Comparison of metabolic substrates in alligators and several birds of prey

Karen Sweazea, John P. McMurtry, Ruth M. Elsey, Patrick Redig, Eldon J. Braun

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

On average, avian blood glucose concentrations are 1.5-2 times those of mammals of similar mass and high concentrations of insulin are required to lower blood glucose. Whereas considerable data exist for granivorous species, few data are available for plasma metabolic substrate and glucoregulatory hormone concentrations for carnivorous birds and alligators. Birds and mammals with carnivorous diets have higher metabolic rates than animals consuming diets with less protein whereas alligators have low metabolic rates. Therefore, the present study was designed to compare substrate and glucoregulatory hormone concentrations in several birds of prey and a phylogenetically close relative of birds, the alligator. The hypothesis was that the combination of carnivorous diets and high metabolic rates favored the evolution of greater protein and fatty acid utilization leading to insulin resistance and high plasma glucose concentrations in carnivorous birds. In contrast, it was hypothesized that alligators would have low substrate utilization attributable to a low metabolic rate. Fasting plasma substrate and glucoregulatory hormone concentrations were compared for bald eagles (Haliaeetus leucocephalus), great horned owls (Bubo virginianus), red-tailed hawks (Buteo jamaicensis), and American alligators (Alligator mississippiensis). Avian species had high circulating β-hydroxybutyrate (10-21. mg/dl) compared to alligators (2.81 ± 0.16. mg/dl). In mammals high concentrations of this byproduct of fatty acid utilization are correlated with insulin resistance. Fasting glucose and insulin concentrations were positively correlated in eagles whereas no relationship was found between these variables for owls, hawks or alligators. Additionally, β-hydroxybutyrate concentrations were low in alligators. Similar to carnivorous mammals, ingestion of a high protein diet may have favored the utilization of fatty acids and protein for energy thereby promoting the development of insulin resistance and gluconeogenesis-induced high plasma glucose concentrations during periods of fasting in birds of prey.

Original languageEnglish (US)
Pages (from-to)253-260
Number of pages8
JournalZoology
Volume117
Issue number4
DOIs
StatePublished - 2014

Fingerprint

Raptors
Alligators and Crocodiles
alligators
birds of prey
Eagles
Birds
Mammals
insulin resistance
Bubo virginianus
mammals
Buteo jamaicensis
Hawks
Haliaeetus leucocephalus
fasting
Strigiformes
Hydroxybutyrates
Diet
Insulin Resistance
birds
Fasting

Keywords

  • Carnivore
  • Fatty acid
  • Glucose
  • Insulin
  • Metabolic rate

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Medicine(all)

Cite this

Comparison of metabolic substrates in alligators and several birds of prey. / Sweazea, Karen; McMurtry, John P.; Elsey, Ruth M.; Redig, Patrick; Braun, Eldon J.

In: Zoology, Vol. 117, No. 4, 2014, p. 253-260.

Research output: Contribution to journalArticle

Sweazea, K, McMurtry, JP, Elsey, RM, Redig, P & Braun, EJ 2014, 'Comparison of metabolic substrates in alligators and several birds of prey', Zoology, vol. 117, no. 4, pp. 253-260. https://doi.org/10.1016/j.zool.2014.04.002
Sweazea, Karen ; McMurtry, John P. ; Elsey, Ruth M. ; Redig, Patrick ; Braun, Eldon J. / Comparison of metabolic substrates in alligators and several birds of prey. In: Zoology. 2014 ; Vol. 117, No. 4. pp. 253-260.
@article{2c1c2f8726d24af88e2b8144ceafe2c1,
title = "Comparison of metabolic substrates in alligators and several birds of prey",
abstract = "On average, avian blood glucose concentrations are 1.5-2 times those of mammals of similar mass and high concentrations of insulin are required to lower blood glucose. Whereas considerable data exist for granivorous species, few data are available for plasma metabolic substrate and glucoregulatory hormone concentrations for carnivorous birds and alligators. Birds and mammals with carnivorous diets have higher metabolic rates than animals consuming diets with less protein whereas alligators have low metabolic rates. Therefore, the present study was designed to compare substrate and glucoregulatory hormone concentrations in several birds of prey and a phylogenetically close relative of birds, the alligator. The hypothesis was that the combination of carnivorous diets and high metabolic rates favored the evolution of greater protein and fatty acid utilization leading to insulin resistance and high plasma glucose concentrations in carnivorous birds. In contrast, it was hypothesized that alligators would have low substrate utilization attributable to a low metabolic rate. Fasting plasma substrate and glucoregulatory hormone concentrations were compared for bald eagles (Haliaeetus leucocephalus), great horned owls (Bubo virginianus), red-tailed hawks (Buteo jamaicensis), and American alligators (Alligator mississippiensis). Avian species had high circulating β-hydroxybutyrate (10-21. mg/dl) compared to alligators (2.81 ± 0.16. mg/dl). In mammals high concentrations of this byproduct of fatty acid utilization are correlated with insulin resistance. Fasting glucose and insulin concentrations were positively correlated in eagles whereas no relationship was found between these variables for owls, hawks or alligators. Additionally, β-hydroxybutyrate concentrations were low in alligators. Similar to carnivorous mammals, ingestion of a high protein diet may have favored the utilization of fatty acids and protein for energy thereby promoting the development of insulin resistance and gluconeogenesis-induced high plasma glucose concentrations during periods of fasting in birds of prey.",
keywords = "Carnivore, Fatty acid, Glucose, Insulin, Metabolic rate",
author = "Karen Sweazea and McMurtry, {John P.} and Elsey, {Ruth M.} and Patrick Redig and Braun, {Eldon J.}",
year = "2014",
doi = "10.1016/j.zool.2014.04.002",
language = "English (US)",
volume = "117",
pages = "253--260",
journal = "Zoology",
issn = "0944-2006",
publisher = "Urban und Fischer Verlag Jena",
number = "4",

}

TY - JOUR

T1 - Comparison of metabolic substrates in alligators and several birds of prey

AU - Sweazea, Karen

AU - McMurtry, John P.

AU - Elsey, Ruth M.

AU - Redig, Patrick

AU - Braun, Eldon J.

PY - 2014

Y1 - 2014

N2 - On average, avian blood glucose concentrations are 1.5-2 times those of mammals of similar mass and high concentrations of insulin are required to lower blood glucose. Whereas considerable data exist for granivorous species, few data are available for plasma metabolic substrate and glucoregulatory hormone concentrations for carnivorous birds and alligators. Birds and mammals with carnivorous diets have higher metabolic rates than animals consuming diets with less protein whereas alligators have low metabolic rates. Therefore, the present study was designed to compare substrate and glucoregulatory hormone concentrations in several birds of prey and a phylogenetically close relative of birds, the alligator. The hypothesis was that the combination of carnivorous diets and high metabolic rates favored the evolution of greater protein and fatty acid utilization leading to insulin resistance and high plasma glucose concentrations in carnivorous birds. In contrast, it was hypothesized that alligators would have low substrate utilization attributable to a low metabolic rate. Fasting plasma substrate and glucoregulatory hormone concentrations were compared for bald eagles (Haliaeetus leucocephalus), great horned owls (Bubo virginianus), red-tailed hawks (Buteo jamaicensis), and American alligators (Alligator mississippiensis). Avian species had high circulating β-hydroxybutyrate (10-21. mg/dl) compared to alligators (2.81 ± 0.16. mg/dl). In mammals high concentrations of this byproduct of fatty acid utilization are correlated with insulin resistance. Fasting glucose and insulin concentrations were positively correlated in eagles whereas no relationship was found between these variables for owls, hawks or alligators. Additionally, β-hydroxybutyrate concentrations were low in alligators. Similar to carnivorous mammals, ingestion of a high protein diet may have favored the utilization of fatty acids and protein for energy thereby promoting the development of insulin resistance and gluconeogenesis-induced high plasma glucose concentrations during periods of fasting in birds of prey.

AB - On average, avian blood glucose concentrations are 1.5-2 times those of mammals of similar mass and high concentrations of insulin are required to lower blood glucose. Whereas considerable data exist for granivorous species, few data are available for plasma metabolic substrate and glucoregulatory hormone concentrations for carnivorous birds and alligators. Birds and mammals with carnivorous diets have higher metabolic rates than animals consuming diets with less protein whereas alligators have low metabolic rates. Therefore, the present study was designed to compare substrate and glucoregulatory hormone concentrations in several birds of prey and a phylogenetically close relative of birds, the alligator. The hypothesis was that the combination of carnivorous diets and high metabolic rates favored the evolution of greater protein and fatty acid utilization leading to insulin resistance and high plasma glucose concentrations in carnivorous birds. In contrast, it was hypothesized that alligators would have low substrate utilization attributable to a low metabolic rate. Fasting plasma substrate and glucoregulatory hormone concentrations were compared for bald eagles (Haliaeetus leucocephalus), great horned owls (Bubo virginianus), red-tailed hawks (Buteo jamaicensis), and American alligators (Alligator mississippiensis). Avian species had high circulating β-hydroxybutyrate (10-21. mg/dl) compared to alligators (2.81 ± 0.16. mg/dl). In mammals high concentrations of this byproduct of fatty acid utilization are correlated with insulin resistance. Fasting glucose and insulin concentrations were positively correlated in eagles whereas no relationship was found between these variables for owls, hawks or alligators. Additionally, β-hydroxybutyrate concentrations were low in alligators. Similar to carnivorous mammals, ingestion of a high protein diet may have favored the utilization of fatty acids and protein for energy thereby promoting the development of insulin resistance and gluconeogenesis-induced high plasma glucose concentrations during periods of fasting in birds of prey.

KW - Carnivore

KW - Fatty acid

KW - Glucose

KW - Insulin

KW - Metabolic rate

UR - http://www.scopus.com/inward/record.url?scp=84905054281&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84905054281&partnerID=8YFLogxK

U2 - 10.1016/j.zool.2014.04.002

DO - 10.1016/j.zool.2014.04.002

M3 - Article

C2 - 25043840

AN - SCOPUS:84905054281

VL - 117

SP - 253

EP - 260

JO - Zoology

JF - Zoology

SN - 0944-2006

IS - 4

ER -