Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Animal Science


Data from 988 pigs from 119 litters farrowed in 2 seasons of a 3-breed diallel crossbreeding and cross-fostering experiment were analyzed to estimate heritabilities, nurse environmental effects, breed effects, specific and general combining abilities of breeds and swine lymphocyte antigen (SLA) haplotype effects on immune response. Partial correlations among immune response traits, growth traits and backfat were also calculated. Purebred boars (20) and sows (85) of the Duroc, Landrace and Yorkshire breeds were used. All 9 breed of sire and dam combinations were represented. Immune response was measured following vaccine challenge. A modified-live pseudorabies (PR) vaccine was administered to piglets at 28 d of age and response measured by log(,2) serum neutralization titers at 56 d. An inactivated Bordetella bronchiseptica bacterin was administered at 28, 42 and 112 d. Antibody levels were measured relative to positive and negative controls at 28, 56 and 119 d using an enzyme-linked immunosorbent assay (ELISA);Heritability was 0.18 for PR titers and was 0.15 and 0.52 for 56- and 119-d ELISA values, respectively. The variability due to nurse environment as a percent of phenotypic variance was 11.1% for PR titer and 29.6% and 8.8% for 56- and 119-d ELISA values, respectively. No specific combining abilities or breed maternal effects were observed. Pigs testing positive for the a SLA haplotype had higher (P < .10) immune response to B. bronchiseptica vaccine at 119 d. Higher immune responses to B. bronchiseptica vaccine were generally associated with slower gain. Partial correlations of days to 100 kg. with 56- and 119-d ELISA values were 0.15 and 0.12 (P < .01). There was no significant correlation between backfat thickness and immune response.



Digital Repository @ Iowa State University,

Copyright Owner

David Lynn Meeker



Proquest ID


File Format


File Size

110 pages

Included in

Genetics Commons