Journal of Comparative Physiology B

, Volume 169, Issue 6, pp 377–390

Fat transfer and energetics during lactation in the hooded seal: the roles of tissue lipoprotein lipase in milk fat secretion and pup blubber deposition

Authors

  • J. E. Mellish
    • Biology Department, Dalhousie University, Halifax, Nova Scotia, B3H 4J1, Canada e-mail: jmellish@is2.dal.ca Tel.: +1-902-494-2566; Fax: +1-902-494-3736
  • S. J. Iverson
    • Biology Department, Dalhousie University, Halifax, Nova Scotia, B3H 4J1, Canada e-mail: jmellish@is2.dal.ca Tel.: +1-902-494-2566; Fax: +1-902-494-3736
  • W. D. Bowen
    • Marine Fish Division, Bedford Institute of Oceanography, Department of Fisheries and Oceans, Dartmouth, Nova Scotia, B2Y 4A2, Canada
  • M. O. Hammill
    • Institut Maurice Lamontagne, CP 1000, Mont-Joli, Quebec, G5H 3Z4, Canada
ORIGINAL PAPER

DOI: 10.1007/s003600050234

Cite this article as:
Mellish, J., Iverson, S., Bowen, W. et al. J Comp Physiol B (1999) 169: 377. doi:10.1007/s003600050234

Abstract

Hooded seals (Cystophora cristata) lactate for 3.6 days during which females simultaneously fast and transfer large amounts of energy to their pups through fat-rich milk. Pups grow rapidly, principally due to blubber deposition. Lipoprotein lipase (LPL), the primary enzyme responsible for tissue uptake of triglyceride fatty acids, may strongly influence both maternal milk fat secretion and pup blubber deposition. We measured the energetic costs of lactation (using hydrogen isotope dilution, 3H20), milk composition, prolactin, and LPL activity (post-heparin plasma LPL [PH LPL], blubber, mammary gland and milk; U) in six females. PH LPL and blubber LPL were measured in their pups. Females depleted 216.3 MJ · day−1 of body energy and fat accounted for 59% of maternal mass loss and 90% of postpartum body energy loss, but maternal body composition changed little. Maternal blubber LPL was negligible (0.0–0.2 U), while mammary LPL was elevated (1.8–2.5 U) and was paralleled by changes in prolactin. Estimated total mammary LPL activity was high (up to 20,000 U · animal−1) effectively favoring the mammary gland for lipid uptake. Levels of total blubber LPL in pups increased seven-fold over lactation. Pups with higher PH LPL at birth had greater relative growth rates (P = 0.025). Pups with greater blubber stores and total blubber LPL activity had elevated rates of fat deposition (P = 0.035).

Key words Lactation Lipoprotein lipase (LPL) Prolactin Milk composition Hooded seal Cystophora cristata

Copyright information

© Springer-Verlag Berlin Heidelberg 1999