Serum Biochemical Reference Values for Adult and Non-adult Chinese Alligators during the Deep and Late Hibernation Periods

Abstract

Background: The Chinese alligator (Alligator sinensis) is a critically endangered species. Due to the rapid growth of the captive population, the susceptibility to disease during the recovery period after winter hibernation, especially in young alligators, have detrimentally affected Chinese alligator populations. Serum biochemistry, which relates to metabolism, nutritional status and disease, is enormously helpful in evaluating physical conditions in reptile. Many studies have reported the serum biochemical reference values of various reptilian species, including several crocodilians. However, reference values for Chinese alligators have not yet been reported. For captive Chinese alligators, hibernation is a crucial period because winter management has a direct influence on the survival rate of juveniles and the reproduction rate of adults. The main object of the present study refore was to measure the serum biochemical values of captive Chinese alligators during hibernation.Materials, Methods & Results: As such, this study investigates the serum biochemistry as a factor of age and hibernation stage. During the deep and late hibernation periods blood samples were drawn from 30 healthy captive Chinese alligators (adults, sub-adults, and juveniles) at the Anhui Research Center of Chinese Alligator Reproduction (ARCCAR). Serum biochemical measurements were performed using an automated biochemical analyzer and compared based on the age group and hibernation stage via two-way ANOVA. During late hibernation, serum lactate dehydrogenase, alkaline phosphatase, and aspartate aminotransferase activity increased in all age groups in comparison to that in deep hibernation, while the concentration of calcium decreased. Meanwhile, the concentration of serum phosphorus, uric acid, total protein, and globulin in sub-adults and juveniles considerably increased in comparison to that in deep hibernation, while cholesterol and albumin declined. However, in adults only slight changes were noted. Based on comprehensive statistical analysis, our results indicate that sub-adults and juveniles are at risk of developing renal disease during artificial hibernation.Discussion: Chinese alligators, especially sub-adults and juveniles, are particularly vulnerable to disease when they wake from hibernation. They often display symptoms such as depression, anorexia, lethargy, sluggish movement, slow, incremental weight gain, progressive muscle wasting, and even death. The high rate of morbidity in non-adult Chinese alligators may be associated with the high density of UA and other changes in multiple biochemical markers that occur during late hibernation. These altered serum biochemical profiles may indicate kidney damage. One of the most common diseases among reptiles is nephropathy, the symptoms of which are non-specific and tend to agree with those observed post-hibernation. In summary, this study has reported the serum biochemical values of Chinese alligators of varying ages in the deep and late hibernation phases. Based on statistical analyses, interesting differences between the serum biochemical values of adults and non-adults during the deep and late hibernation have been found. The observed changes suggest that, under an artificial hibernation environment, the kidneys of sub-adults and juveniles may become impaired. We believe that the data reported in this study will provide clinical guidance to facilitate more appropriate artificial wintering conditions for Chinese alligators, and assist the breeding and management of these reptiles, as well as disease prevention, during hibernation and recovery.