The Effect of Maternal Size and Milk Energy Output on Pup Growth in Grey Seals (Halichoerus grypus)

Iverson, Sara J.; Bowen, W. D.; Boness, Daryl J.; Oftedal, Olav T.

doi:10.1086/physzool.66.1.30158287

Cited by 190 publications

(188 citation statements)

References 37 publications

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“…TBW was estimated from the dilution space using a previously derived equation for pinnipeds (Bowen and Iverson, 1998). Fat mass was determined from TBW using the equation: Iverson et al, 1993), where M F is the fat mass of the seal (in kg) and M T is the total body mass (kg). Daily energy expenditure (DEE) was estimated from mass and body composition changes.…”

Section: Body Composition and Energy Expenditurementioning

confidence: 99%

Hormone and metabolite changes associated with extended breeding fasts in male northern elephant seals (Mirounga angustirostris)

Crocker

Ortiz

Houser

et al. 2012

Comparative Biochemistry and Physiology Part A: Molecular &

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We measured metabolic hormones and several key metabolites in breeding adult male northern elephant seals to examine the regulation of fuel metabolism during extended natural fasts of over 3 months associated with high levels of energy expenditure. Males were sampled twice, early and late in the fast, losing an average of 23% of body mass and 47% of adipose stores between measurements. Males exhibited metabolic homeostasis over the breeding fast with no changes in glucose, non-esterified fatty acids, or blood urea nitrogen. Ketoacids increased over the fast but were very low when compared to other fasting species. Changes within individuals in total triiodothyronine (tT 3 ) were positively related to daily energy expenditure (DEE) and protein catabolism. Differences in levels of thyroid hormones relative to that observed in weaned pups and females suggest a greater deiodination of T 4 to support the high DEE of breeding males. Relative levels of leptin and ghrelin were consistent with the suppression of appetite but a significant reduction in growth hormone across the fast was contrary to expectation in fasting mammals. The lack of the increase in cortisol during fasting found in conspecific weaned pups and lactating females may contribute to the ability of breeding males to spare protein despite high levels of energy expenditure. Together these findings reveal significant differences with conspecifics under varying nutrient demands, suggesting metabolic adaptation to extended high energy fasts.

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Section: Body Composition and Energy Expenditurementioning

confidence: 99%

Hormone and metabolite changes associated with extended breeding fasts in male northern elephant seals (Mirounga angustirostris)

Crocker

Ortiz

Houser

et al. 2012

Comparative Biochemistry and Physiology Part A: Molecular &

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“…hooded seals (179 kg), grey seals (207 kg), and northern elephant seals (509 kg). The total milk outputs (kg) in these species have been measured as 30-31, 48 and 138 (Iverson et al 1993;Oftedal et al 1993b;Lydersen et al 1995Lydersen et al , 1997, representing about 17, 23 and 27 % maternal M respectively. The corresponding fat outputs are 18, 27 and 59 kg, while protein outputs are 1·6, 4·7 and 10·6 kg.…”

Section: The True Seals (Carnivora: Phocidae)mentioning

confidence: 99%

Use of maternal reserves as a lactation strategy in large mammals

2000

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The substrate demands of lactation must be met by increased dietary intake or by mobilization of nutrients from tissues. The capacity of animals to rely on stored nutrients depends to a large extent on body size; large animals have greater stores, relative to the demands of lactation, than do small animals. The substrate demands of lactation depend on the composition and amount of milk produced. Animals that fast or feed little during lactation are expected to produce milks low in sugar but high in fat, in order to minimize needs for gluconeogenesis while sustaining energy transfers to the young. The patterns of nutrient transfer are reviewed for four taxonomic groups that fast during part of or throughout lactation: sea lions and fur seals (Carnivora: Otariidae), bears (Carnivora: Ursidae), true seals (Carnivora: Phocidae) and baleen whales (Cetacea: Mysticeti). All these groups produce low-sugar high-fat milks, although the length of lactation, rate of milk production and growth of the young are variable. Milk protein concentrations also tend to be low, if considered in relation to milk energy content. Maternal reserves are heavily exploited for milk production in these taxa. The amounts of lipid transferred to the young represent about one-fifth to one-third of maternal lipid stores; the relative amount of the gross energy of the body transferred in the milk is similar. Some seals and bears also transfer up to 16-18 % of the maternal body protein via milk. Reliance on maternal reserves has allowed some large mammals to give birth and lactate at sites and times far removed from food resources. Lactation involves the mobilization and export of substantial quantities of nutrients in milk, placing large nutrient demands on the mother. If she is unable to meet these added demands by dietary intake, she must reduce milk output, mobilize nutrients from maternal tissues or employ some combination thereof. However, reduction in milk output may compromise survival of the young. In nature, lactation is often timed to periods of food abundance so that the mother can match dietary intake to lactational needs, and does not have to choose between her own future and that of her offspring.An alternative approach is to disengage lactation from maternal food intake by storing nutrients in tissues during periods of abundance and then mobilizing these nutrients into milk at a later date. Such an approach is only possible if the types and amounts of nutrients stored in tissues are sufficient to cover the demands of lactation. The sufficiency of nutrient storage is largely governed by the allometry of energy expenditure (Oftedal, 1993): since small animals expend energy at a much higher rate (relative to body mass) than large animals, small animals are physically unable to store sufficient energy to cover expenditures for any length of time.A simple calculation for 4 g shrews illustrates this point. If a shrew deposits body fat equivalent to 250 mg/g body mass (M), the energy content of the fat stores will be about 39 kJ, while lea...

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“…Grey seals are characterised by having a short (from 16 to 21 days) and intense lactation period (Pomeroy et al, 1996). During that time, females produce milk extremely rich in lipids (up to 60%), while fasting (Iverson et al, 1993;Pomeroy et al, 1996). Because females do not eat throughout the lactation, milk lipids derive only from their own body stores.…”

Section: Introductionmentioning

confidence: 99%

Effects of polychlorobiphenyls, polybromodiphenylethers, organochlorine pesticides and their metabolites on vitamin A status in lactating grey seals

Berghe

Weijs

Habran

et al. 2013

Environmental Research

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a b s t r a c tPolychlorobiphenyls (PCBs), polybromodiphenylethers (PBDEs) and organochlorine pesticides (OCPs), such as dichlorodiphenyltrichloroethane (DDT) and hexachlorobenzene (HCB), are considered as endocrine disruptors in laboratory and wild animals. This study investigated whether these compounds and their hydroxylated metabolites (HO-PCBs and HO-PBDEs) may affect the homoeostasis of vitamin A, a dietary hormone, in the blubber and serum of twenty lactating grey seals sampled at early and late lactation on the Isle of May, Scotland. The effect of naturally produced compounds such as the methoxylated (MeO)-PBDEs was also examined. Vitamin A levels in inner blubber (37 7 9 mg/g wet weight (ww) and 92 7 32 mg/g ww at early and late lactation, respectively) and serum (408 7 143 and 390 7 98 ng/ml at early and late lactation, respectively) appeared to be positively related to SPCBs, SPBDEs and several individual PCB and PBDE congeners in inner blubber and serum. These findings may suggest enhanced mobilisation of hepatic retinoid stores and redistribution in the blubber, a storage site for vitamin A in marine mammals. We have also reported that serum concentrations of SHO-PCBs and 4-OH-CB107 tended to increase with circulating vitamin A levels. Although the direction of the relationships may sometimes differ from those reported in the literature, our results are in agreement with previous findings highlighting a disruption of vitamin A homoeostasis in the blubber and bloodstream following exposure to environmental pollutants. The fact that vitamin A and PCBs appeared to share common mechanisms of mobilisation and transfer during lactation in grey seals (Debier et al., 2004;Vanden Berghe et al., 2010) may also play a role in the different relationships observed between vitamin A and lipophilic pollutants.

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The Effect of Maternal Size and Milk Energy Output on Pup Growth in Grey Seals (Halichoerus grypus)

Cited by 190 publications

References 37 publications

Hormone and metabolite changes associated with extended breeding fasts in male northern elephant seals (Mirounga angustirostris)

Hormone and metabolite changes associated with extended breeding fasts in male northern elephant seals (Mirounga angustirostris)

Use of maternal reserves as a lactation strategy in large mammals

Effects of polychlorobiphenyls, polybromodiphenylethers, organochlorine pesticides and their metabolites on vitamin A status in lactating grey seals

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