A composite sow index and its effects due to sire, parity and season

Abstract

A composite sow index of the form I = c + a₁x₁ + a₂x₂ + a₃x₃ + a₄x₄ + a₅x₅ + a₆x₆ was worked out by considering the characters, viz. age at farrowing (X₁), post weaning conception period (x₂), litter size at birth (x₃ ), average weight of a piglet at birth (x₄), litter size at weaning (x₅)' average weight of a piglet at weaning (x₆). The weighting coefficients ai's are worked out by considering the normal pdctice and other experience. Based on this index, the most efficient sows were identified. Further this index can be advantageously used for selection of the uneconomic animals for culling. Attempts were also made to find the sire effect, parity effect and seasonal effect on pigs based on this index.