Keratin Glucocorticoid Analysis by Enzyme Immunoassay in Mammals, Birds and Reptiles

Berkvens, Charlene N.
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University of Guelph

This thesis investigates the use of an enzyme immunoassay to measure keratin glucocorticoid concentrations in mammalian hair, bird feathers and reptilian shed skins. Keratin glucocorticoid concentrations were compared to fecal glucocorticoid concentrations produced during the period of keratin growth in the African Elephant (Loxodonta africana), the Western Lowland Gorilla (Gorilla gorilla gorilla), the Sumatran Orangutan (Pongo abelii), the Domestic Chicken (Gallus gallus domesticus), the Eastern Loggerhead Shrike (Lanius ludovicianus migrans), the African House Snake (Lamprophis fuliginosus) and the Eastern Massasauga Rattlesnake (Sistrurus catenatus catenatus). Complete biochemical validation was performed for the feather and shed skin corticosterone and fecal corticosterone enzyme immunoassays in the Domestic Chicken and the African House Snake. Biological validation was performed in the Domestic Chicken. Biological and physiological validation were attempted in the African House Snake. African Elephant, Western Lowland Gorilla and Sumatran Orangutan hair cortisol concentrations ranged from 2.10 - 312.70 ng/g. African Elephant hair corticosterone concentrations ranged from 2.68 - 20.70 ng/g. Domestic Chicken and Eastern Loggerhead Shrike feather corticosterone concentrations ranged from 1.31 - 8.09 pg/mm and from 1.09 - 6.59 pg/mm, respectively. African House Snake and Massasauga Rattlesnake shed skin corticosterone concentrations ranged from 4.42 - 124.35 ng/g and 3.82 - 22.85 ng/g, respectively. In the majority of cases, a statistically significant association was not found between summary statistical measures of fecal and keratin glucocorticoid concentrations. A statistically significant positive association was detected between hair cortisol and the coefficient of variation of fecal corticosterone in the African Elephants. A statistically significant negative association was detected between feather corticosterone and the 75th percentile and coefficient of variation of fecal corticosterone in the Eastern Loggerhead Shrikes. A statistically significant positive association was also detected between shed skin corticosterone and the mean fecal corticosterone from 3 weeks before to 1 week after the previous ecdysis in the African House Snake. Feather corticosterone concentrations were significantly higher in feathers from Domestic Chickens that were socially housed with roosters than in feathers from chickens housed individually in laying cages. A statistically significant difference was not detected between the shed skin corticosterone concentrations of the minimally handled control and the weekly handled experimental African House Snakes. Adrenocorticotropic hormone stimulation did not result in the physiological validation anticipated for shed skin corticosterone concentrations in the African House Snake.

Keratin, Glucocorticoid, Cortisol, Corticosterone, Hair, Feather, Shed Skin