Embryology Guide: Developmental Stages of Pekin and Mulard Ducks

Incubation & Embryology
Written By Jennifer Bryant

Research Review

Pekin and Mulard duck embryos do not develop on identical schedules. This 2025 study mapped their development from the first hours of incubation through hatch, giving breeders a more accurate guide for candling, breakout diagnosis, and hatch-timing expectations.

Source Paper

Trela, M., Sołtysik, W., Kustra, K., Januszewska, A., & Lis, M. W. (2025). “Developmental stages of the Pekin duck (Anas platyrhynchos f. domestica) and the Mulard duck in artificial incubation.” Poultry Science, 104(8), 105132. Read the original research: https://doi.org/10.1016/j.psj.2025.105132

Why This Paper Matters

Chicken embryo charts are often borrowed for waterfowl, but calendar day alone can be misleading. A normally developing Mulard embryo may look delayed when judged against a Pekin chart. Breed-specific staging helps separate a true developmental problem from a normal difference in timing.

Study at a Glance

  • Species: Domestic duck and mule-duck hybrid

  • Breed or line: Pekin (Cherry Valley) and Mulard

  • Eggs: 1,800 per group; 3,600 total

  • Location: Poland

  • Journal and year: Poultry Science, 2025

  • Incubation period: About 28 days for Pekin and up to about 32 days for Mulard

How the Study Was Conducted

Researchers followed both groups under artificial incubation using the same repeated sampling framework. Temperature gradually decreased from 37.8°C to 36.2°C, while relative humidity declined from 65% to 60%. Embryos were sampled every six hours early, every 12 hours during the middle period, and daily later in incubation. The team recorded morphology, Hamburger–Hamilton stage, candling removals, mortality timing, pipping, hatchability, and breakout findings.

Key Findings

  • Pekin embryos developed faster beginning on the first day of incubation.

  • Mulard embryos remained later on the developmental clock and took longer to reach hatch.

  • Pekin mortality peaked around days 2–3 and again around days 22–26.

  • Mulard mortality peaked around day 4 and again from days 24–30, with a sharp rise near external pipping.

  • The developmental differences were large enough that Pekin and Mulard eggs should not be evaluated with one shared calendar-day chart.

Practical Application

When candling or performing an egg breakout, record both the calendar day and the embryo’s visible stage. A Mulard embryo that appears behind a Pekin embryo may still be normal. Use the appropriate timeline when judging development, and pay special attention to each group’s late-mortality window and expected external-pip timing.

Strengths of the Study

  • Large hatch cohorts began with 1,800 eggs in each group.

  • Both groups were studied with the same repeated sampling and hatchery framework.

  • The paper combined detailed morphology with hatch records and mortality distributions.

  • The staging descriptions have direct value for candling education and embryo-breakout diagnosis.

Limitations of the Study

The work applies to the tested Pekin and Mulard lines and their commercial incubation program. Muscovies, Call ducks, heritage ducks, geese, swans, and other hybrids were not tested. Only three embryos per group were examined at each individual sampling time, and the study ended at hatch rather than following long-term health or reproductive performance.

Poultry Nerds Takeaway

Teach Pekin and Mulard embryology with separate timelines. A calendar day is useful, but morphology tells you where the embryo actually is. Breed-specific expectations make candling more accurate, improve breakout interpretation, and reduce the chance of mislabeling normal Mulard development as delayed.

Continue the Incubation Research Cluster

Research Review Notice

This article summarizes a peer-reviewed scientific publication and explains its practical application for poultry keepers, breeders, and educators. It is an original review written by Poultry Nerds, not a reproduction of the manuscript. Findings apply to the species, lines, conditions, and outcomes evaluated by the researchers; additional research may support, refine, or contradict these findings.

Jennifer Bryant
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