Residual yolk sacs tell the story behind a flock’s early life management. Measuring residual yolk sacs can provide information that you can use to improve your practices for future flocks.
Can you improve your operation by checking yolk sacs? Yes, you can!
Residual yolk sacs tell the story behind a flock’s early life management. The lipids (fats) contained in the yolk are the primary energy source during the second half of egg incubation and the early post-hatch period. At approximately 19 days of incubation, the yolk is actually internalized in the abdominal cavity of the developing chick and will provide nutrients to the chicken for up to 5 days after hatch.
Providing feed early and optimal housing conditions during the first week of life will support maximum absorption of the yolk which will also support a healthy and robust immune system. The presence of any stressors such as low barn temperatures, malnutrition, noise stress, poor handling conditions, low-quality drinking water, and any discomfort during the first week of the chick’s life can result in reduced yolk absorption by the chick. This could lead to decreased immune status and/or abnormal health conditions in the flock.
Recording yolk sac residual sizes is tool that can be used to link bird conditions and management to performance. If you experienced lower performance than expected and a higher than expected number of birds with larger than expected yolk sac residue, you can inspect your records to determine what might have caused the issue, fix it, and be prepared for the next flock.
So what should you look for? The residual yolk sac is located at Meckel’s diverticulum in the small intestine (pictured here). This location is where the chick drew in the nutrients from the yolk during incubation. Image credit to Avian Digestive System
A “normally” absorbed yolk sac is about the size of a lentil in broilers. If the yolk sac residue is bigger than a lentil, it is a signal for you to inspect your records from the first week of the flock’s life. Did a heater fail and the chicks got chilled? Was there an interruption to the feed supply? Were you working with loud equipment near the barn?
Keeping track of residual yolk sac size is not a silver bullet, but it is a useful tool to enlighten the future management decisions. In conjunction with a robust record keeping system, you will be able to continually improve your systems to support the health and productivity of future flocks. The yolk sac can also be a helpful report card – if you’re finding mostly normal sized yolk sacs you’ll know you’ve done a good job during that critical first week of life.
References:
- van der Wagt, I., de Jong, I. C., Mitchell, M. A., Molenaar R., and H. van den Brand. 2020. A review on yolk sac utilization in poultry. Poultry Science. 99:2162–2175.
- Wang, J. S., Hu, H. J., Xu, Y. B., Wang, D. C., Jiang, L., Li, K.X., Wang, Y. Y., and X. A. Zhan. 2020. Effects of posthatch feed deprivation on residual yolk absorption, macronutrients synthesis, and organ development in broiler chicks. Poultry Science. 99: 5587–5597.
Mohammad was the PIP team Research Associate (2021-2024) with extensive experience in poultry nutrition. He wrote science articles for newsletters and worked on developing adaptations and recommendations to support the adoption of new managerial tools, products, services, and practices by the poultry industry.
Looking at his poultry industry perspective, Mohammad has been serving the poultry industry through his extensive experience in feed formulation as an animal nutritionist over the past ten years. He was also a university lecturer for 10 years. Mohammad was a member of the Animal Care and Use Committee (ACUC) at the U of A. Mohammad graduated with a Ph.D. degree in Animal Science from the University of Alberta with a Postdoctoral fellowship before moving to his Research Associate position with the PIP team. Serving the poultry industry as an animal nutritionist for more than a decade, Mohammad loves teaching and worked as a university lecturer in Iran and a teaching assistant at the U of A. Mohammad was inspired by Dr. Frank Robinson, practicing the inquiry-based learning method when working as a TA in his “Principles of Animal Agriculture” class. “I have a strong passion on poultry nutrition and have always loved to help poultry producers with optimizing the poultry systems. The challenging part of working with live animals is that you need to be on call even as a nutritionist. However, the joy of seeing healthy animals and help with their welfare overcome the challenging part.”
