Survival, mortality and disposal patterns of Salem Black goats: a 35-year longitudinal study

Mortality and poor survivability remain major constraints limiting productivity and profitability in goat production systems, particularly under intensive management conditions. This study evaluated survival patterns, mortality trends, and disposal dynamics in Salem Black goats using longitudinal data collected over 35 years (1987-2022) at the Mecheri Sheep Research Station, Tamil Nadu, India. After data cleaning, records from 2,433 animals were retained for analysis. Survival time was defined as the interval from birth to death or disposal, with death considered the event of interest and sale or transfer treated as censored observations. The overall mean survival time was 584.3 ± 652.1 days, indicating considerable variation in longevity among animals. The overall mortality rate was 21.17%, whereas 77.81% of the animals were disposed of through sale, reflecting the economic orientation and planned herd management strategy of the production system. Mortality declined markedly across successive production periods, decreasing from 42.85% during 1987-1992 to 3.03% during 2018-2022, suggesting substantial improvements in herd health management, disease prevention, nutrition, and veterinary care. Enteritis (17.48%) and pneumonia (10.29%) were the leading causes of mortality. Kaplan-Meier survival analysis showed a gradual decline in survival probability with increasing age. Cox proportional hazards regression revealed that the production period significantly influenced mortality risk, whereas sex and season of birth had no significant effects. These findings indicate that long-term improvements in herd management and health practices can substantially enhance survival, productivity, and the sustainability of organized Salem Black goat production systems.