°F (40-41°C). Monitor this temperature in each step of processing (pull out, sexing, vaccination, beak treatment, inside chick boxes, etc).
- Transportation must be smooth and shortest as possible. Long transport impact on chick quality and livability (dehydration).
- Clean and disinfected designated trucks (only for day old chicks transport) to prevent infectious diseases.
3.Brooding conditions
Temperature, feed, water, and ventilation are critical to achieve good 7-day livability. Incorrect temperature, wrong feed presentation or quality and lack of access to water will impact on chick quality and livability.
Evaluation of chick quality
- Areas to assess general chick quality and behavior
- Prior or during pull out
- On processing belt
- After sexing
- After vaccination and beak treatment
- In chick boxes prior to delivery
Chicks behavior
At hatchery:
- Do not lay down
- Must be very active
- Chicks should not be noisy. If they are making too much sounds means that they are under some stress (for example, low or high temperature)
At farm:
- Chicks at placement must be very active.
- They must start eating and drinking almost immediately.
There are qualitative, quantitative, semiquantitative and microbiology methods to precisely evaluate chick quality. Regardless of the method to is important to have a good representative sample and must be done after processing and selection.
Qualitative methods
- Behavior (not moving? Laying down, etc)
- Navel quality (black button, string, etc)
- Beak quality (beak treatment, red dot on beak, etc)
- Hocks and leg quality (red lesions, dehydration lesions, etc)
- Abdomen characteristics (is it too big?)
Quantitative methods
- Body weight and uniformity
- Yolk free body mass (YFBM) and Residual yolk (RS)
- Chick yield
- Chick length
- Semiquantitative methods
- Scoring system: Tona, Pasgar or Cervantes
Body weight and uniformity
- 100 chicks per flock (individual weight) after processing and selection
- Important are the uniformity (> 90%) and CV (<8)
Influenced by residual yolk weight, flock age, hatching window and pull-out time - The bigger the yolk the heavier the chicks. This is not always good because a good yolk utilization translates into better immunity, gut health, embryo and chick development
Yolk free body mass (YFBM) and Residual yolk (RS)
- Weight each individual chick and the residual yolk
- YFBM = BW (body weight) – RS
- Optimal YFBM > 90% and goal is to achieve less than 10% residual yolk sac from BW at hatch
- Higher the EST, lower the YFBM and quality
- Good predictor but time consuming and destructive method
Chick yield
- BW of chicks at hatch as a % of egg weight prior to setting (less than 7 days of storage)
- 3 setter trays per flock per machine
- It is not necessary to weight individual chicks but all chicks that hatched from those 3 trays
- Optimal result is between 67 to 68%
- < 67% dehydrated (too much time in hatchers? high 7d mortality? High EWL?) and > 68% too “green” (lethargic, low EWL? prone to bacterial infection)
- This method helps to evaluate chick quality, and at the same time setter and hatcher conditions
Tona, Pasgar and Cervantes Scores
- Semiquantitative methods
- Results could vary among evaluators
- Based on morphological characteristics
- Cervantes metho includes bacterial contamination
- All three evaluate: activity, posture, belly, navel, legs, beak, and eyes
- Pasgar score is more simple and more practical to use
Chick Length
- Good relationship with yolk utilization and less time consuming and destructive method than YFBM method
- Low sample number (25 should be enough)
- Variability between people
- Good method
- It requires to develop your own standard.The optimal length depends on flock age
- It is influenced by incubation conditions and flock age. Weight each individual chick and the residual yolk
- YFBM = BW (body weight) – RS
- Optimal YFBM > 90% and goal is to achieve less than 10% residual yolk sac from BW at hatch
- Higher the EST, lower the YFBM and quality
- Good predictor but time consuming and destructive method
Other evaluation methods
- Hatch analysis and residual breakout. The % of chicks dead on hatcher tray must be 0%
- Cull rate %: less than 0,5%
- Dead on arrival: less than 0.2%
- It is important to measure chick’s vent temperature in different areas of the hatchery: pull out, processing room and holding room.
- A sample of 15 birds is a good number to do the evaluation. The goal is a temperature of 104-106°F. If temperature us lower or higher than the optimal, corrective measures need to be taken 7-day mortality: less than 1%
- Crop fill score: evaluate 100 chicks at 12 hours upon arrival. The goal is to have >95% of chicks with feed in the crop
Chick check (ask technical team for detailed information)
- It is a microbiology method to evaluate chick quality
- Sampling 10 healthy chicks per flock (right after pulling out)
- Yolk swabs for bacterial cultures
- Assess bacteria growth on:
- Blood agar
- McConkey agar: for gram negative
- PEA agar: for gram positive
- Lung tissues for mold (Aspergillus spp) on SabDex agar
- Pool of viscera and intestines for Salmonella culture
- Always evaluate leg, navel, and yolk quality.
- Presence of gizzard erosions
- This method helps to evaluate farm and hatchery sanitary conditions
- A good option is to leave chicks for 48 hours under optimal conditions at the hatchery and after that period take the samples
Big belly is associated with suboptimal incubation temperature and high humidity during incubation. It appears often associated with red hocks.
When too much meconium It is found on eggshells and hatcher trays means that chicks stayed for too long inside the hatchers. Corrective measures must be taken: adjust incubation hours, pull out earlier, evaluate egg shell temperature (maybe is too high) and check incubation humidity (maybe too low).
