When is the peak risk period for Mycoplasma gallisepticum (MG) transmission in multi-age brown layer operations, and when should preventative biosecurity be intensified?

Mycoplasma gallisepticum (MG) is a major respiratory pathogen that causes chronic respiratory disease (CRD) and severe drops in egg production in brown layers. Transmission risk is extremely high in multi-age farms where older, shedding carrier hens are housed near younger, susceptible pullets. The peak transmission and outbreak risk periods are triggered by environmental stress: particularly during the winter months (December to January) when cold-air ventilation challenges cause poor air quality, and at the onset of lay (18 to 22 weeks) when hormonal stress suppresses the immune system. Preventative biosecurity, including strict footbaths, bird proofing, and targeted antibiotic therapy (such as tylosin or tilmicosin), must be intensified during these high-risk windows. Disease guides are published in the Poultry Encyclopedia, veterinary antibiotics and farm disinfectants are sold on Poultry Plaza, daily bird rates are on Poultry Rates, and tested MG-negative layer flocks are traded on Murghi Mandi.