Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Animal Science

First Advisor

Michael Gonda


Index, Performance, PRRS, Selection, Swine, Vaccine


Porcine reproductive and respiratory syndrome virus (PRRSV) is the costliest swine disease in North America. Vaccines and management alone have not been effective in controlling this disease. Genetic selection for resilience may be a complimentary approach for controlling PRRSV. The objective of this study was to estimate performance differences between two groups of pigs from the same commercial line following infection with PRRSV 1-7-4: 1) pigs sired by boars selected based on a standard index (TN-S), which emphasized feed efficiency and carcass quality; and 2) pigs sired by boars selected based on an experimental index (TN-E), which emphasized feed intake, piglet vitality, and robustness. Potential welfare and cost concerns of the use of PRRSV 174 to individually infect >1400 animals led to conduction of a pilot study to understand morbidity and mortality of PRRSV vaccinated and unvaccinated pigs. Results showed a 22% mortality in unvaccinated pigs and 5% in vaccinated pigs. Thus, use of PRRSV 174 would provide a robust challenge but vaccination reduces excessive cost and mortality. Pigs (n≅730 per sire group) were housed in a commercial research wean-to-finish barn. Experimental unit was pen, 27 pens per genetic group. All pigs were vaccinated for PRRSV with PRRS MLV at weaning. Four weeks after weaning, all pigs were experimentally infected with 2mL of 1-7-4 PRRSV at 3.5 logs of TCID50/mL. Average daily gain (ADG), average daily feed intake (ADFI), and carcass characteristics were measured. Statistical analyses were performed using a linear mixed model with sire group (TN-S or TN-E) as a fixed effect. The TN-E group had 0.06 kg/day greater ADFI than the TN-S group from 0 to 42 dpi (P=0.01). Feed conversion ratio (FCR) was 0.06 (P

Library of Congress Subject Headings

Swine -- Virus diseases.
Porcine reproductive and respiratory syndrome.



Number of Pages



South Dakota State University



Rights Statement

In Copyright