EFFECT OF PORCINE STRESS SYNDROME GENOTYPE ON THE MATERNAL PERFORMANCE OF A COMPOSITE LINE OF STRESS-SUSCEPTIBLE SWINE

Reproductive data was collected on 61 porcine stress syndrome (PSS) no rmal (NN), 140 PSS carrier (Nn), and 132 PSS positive (nn) composite l ine females farrowing 145, 358, and 362 litters, respectively. Data we re adjusted for parity, number after transfer (pigs cross-fostered 1 t o 3 days after farrowing) and age of litters not weighed exactly at 21 days of age by using established adjustment factors and analysed usin g a mixed-model, derivative-free REML and best linear unbiased predict ion or best linear unbiased estimation procedures fitting the sows' PS S genotype as a fixed effect in the model. PSS-carrier (Nn) females fa rrowed more pigs per litter (p < 0.05) than either normal (NN) or posi tive (nn) females. PSS-NN females had more pigs (p < 0.05) at 21 days than nn females. Litters from PSS-NN females were heavier (p < 0.05) a t 21 days than litters from Nn or nn females. Additionally, PSS-NN fem ales had heavier litters (p < 0.05) at 21 days than nn females. PSS-NN females raised a higher proportion (p < 0.05) of pigs from transfer t o 21 days than either Nn or nn females and NN females had more pigs, h eavier litters and raised a higher proportion of their pigs to 42 days than did nn females (p < 0.05) and a higher proportion i (p i 0.05). PSS-Nn females produced heavier litter raised to 42 days (p < 0.05) th an nn females. The results oT this study indicate that the detrimental effects of the PSS n allele preclude its use in commercial production -maternal lines.