Fig. 2

Predicted stayability and litter size in first and second parities. Predicted probability (with 95 % CI) of a sow producing ≥4 litters in her lifetime (y-axis) for different exposure groups based on combined categories of first and second parity litter size (x-axis): S small litter size (≤11 piglets), M medium litter size (12–14 piglets), L large litter size (≥15 piglets), 1 first parity and 2 second parity. Predictions are from multivariable logistic regression including exposure group, birth year of the sow and age at first farrowing as explanatory variables and herd as a random variable. Data were selected from January 1 1997 to December 31 2009 from 24 Swedish piglet producing herds and included 32,300 observations