Chick quality assessment and incubation optimisation (2)
Part 2: analysis of navels Analysing chick quality is a key factor for the fine tuning of incubation conditions in order to maximize the genetic potential of the hatching eggs. This article focusses on the typical defects observed on the navels of day-old-chicks and how to investigate the cause of the problem in order to optimize chick quality.
Frank Verschuere, Hatchery Development Department, Petersime NV
Commercial hatcheries are operating at a very high capacity. This makes that it is no longer possible to carefully inspect each single day-old-chick. The analysis of chick quality should be done in a controlled way by selecting samples of specific flocks that one wants to investigate. It is important to ensure a consistent and accurate practice of the analysis.
What is a navel?
During the final stages of incubation, many important processes occur such as the blood withdrawal from the CAM (chorioallantoic membrane) and the yolk sac uptake. The navel is the physical point of this vascular and yolk sac retraction.
The navel area is one of the most vulnerable areas for bacterial and fungal infections. An infection can lead to poor post-hatch performance. Therefore it is important that the CAM and yolk sac are fully retracted, which will ensure a clean and well-sealed navel.
Different navels issues
The most common navel issues can be categorized into 4 groups:
- Black button or bruised navel
- ‘String’ navel
- Open and unhealed navel (often with residual yolk)
- Infected navel
Eliminating external factors
Before considering modifying the incubation profile, it is critical to exclude other factors f.e. bad practices of farm management, genetics, egg storage, pre-heating, transfer conditions etc. It is equally important to check technical factors f.e. calibration errors, poor loading or transfer pattern, well-functioning of cooling, heating and ventilation system etc. More information about this can be found in the previous article of this series: “Chick quality assessment and incubation optimisation: Baseline”.
If the poor performance is regional (f.e. a certain area in the machine), the cause is often not related to the incubation program.
Cause of navel issues
Based on the many years of on-site support, it is possible to sum up the most occurring causes of bad navels. It is however impossible to discuss all the possible causes of poor navel quality. Listed below are the most important areas to investigate.
- Black button or bruised navel: The cause is often an incorrect transfer temperature during the late setter cycle or during transfer. An egg shell temperature of 100.0°F is generally optimal. But for young, small eggs it can often result in excessive cooling whilst for very old, large eggs it can results in inadequate cooling due to different volume to surface ratios. Different breeds have different heat production curves and factors as storage conditions, storage time and pre-heating also influence this curve, which requires program modifications.
- ‘String’ navel: The cause is often a poor weight loss and/or excessive cooling during the end of the setter cycle or the early hatching cycle. Excessive spraying after transfer also increases the amount of this defect.
- Open and unhealed navel: The cause is often a late or wide hatch window and a temperature that crossed the correct temperature limits.
- Infected navels: Generally the cause is poor sanitations and/or contaminated/floor eggs combined with the listed causes above. In this case it is advised to check the egg shell quality to be sure that the cause is not a bad egg shell quality.
The navel area is vulnerable for infection and this can influence the post-hatch performance of the chicks. Depending on the navel issue, different incubation related parameters can be the cause. It is however important to eliminate external and technical factors before considering to make changes to the incubation program. Petersime offers frontline support, basic incubation training, advanced hatchery management training and on-site hatchery performance audits to support our customers in every possible way.