Extreme crowding in laying hens during a recurrent smothering outbreak

Area of Science:

• Animal behavior
• Poultry science
• Animal welfare

Background:

• Hen piling, or smothering, is a significant welfare issue in the egg industry causing mortalities.
• This behavior is understudied despite its economic and ethical implications.

Purpose of the Study:

• To describe extreme hen piling behavior during an outbreak.
• To investigate potential associations between piling and flock productivity and health indicators.

Main Methods:

• Continuous video recording of a commercial, free-range flock over 35 days during a smothering outbreak.
• Quantification of piling events, bird density, and location regularity.
• Analysis of associations with productivity and flock health metrics (water:feed ratio, temperature range).

Main Results:

• Forty-eight piling events were documented, with densities up to 187.93 birds/m² and over 1200 birds per pile.
• Piling behavior exhibited regularity, occurring in the same location on most observation days.
• No association was found between piling extremity and productivity, but significant links to water:feed ratio and temperature range were identified.

Conclusions:

• This study presents the most extreme hen piling event reported in scientific literature.
• Findings offer novel insights into the regularity and environmental correlates of this detrimental poultry behavior.
• Understanding these factors is crucial for mitigating smothering events and improving hen welfare.