The Influence of Reproductive Experience on Milk Energy Output and Lactation Performance in the Grey Seal (Halichoerus grypus)
Date
2011-05
Authors
Lang, Shelley L. C.
Iverson, Sara J.
Bowen, W. Don
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Although evidence from domestic and laboratory species suggests that reproductive experience
plays a critical role in the development of aspects of lactation performance, whether reproductive
experience may have a significant influence on milk energy transfer to neonates in wild populations
has not been directly investigated. We compared maternal energy expenditures and pup growth and
energy deposition over the course of lactation between primiparous and fully-grown, multiparous grey
seal (Halichoerus grypus) females to test whether reproductive experience has a significant
influence on lactation performance. Although there was no difference between primiparous females in
milk composition and, thus, milk energy content at either early or peak lactation primiparous
females had a significantly lower daily milk energy output than multiparous females indicating a
reduced physiological capacity for milk secretion. Primiparous females appeared to effectively
compensate for lower rates of milk production through an increased nursing effort and, thus,
achieved the same relative rate of milk energy transfer to pups as multiparous females. There was no
difference between primiparous and multiparous females in the proportion of initial body energy
stores mobilised to support the costs of lactation. Although primiparous females allocated a greater
proportion of energy stores to maternal maintenance versus milk production than multiparous females,
the difference was not sufficient to result in significant differences in the efficiency of energy
transfer to pups. Thus, despite a lower physiological capacity for milk production, primiparous
females weaned pups of the same relative size and condition as multiparous females without expending
proportionally more energy. Although reproductive experience does not significantly affect the
overall lactation performance of grey seals, our results suggest that increases in mammary gland
capacity with reproductive experience may play a significant role in the age-related increases in
neonatal growth rates and weaning masses observed in other free-ranging mammals.
Description
Keywords
Citation
Lang, Shelley L. C., Sara J. Iverson, and W. Don Bowen. 2011. "The Influence of Reproductive Experience on Milk Energy Output and Lactation Performance in the
Grey Seal (Halichoerus grypus)." Plos One 6(5): 19487-e19487.