Influence of biological factors on hematological and serum biochemistry values in captive Adélie, Chinstrap, Gentoo, and Macaroni penguins in Pingtung, Taiwan

Hematology and serum biochemistry reference values are essential for health evaluation and disease diagnosis in penguins. However, there are currently no published physiological values for captive Adélie (Pygoscelis adeliae) and Chinstrap penguins (P. antarcticus), nor for wild or captive Macaroni penguins (Eudyptes chrysolophus). The present study is the first investigation regarding hematology and serum biochemistry reference values for captive Adélie, Gentoo (P. papua), Chinstrap, and Macaroni penguins in Asia. Fixed effect models for repeated measure were applied to determine the influence of penguin species, age, gender, and age‐gender interaction on each blood parameter. Hematology and serum biochemical data from 122 apparently healthy penguins (24 Adélie, 38 Chinstrap, 46 Gentoo, and 14 Macaroni) were collected between 2009 and 2014. The effects of penguin species were observed for most blood parameters, except total bilirubin, creatine kinase (CK), creatinine, and potassium ion (K+). Values of mean corpuscular volume, mean corpuscular hemoglobin (MCH), heterophil, ratio of heterophils to lymphocytes (H/L), alanine aminotransferase (ALT), and chloride ion (Cl‐) had significant positive correlation with age, while significant negative correlation with age was observed in total red blood cells (RBCs), lymphocytes, thrombocytes, alkaline phosphatase (ALP), CK, lactate dehydrogenase (LDH), and plasma iron. Compared to male penguins, females had lower mean corpuscular hemoglobin concentration (MCHC) and blood urea nitrogen (BUN) but higher calcium ion (Ca2+) values. As for age‐gender interaction, significant positive correlation was shown in MCHC and K+, and the reverse was true in H/L ratio.