The transition of cattle and sheep between indoor housing and pasture in spring and autumn represents a welfare risk point that requires careful management to prevent digestive and metabolic problems.
Seasonal pasture transition welfare is a critically important management period that receives less attention than it deserves given the significant acute welfare harms that can occur if transitions are poorly managed. Spring turnout of dairy cows to lush grass, if unmanaged, can cause hypomagnesaemia (grass staggers) within hours - a condition causing neurological symptoms including muscle tremors, falling, and death if untreated. The calcium and phosphorus imbalances of early spring grass can also trigger milk fever (hypocalcaemia) in high-yielding dairy cows. Bloat from fermentation of fresh grass produces gas accumulation that can be life-threatening within hours. All of these acute welfare harms are largely preventable through gradual transition management: starting with limited access to pasture of 1-2 hours daily, increasing over 1-3 weeks while monitoring individual animal response, and ensuring adequate mineral supplementation. The behavioural eagerness of housed animals to access spring pasture after winter confinement - running, jumping, and playing - while welfare-positive, must be managed to prevent injuries and facilitate the controlled dietary transition that prevents metabolic disease.