Lifetime and per year productivity of sows in four pig farms in the tropics of Mexico.

The objectives of this study were to estimate the lifetime and per year productivity of sows and to determine the effect of some factor on those traits in four pig farms in the tropics of Mexico. Data from 7526 sows for lifetime number of piglets born alive per sow (LBA), lifetime kilograms of piglets at farrowing (LKF), number of piglets born alive per year (NPF/Y), and kilograms of piglets at farrowing per year (KPF/Y); and data from 7230 sows for lifetime number of piglets weaned (LPW), lifetime kilograms of piglets weaned (LKW), number of piglets weaned per year (NPW/Y), and kilograms of piglets weaned per year (KPW/Y) per sow were used. The statistical model for all traits included the fixed effects of farm, year of first farrowing, season of first farrowing, litter size at first farrowing, age at first farrowing, removal reason, simple interactions, and the error term.