Use of a Stochastic Model to Evaluate the Growth Performance and Profitability of Pigs from Different Litter Sizes and Parities of Dams

A stochastic model was developed to evaluate the effects of total number of pigs born and dam parity on pig compositional growth and postweaning profitability. The survival of pigs was modeled as a function of parity and of birth weight. Two management strategies were simulated, either with or without cross-fostering. Without cross-fostering, litter sizes of 6 to 14 total pigs born were simulated. Litter sizes of 6 to 20 total pigs born were simulated to be cross-fostered to obtain a constant of 11 pigs nursed. Pigs from parity 1 dams were predicted to be slower growing and have reduced survival compared with pigs from dams of other parities. Increasing total pigs born from 6 to 14 without cross-fostering reduced 150-d BW by 8.0 kg and carcass weight at marketing from 5.8 to 6.2 kg. Differences in carcass value from 6 to 14 total pigs born ranged from $9.50 to $11.10 per pig and profitability of pigs ($/weaned pig) ranged from $6.17 (parity 6) to $7.37 (parity 1). Without cross-fostering, weaning pigs from parity 1 dams were $5.82 to $7.68 less valuable than pigs from dams of other parities at the same total number born. Pigs born and reared in cross-fostered litters by parity 1 dams had $9.72 and $10.09 less carcass value and were $6.70 and $7.06 less profitable than weaning pigs of parity 2 and parity > 3 dams. Pigs born in larger litters, with or without cross-fostering, were less profitable postweaning than pigs from smaller litters.