Fewer total pigs born suggest reduced embryo survival in early pregnancy (Dial et al., 1992) or lower ovulation/fertilization rates. Our results showing few total pigs born may indicate increased embryo mortality or decreased ovulation/fertilization rates in females susceptible to stressors. For example, high ambient temperature adversely affects embryonic survival after breeding (Edwards et al., 1968). Like high temperature, exposure to the stressors of feed restriction and confinement during early gestation may affect low embryo survival (Friend et al., 1988) in some females, although we did not measure physiological stress indicators, such as glucocorticoids (Zanella et al., 1998), in stalled females