Evaluating Differences in Stress Levels in Lean Growth Versus Control Landrace Pigs

Purdue University 2000 Swine Research Report. In livestock, aggression may lead to difficulties in handling and decreased animal wellbeing. Pigs selected for lean growth are thought by producers to be more difficult to handle. Previous studies have shown that leaner terminal cross pigs exhibit higher levels of aggression than maternal lines of pigs. Human studies suggest that there is a relationship between peripheral whole blood serotonin (WBS) and violence in men. In this study, a possible relationship between leanness and WBS was investigated in weanling pigs. One problem with comparing pigs from differing type of crosses is they have a large number of genetic differences that may result in spurious correlations. A better experimental design is to compare pigs that come from a common genetic background that have been selected for increased leanness. Daryl Kuhlers of Auburn University has selected a line of Landrace for increased loin eye area. After six generations, the select line differs from the control line by 1.6 square inches. This study examines the behavioral and physiological differences between these two genetic lines of Landrace pigs.