Poultria is a free, open-access digital academy and decision-support platform for poultry science, disease diagnostics, least-cost feed formulation, and farm management.

How to calculate EPEF in poultry?

European Poultry Efficiency Factor (EPEF) is calculated as: [Livability (%) × Body Weight (kg) × 100] / [Age in Days × FCR]. Scores above 400 indicate top commercial performance.

Is Poultria free for university courses?

Yes, Poultria provides 100% free open access for all university courses, veterinary faculties, and student researchers worldwide.

Marek's Disease in Chickens: Paralysis & Lesions

Veterinary Reviewed

Marek's Disease: Sciatic Paralysis & Lymphoid Neoplasia

Technical guide on Gallid alphaherpesvirus 2 pathogenesis, grey eye, and Rispens vaccination.

Scientific Overview

Marek's Disease is an oncogenic (cancer-causing) viral disease of young chickens, caused by Gallid alphaherpesvirus 2 (MDV). It causes neoplastic transformation of T-lymphocytes, leading to progressive lymphoid tumors in visceral organs and demyelination of peripheral nerves.

Sciatic Nerve Paralysis & Classical Symptoms

MDV is highly stable in dust and feather dander, spreading rapidly via inhalation. The classic clinical sign is progressive paralysis, showing a typical posture with one leg stretched forward and the other backward, caused by sciatic nerve demyelination. Other symptoms include wing droop, weight loss, iris depigmentation ('grey eye'), and irregular pupillary margins.

Visceral Lymphomas and Prevention

Necropsy reveals marked enlargement and loss of striations in peripheral nerves (sciatic, vagus, brachial plexuses), and gray-white lymphoma tumor nodules in the liver, spleen, kidneys, heart, lungs, proventriculus, and muscles. There is no treatment. Flocks must be vaccinated in-ovo (Day 18 of incubation) or subcutaneously at hatch with HVT or Rispens strains.

school Verified Peer-Reviewed Academic Citations & Literature Standards

All scientific data, diagnostic criteria, and performance benchmarks presented on this page are derived from published peer-reviewed journals and official veterinary codes:

Avian Pathology & Diagnostics: World Organisation for Animal Health (WOAH, 2023). Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. Paris, France.
Poultry Diseases & Histology: Swayne, D.E., et al. (2020). Diseases of Poultry (14th ed.). Wiley-Blackwell / American Association of Avian Pathologists.
Nutrition & Feed Chemistry: Leeson, S. & Summers, J.D. (2001). Commercial Poultry Nutrition (3rd ed.). University Books, Guelph, Ontario.
Commercial Breed Standards: Aviagen (2024). Ross 308 & Cobb 500 Broiler Performance Objectives. / Lohmann Breeders (2024). Lohmann Brown Management Guide.