Does giving animals’ control of their own thermal environment improve welfare?
In animals, thermal environment in early life can shape behavioural, cognitive and physiological development. This sets individuals on different lifelong welfare trajectories. While mechanisms for thermogenesis mature, neonate birds (‘chicks’) are dependent on the parent for brooding. A better understanding of the thermal preferences of commercial species, and the consequences of these for downstream welfare, offers scope to inform fine-scale environmental control in farms. This is increasingly tractable within Precision Livestock Farming (PLF), and has scope to improve not only welfare, but energy efficiency, with direct economic and environmental benefits.
In nature, chicks of precocial poultry and game species call to elicit brooding by the parent amongst bouts of activity. Consequently, they have 1) experience of varying temperatures in early life and 2) scope for behavioural control of thermoregulation. This is in contrast to commercial systems, where whole-house heating is usually applied and optimised on a daily temperature informed by flock-level production data (e.g. growth rate, mortality). These optima are necessarily based on the average chick, and may not capture thermal requirements of those at the extremes with different energetic costs (e.g. smaller size, poorer health status, higher stress). Given the choice of a thermal gradient, naturalistic thermo-temporal patterns emerge: chicks rest in higher temperature zones and move into lower temperature zones during activity/foraging. This suggests potential energetic and welfare benefits of a more naturalistic thermal regime. This may either be via experience of temperature fluctuation per se, or by affording the animal greater control.
However, the downstream impacts of temperature fluctuation are under-researched. Each year, 800 million chicks (chicken, turkey, geese, game) in the UK, and over 17 billion around the world, may therefore live in sub-optimal thermal environments.