Associations of weight gain and food intake with leukocyte sub-sets in Large White pigs

Associations between productivity and a range of immune traits were tested by multiple regression analysis on 128 Large White pigs (62 male, 66 female). Daily weight gain, daily feed intake, and efficiency (i.e. weight gain/feed intake), assessed from 14 to 24 weeks of age, were the productivity traits. Total and differential white blood cell count and leukocyte sub-sets positive for CD4, CD8, CD11R1, gamma delta T cells, B cell, and monocyte markers, all measured at 18 and 24 weeks, were the immune traits. At 24 weeks of age, higher percentages of monocytes were associated with a decrease in daily weight gain. Higher percentages of B cells were associated with a decrease in daily feed intake. Higher percentages of CD11R1 positive cells were associated with a decrease in daily weight gain and a decrease in efficiency. Relationships at the age of 18 weeks were similar, but slightly less significant. Associations between the numbers of monocytes, MIL-4 positive cells and B cells and certain performance traits were also observed at the age of 24 weeks. Overall, these results indicate an association between productivity and certain immune traits. We suggest that the observed associations between these immune traits and performance could be due to the impact of sub-clinical infections.