Related Experiment Video
Updated: Aug 18, 2026

Intranasal Immunization and Milk Collection in Studies of Maternal Immunization in New Zealand White Rabbits (Oryctolagus cuniculus)
Published on: July 31, 2021
Lactation during hibernation in wild black bears: effects on plasma amino acids and nitrogen metabolites
P A Wright1, M E Obbard, B J Battersby
1Department of Zoology, University of Guelph, Guelph, Ontario N1G 2W1, Canada. patwrigh@guelph.ca
Abstract:
This study examined the seasonal and reproductive influences on individual plasma amino acid concentrations and nitrogen metabolites in a black bear population (Ontario, Canada). During hibernation, 11 of 23 plasma amino acids were significantly higher (13%-108%) in lactating than in nonlactating females, without an alteration in plasma total protein or total essential or nonessential amino acid levels. The greatest changes were observed in glutamine, arginine, and glycine levels. Plasma urea, urea/creatinine, and ammonia levels were significantly lower in hibernating compared with active female bears, but lactation had no effect on these parameters. Taken together these results show that lactation during hibernation is an additional metabolic challenge that results in increased mobilization of individual plasma amino acids and no accumulation of nitrogen end products, underlining the remarkable efficiency of amino acid and urea recycling in denning female black bears.
Related Concept Videos
Parental Care
Metabolic States of the Body: The Absorptive State
Metabolic States of the Body: The Postabsorptive State
Initially, glycogen stored in the liver is broken down to release glucose into the bloodstream, while glycogen in the muscles is broken down to supply glucose for energy directly within the muscle cells. As glycogen stores diminish,...
Metabolic States of the Body: Fasting and Starvation

