PSIII-24 Blood serum biochemistry analysis of White Leghorn chickens selected for divergent blood antibody titer response to sheep red blood cells.

Abstract For fifty generations, White Leghorn chickens have been selected for divergent responses to a low-dose injection of sheep red blood cells (SRBCs) generating the high (HAS) or low (LAS) antibody response lines. This project aimed to determine whether selection for systemic antibody concentrations might result in correlated responses in blood serum biochemistry profiles. Males and females from HAS and LAS lines were raised under standard conditions. Blood samples were collected at 4, 8, 12, 16, and 66 weeks of age (n=8-12 chickens/group/sex/age) and were processed to collect serum. Serum samples were loaded in the Avian rotors and analyzed using MicroChem II (MicroVet Diagnostics) equipment [total protein (TP), albumin, globulin, albumin:globulin (A:G) ratio, aspartate transferase (AST), total bile acid (TBA), creatinine kinase (CK), uric acid (UA), glucose, calcium, phosphorus, potassium, and sodium]. Data were analyzed by two-way ANOVA followed by Sídák posthoc test, P< 0.05 was considered significant. Our results showed that HAS had higher globulin, TP (12 weeks), potassium, and lower A:G ratio serum concentrations than LAS (P< 0.05). Globulin is a group of blood pro-inflammatory proteins, which includes alpha-globulins, beta-globulins, and gamma-globulins or immunoglobulins (antibodies). TP is the sum of albumin and globulin concentrations, and A:G ratio is a marker for inflammatory diseases (lower values are related to increased globulin levels). The TP, globulin, and A:G ratios are consistent with the selection of HAS for higher antibody concentration. High levels of serum potassium are usually caused by kidney diseases or high-potassium diets, which were not reported in our study, suggesting that the high potassium levels were a result of the divergent selection for SRBC. Additionally, at 66 weeks of age higher concentration of CK was observed in HAS than in LAS (P< 0.05). CK is a muscle injury marker, animals with higher blood concentrations of antibodies are known to develop deposits of these proteins in diverse tissues that cause tissue damage. At 66 weeks females from both groups had higher TBA, calcium, phosphorus, and lower uric acid than their male counterparts (P< 0.05). TBA is a liver function marker, when higher than reference levels indicate liver damage, however, the levels in the present study were within the reference indicating increased liver function, consistent with the production of proteins and lipids necessary for egg production and leading to decreased UA production. Calcium and phosphorus are required for eggshell synthesis. These findings are consistent with the laying hens’ biochemistry profile. In conclusion, our results showed that these divergent lines had different blood biochemistry profiles showing the necessity to further evaluate the correlated responses to selection for antibody production through generations.