Genetic parameters for white blood cells, haemoglobin and growth in weaner pigs for genetic improvement of disease resilience

This study aimed to estimate genetic parameters for white blood cells and haemoglobin levels in weaner pigs and estimate their genetic correlations with multiple growth traits. Five weight measurements were collected on 2,025 Large White pigs. A proportion of these pigs (813 pigs) also had total and differential white blood cells and haemoglobin recorded at an average age of 36.4 days. Haematological variables included total white blood cells (WBC), and counts of lymphocytes (LLYM), neutrophils, monocytes, eosinophils (LEOS), basophils and haemoglobin (HbL). In addition, haemoglobin was recorded on farm with the HemoCue Hb 201+ analyser (HbF). Genetic parameters were estimated using an animal model and fitting common litter effect as an additional random effect for most traits. Heritabilities for total and differential blood cells varied from 0.11 ± 0.09 for LLYM to 0.46 ± 0.10 for LEOS. Both haemoglobin measures were heritable with estimates of 0.15 ± 0.08 for HbF and 0.30 ± 0.14 for HbL. Growth traits were moderately heritable including growth from weaning to five weeks of age which covered only a short time period of ten days. These heritability estimates demonstrated that white blood cells, haemoglobin and growth recorded in weaner pigs may be used to describe disease resilience. Genetic correlations between white blood cells or haemoglobin and growth traits were variable and a better understanding of factors affecting genetic correlations between white blood cells or haemoglobin and growth is needed.