The nursery phase — from weaning (typically 3-4 weeks of age) to approximately 30kg — is the highest welfare-risk period in commercial pig production. Weaning is a profound physiological and psychological stressor: pigs are simultaneously separated from their mother, mixed with unfamiliar animals, moved to a new environment, and transition from milk to solid feed. Managing this period well is fundamental to lifetime welfare and performance.
At weaning, pigs experience multiple concurrent stressors: social disruption, loss of maternal contact, unfamiliar environment, and dietary transition. Plasma cortisol surges at weaning; immune function is temporarily suppressed. This vulnerability window is when the most significant health challenges occur. Management strategies that reduce the severity of weaning transition improve welfare outcomes throughout the nursery phase.
Post-weaning diarrhoea (PWD) caused by enterotoxigenic E. coli (ETEC) is one of the most significant welfare and production challenges in the nursery. It causes acute suffering, dehydration, and significant mortality without treatment. Prevention strategies include:
Enzootic pneumonia (Mycoplasma hyopneumoniae) and Porcine Reproductive and Respiratory Syndrome (PRRS) are significant welfare concerns in nursery pigs. Adequate ventilation (avoiding draughts while maintaining air quality), temperature management (28-30°C for newly weaned pigs, reducing with age), and appropriate biosecurity are essential preventive measures.