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

Biology Department, Dalhousie University, Halifax, Nova Scotia, Canada.
Journal of Comparative Physiology B (Impact Factor: 2.62). 10/1999; 169(6):377-90. DOI: 10.1007/s003600050234
Source: PubMed

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, 3H2O), 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 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).

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Available from: Jo-Ann E Mellish, Sep 28, 2015
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    • "Males may also be freer to enter the water and occasionally feed during breeding, as opposed to the moulting period when both sexes fast for a similar amount of time. It has been suggested that the energetic costs associated with the immediate migration after breeding followed by reduced food intake during the moult must be met from energy stored prior to the breeding season or from what have been acquired during the migration between breeding and moulting [63]. The relatively poor body condition after the moult (or less relative lipid content) observed for both sexes suggests that the post moult migration marks the beginning of the build up of energy reserves to prepare them for breeding and consequently the moult. "
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    ABSTRACT: Many pinniped species perform a specific dive type, referred to as a 'drift dive', where they drift passively through the water column. This dive type has been suggested to function as a resting/sleeping or food processing dive, and can be used as an indication of feeding success by calculating the daily change in vertical drift rates over time, which reflects the relative fluctuations in buoyancy of the animal as the proportion of lipids in the body change. Northwest Atlantic hooded seals perform drift dives at regular intervals throughout their annual migration across the Northwest Atlantic Ocean. We found that the daily change in drift rate varied with geographic location and the time of year and that this differed between sexes. Positive changes in buoyancy (reflecting increased lipid stores) were evident throughout their migration range and although overlapping somewhat, they were not statistically associated with high use areas as indicated by First Passage Time (FPT). Differences in the seasonal fluctuations of buoyancy between males and females suggest that they experience a difference in patterns of energy gain and loss during winter and spring, associated with breeding. The fluctuations in buoyancy around the moulting period were similar between sexes.
    PLoS ONE 07/2014; 9(7). DOI:10.1371/journal.pone.0103072 · 3.23 Impact Factor
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    • "For example, lactation times vary from 4 days in the hooded seal (Cystophora cristata (Erxleben, 1777)) to 6–20 weeks in the Mediterranean monk seal (Monachus monachus (Hermann, 1779)), uncovering a phenomenon that growth rates are highest in species with the shortest lactation period (Sergeant et al. 1978; Bowen et al. 1985; Kovacs 1990; Aguilar et al. 2007). Earlier studies were mainly reports on large-bodied phocids (>150 kg; Mellish et al. 1999a, 1999b; Crocker et al. 2001; Riek 2008); however, to date, scientists have begun to pay attention to the lactation dynamics of small-bodied seals (<150 kg), as relatively little is known about the variation in the patterns of energy transfer and allocation during lactation in these smaller phocid species and the consequences this variation has on pup mass gain (Lydersen et al. 1992; Lang et al. 2005). This lack of data limits our understanding of the evolution of diverse lactation strategies in pinnipeds. "
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    ABSTRACT: As lactation is commonly very brief in phocid seals, the transfer of sufficient energy between mother and offspring is critical for their reproductive success. In this study, we investigated variation in the pattern of energy transfer and allocation during lactation in the spotted seal (Phoca largha Pallas, 1811). Temporal changes in milk composition, milk consumption, and pup mass gain were analyzed from birth to weaning in a spotted seal pup that was hand-reared on a donor-female’s milk. In addition, growth rates were measured in six pups raised in captivity but nursed naturally. We found that milk fat content increased and water content decreased during lactation. We calculated that spotted seal pup ingest a mean (±SD) daily energy of 39.5 ± 8.6 MJ/day, which corresponded to a daily mass gain of 0.9 kg/day. We found that the growth rates of the hand-reared pup and the six naturally reared pups did not differ, and overall, the mean (±SD) daily growth rate of spotted seal pups was 1.1 ± 0.2 kg/day before weaning and 0.6 ± 0.2 kg/day from birth to molt. Our study provides the first data on lactation patterns in this species.
    Canadian Journal of Zoology 05/2014; 92(5). DOI:10.1139/cjz-2013-0295 · 1.30 Impact Factor
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    • "However, a comparison to hooded seals (Phocidae: Cystophora cristata) is instructive. Considering metrics other than MF, newborn hooded seals pups are among the most precocial of mammals: they are large (10%–12% of maternal BM compared to the phocid average of ~9%; Oftedal et al. 1993, Mellish et al. 1999, Schulz and Bowen 2005), close to chemically mature, as indicated by the water content of fat-free mass (Moulton 1923, Widdowson 1950, Oftedal et al. 1993, Mitchell 2007), contain significant amounts of body fat (Oftedal et al. 1993), and have already molted their lanugo in utero (Oftedal et al. 1991). The advanced state of maturity at birth in the hooded seal is likely an adaptation to pupping on unstable pack ice and has the selective advantage of minimizing the period of maternal dependence to less than four days (Bowen et al. 1985, Oftedal et al. 1993). "
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    ABSTRACT: Little is known about the ontogeny of brain size in pinnipeds despite potential functional implications of brain substrate (glucose, oxygen) requirements for diving, fasting, growth, and lactation strategies. We measured brain mass (brM) and cranial capacity (CC) in newborn and adult Weddell seals. Neonatal Weddell seals had brM that represented ~70% of adult brM. Weddell seals have the largest neonatal brain, proportional to adult brain, reported for any mammal to date, which is remarkable considering the relatively small size of Weddell seal pups at birth (6%–7% of maternal body mass) compared to neonates of other highly precocial mammals. Provision of sufficient glucose to maintain the large, well-developed brain of the neonatal Weddell seal has a nontrivial metabolic cost to both pup and mother. We therefore hypothesize that this phenomenon must have functional significance, such as allowing pups to acquire complex under-ice navigation skills during the period of maternal attendance.
    Marine Mammal Science 01/2014; 30(1). DOI:10.1111/mms.12033 · 1.94 Impact Factor
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