RESUMO
BACKGROUND: The developmental profile of chicken carbonic anhydrase-III (CA-III) blood levels has not been previously determined or reported. We isolated CA-III from chicken muscle and investigated age-related changes in the levels of CA-III in blood. METHODS: CA-III was purified from chicken muscle. The levels of CA-III in plasma and erythrocytes from 278 female chickens (aged 1-93 weeks) and 68 male chickens (aged 3-59 weeks) were determined by ELISA. RESULTS: The mean level of CA-III in female chicken erythrocytes (1 week old) was 4.6 µg/g of Hb, and the CA-III level did not change until 16 weeks of age. The level then increased until 63 weeks of age (11.8 µg/g of Hb), decreased to 4.7 µg/g of Hb at 73 weeks of age, and increased again until 93 weeks of age (8.6 µg/g of Hb). The mean level of CA-III in erythrocytes from male chickens (3 weeks old) was 2.4 µg/g of Hb, and this level remained steady until 59 weeks of age. The mean plasma level of CA-III in 1-week-old female chickens was 60 ng/mL, and this level was increased at 3 weeks of age (141 ng/mL) and then remained steady until 80 weeks of age (122 ng/mL). The mean plasma level of CA-III in 3-week-old male chickens was 58 ng/mL, and this level remained steady until 59 weeks of age. CONCLUSION: We observed both developmental changes and sex differences in CA-III concentrations in White Leghorn (WL) chicken erythrocytes and plasma. Simple linear regression analysis showed a significant association between the erythrocyte CA-III level and egg-laying rate in WL-chickens 16-63 weeks of age (p < 0.01).
