Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Animal Science

First Advisor

Kenneth J. Stalder


Sow productive lifetime continues to challenge U.S. commercial swine herds and worldwide pork operations in general. The increased prevalence of hoof abnormalities (e.g. hoof and dew claw overgrowth, hoof wall cracks, and foot pad abrasions) in cull sow populations observed at harvest lend evidence to the hypothesis that these abnormalities are detrimental to sow performance. The objectives of this thesis were four-fold. The first objective was to summarize sow behaviors associated with increased sow welfare productive lifetime, specifically maintenance (feed and drink), social (aggression, sow-piglet interaction, and expression of sexual behaviors), and stereotypical behaviors. Results from this review suggest that detrimental behaviors were stereotypical behaviors such as bar bitting, aggression between sows through lower feed intake, aggression toward caretakers, and piglet savaging and cannibalism.

The second objective of this study was to evaluate the effects of excessive toe growth, presence of cracks in the outer hoof wall, and the difference in length between the medial and lateral toe of the hoof on lactation performance and sow behavior in mid-lactation. This study concluded that sows with overgrown toes stand less than sows with normal hooves, and those findings are consistent with other studies. Sows were observed standing and eating between 3.3 and 9.1 % of the observation period, and, of the variables collected, eating was the primary activity performed while standing. Post feeding, each OG lesion score increase was associated with a 40.0 % decrease in time spent standing and eating. This observation held true for total time spent standing and eating during the observation period [Odds Ratio (OR) = 0.45]. Results from this study demonstrate that foot lesions can impair productivity and behavior of lactating sows. The degree to which foot lesions impair production and behavior is dependent on lesion type and severity.

The third objective of this study was to estimate observer accuracy and repeatability of body condition scoring sows when scorers have different levels of prior experience. Participants body condition scores were positively associated with body condition scores (BCS) derived by backfat measurements. Averaging over all participants, the ultrasonic trait of last rib backfat yielded the greatest correlation (0.58) with BCS using a 9-pt scale, followed by tenth rib backfat (0.51), tenth rib loin eye area (0.47), and last rib loin eye area (0.43). Similar trends were observed for the BCS5 scale. Therefore, practice assigning independent BCS should lower repeatability variance, but training to calibrate specific participants may only influence total test variance to a relatively small degree.

The final objective of this study was to estimate the amount of feed and associated costs of adding body weight to cull sows, in an evaluation to improve producer profitability. Adding BW to cull sows could be profitable in the presence of $0.11 / kg feed prices and labor and housing costs of $0.25 / d per sow.


Copyright Owner

Robert Frank Fitzgerald



Date Available


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File Size

145 pages