RESUMO
This study aimed to evaluate the influence of age and sex on the blood biochemical constituents of broiler breeders during the egg production stage. The analysis was performed in an industrial broiler breeder farm, and blood samples were collected from males and females at five different ages. Biochemical elements analysed in each serum sample were total proteins, albumin, globulins, uric acid, total cholesterol and triglycerides, alanine aminotransferase (ALT) and aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT), creatine kinase (CK), alkaline phosphatase (PAL), calcium and phosphorus, beside the glycaemic status. At most ages, females had higher values of total proteins, albumin, globulins, triglycerides, cholesterol, glucose, calcium, phosphorus, Ca/P (calcium and phosphorus) ratio and gamma-glutamyltransferase (GGT). The values of uric acid, aspartate aminotransferase (AST), creatine kinase (CK) and alkaline phosphatase (PAL) were higher in males. The lowest protein values were found at 28 and 60 weeks old. The mean albumin values were significantly higher at 44 and 52 weeks old in males and females. A trend of increasing globulin values with increasing age up to 52 weeks old was observed. Although calcium and phosphorus did not vary according to age, the Ca/P ratio was lowest at 36 weeks old. Comparing the means of both sexes, the AST and GGT values were significantly higher in 60-week-old birds. The highest serum levels of CK occurred at 28 and 52 weeks old. The physiological levels of serum biomarkers presented in this work are important for evaluating productivity performance, welfare and disease indication in breeding flocks.