Ovarian acyclicity in zoo African elephants (Loxodonta africana) is associated with high body condition scores and elevated serum insulin and leptin
Kari A. Morfeld A B and Janine L. Brown A
+ Author Affiliations
- Author Affiliations
A Center for Species Survival, Smithsonian Conservation Biology Institute, National Zoological Park, 1500 Remount Road, Front Royal, VA 22630, USA.
B Corresponding author. Email: morfeldk@si.edu
Reproduction, Fertility and Development 28(5) 640-647 https://doi.org/10.1071/RD14140
Submitted: 29 April 2014 Accepted: 3 September 2014 Published: 7 November 2014
Abstract
The purpose of the present study was to determine whether excessive body fat and altered metabolic hormone concentrations in the circulation were associated with ovarian acyclicity in the world’s largest land mammal, the African elephant. We compared body condition, glucose, insulin and leptin concentrations and the glucose-to-insulin ratio (G : I) between cycling (n = 23; normal 14–16 week cycles based on serum progestagens for at least 2 years) and non-cycling (n = 23; consistent baseline progestagen concentrations for at least 2 years) females. A validated body condition score (BCS) index (five-point scale; 1 = thinnest, 5 = fattest) was used to assess the degree of fatness of the study elephants. The mean BCS of non-cycling elephants was higher than that of their cycling counterparts. There were differences in concentrations of serum metabolic biomarkers, with non-cycling elephants in the BCS 5 category having higher leptin and insulin concentrations and a lower G : I ratio than cycling BCS 5 females. Using ‘non-cycling’ as the outcome variable in regression models, high BCS was a strong predictor of a non-cycling status. This study provides the first evidence that ovarian acyclicity in zoo African elephants is associated with body condition indicative of obesity, as well as elevated, perturbed biomarkers of metabolic status.
Additional keywords: infertility, metabolic hormones, obesity, reproduction.
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