Blood metabolites as indicators of nutrient utilization in fasting, lactating phocid seals: does depletion of nutrient reserves terminate lactation?

Mellish, JE; Iverson, Sara J.

doi:10.1139/z00-208

Cited by 22 publications

(16 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Protein is also an important source of energy for both large and small hibernating mammals (Cherel et al, 1995;Tinker et al, 1998), and an adequate balance of fat and protein use is apparently part of a common repertory in several spontaneous fasters, the control of which is poorly known (Robin et al, 1998;Mellish and Iverson, 2001). The degree of protein catabolism correlates with the size of the initial fat reserves in the species examined; the young tegus, with their small size and limited capacity to store fat, may derive more energy from protein during the fasting period, and particularly on arousal, than at later stages of development.…”

Section: Discussionmentioning

confidence: 99%

Seasonal metabolic depression, substrate utilisation and changes in scaling patterns during the first year cycle of tegu lizards (Tupinambis merianae)

Souza

Carvalho

Abe

et al. 2004

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARYThe tegus increase in body mass after hatching until early autumn, when the energy intake becomes gradually reduced. Resting rates of oxygen consumption in winter drop to 20% of the values in the active season(V̇O2=0.0636 ml g-1 h-1) and are nearly temperature insensitive over the range of 17-25°C (Q10=1.55). During dormancy, plasma glucose levels are 60% lower than those in active animals, while total protein, total lipids and β-hydroxybutyrate are elevated by 24%, 43% and 113%,respectively. In addition, a significant depletion of liver carbohydrate (50%)and of fat deposited in the visceral fat bodies (24%) and in the tail (25%)and a slight loss of skeletal muscle protein (14%) were measured halfway through the inactive period. Otherwise, glycogen content is increased 4-fold in the brain and 2.3-fold in the heart of dormant lizards, declining by the onset of arousal. During early arousal, the young tegus are still anorexic,although V̇O2 is significantly greater than winter rates. The fat deposits analysed are further reduced (62% and 45%, respectively) and there is a large decrease in tail muscle protein (50%) together with a significant increase in glycogen(2-3-fold) and an increase in plasma glucose (40%), which suggests a role for gluconeogenesis as a supplementary energy source in arousing animals. No change is detectable in citrate synthase activity, but β-hydroxyacyl CoA dehydrogenase activities are strongly affected by season, reaching a 3-fold and 5-fold increase in the liver tissue of winter and arousing animals,respectively, and becoming reduced by half in skeletal muscle and heart of winter animals compared with late fall or spring active individuals. From hatching to late autumn, the increase of the fat body mass relatively to body mass is disproportionate (b=1.44), and the mass exponent changes significantly to close to 1.0 during the fasting period. The concomitant shift in the V̇O2 mass exponent in early autumn (b=0.75) to values significantly greater than 1.0 in late autumn and during winter dormancy indicates an allometric effect on the degree of metabolic depression related to the size of the fat stores and suggests greater energy conservation in the smaller young.

show abstract

Section: Discussionmentioning

confidence: 99%

Seasonal metabolic depression, substrate utilisation and changes in scaling patterns during the first year cycle of tegu lizards (Tupinambis merianae)

Souza

Carvalho

Abe

et al. 2004

Journal of Experimental Biology

View full text Add to dashboard Cite

show abstract

“…Grey seals (Halichoerus grypus) have been extensively studied during their fasting and lactation period. Although there are many similarities between NES and grey seal fasting and lactation (Mellish et al, 2000(Mellish et al, , 1999aMellish and Iverson, 2001;Champagne et al, 2012b;Fowler et al, 2014), some key differences arise. Unlike NES, grey seals appear to regulate milk lipid composition through changes in LPL activity in the mammary gland (Mellish et al, 1999b;Iverson et al, 1995).…”

Section: Inter-specific Comparisons Of Fasting and Lactationmentioning

confidence: 99%

Adiposity and fat metabolism during combined fasting and lactation in elephant seals

Fowler

Champagne

Crocker

2018

Journal of Experimental Biology

View full text Add to dashboard Cite

Animals that fast depend on mobilizing lipid stores to power metabolism. Northern elephant seals (Mirounga angustirostris) incorporate extended fasting into several life-history stages: development, molting, breeding and lactation. The physiological processes enabling fasting and lactation are important in the context of the ecology and life history of elephant seals. The rare combination of fasting and lactation depends on the efficient mobilization of lipid from adipose stores and its direction into milk production. The mother elephant seal must ration her finite body stores to power maintenance metabolism, as well as to produce large quantities of lipid and proteinrich milk. Lipid from body stores must first be mobilized; the action of lipolytic enzymes and hormones stimulate the release of fatty acids into the bloodstream. Biochemical processes affect the release of specific fatty acids in a predictable manner, and the pattern of release from lipid stores is closely reflected in the fatty acid content of the milk lipid. The content of the milk may have substantial developmental, thermoregulatory and metabolic consequences for the pup. The lactation and developmental patterns found in elephant seals are similar in some respects to those of other mammals; however, even within the limited number of mammals that simultaneously fast and lactate, there are important differences in the mechanisms that regulate lipid mobilization and milk lipid content. Although ungulates and humans do not fast during lactation, there are interesting comparisons to these groups regarding lipid mobilization and milk lipid content patterns.

show abstract

“…Likewise, in lactating northern elephant seals Mirounga angustirostris, a phocid species that is adapted to abstain from food and water during lactation, the contribution of protein to energy metabolism increased as the proportion of adipose tissue decreased with time from parturition (Crocker et al 1998). Two other phocid species that fast during lactation, grey seals Halichoerus grypus and hooded seals Cystophora cristata, lost 16 and 7% of initial protein reserves, re spectively, which appeared to be related to milkprotein output (Mellish et al 1999, Mellish & Iverson 2001. Based on isotopic measurements of milk production, Oftedal (2000) estimated that 16 to 18% of maternal body protein is transferred to the offspring via milk in several species of fasting seals and bears.…”

Section: Body Components That May Contribute To Body Shapementioning

confidence: 99%

Body shape changes associated with reproductive status, nutritive condition and growth in right whales Eubalaena glacialis and E. australis

Miller

Best²,

Perryman³

et al. 2012

Mar. Ecol. Prog. Ser.

114

154

View full text Add to dashboard Cite

Mammalian reproduction is metabolically regulated; therefore, the endangered status and high variability in reproduction of North Atlantic right whales Eubalaena glacialis necessitate accurate assessments at sea of the nutritional condition of living individuals. Aerial photogrammetry was used to measure dorsal body width at multiple locations along the bodies of free-swimming right whales at different stages of the female reproductive cycle (E. glacialis) and during the initial months of lactation (mother and calf Eubalaena australis) to quantify changes in nutritional condition during energetically demanding events. Principal components analyses indicated that body width was most variable at 60% of the body length from the snout. Thoracic, abdominal and caudal body width of E. australis thinned significantly during the initial months of lactation, especially at 60% of body length from the snout, while their calves' widths and widthto-length ratios increased. The body shape of E. glacialis that had been lactating for 8 mo was significantly thinner than non-lactating, non-pregnant E. glacialis. Body shape of E. glacialis measured in the eighth month of lactation was significantly thinner than that of E. australis in the first month, but did not differ from that of E. australis in the third and fourth months. Body width was comparable with diameter calculated from girth of carcasses. These results indicate that mother right whales rely on endogenous nutrient reserves to support the considerable energy expenditure during the initial months of lactation; therefore, photogrammetric measurements of body width, particularly at 60% of body length from the snout, are an effective way to quantitatively and remotely assess nutritional condition of living right whales.

show abstract

Blood metabolites as indicators of nutrient utilization in fasting, lactating phocid seals: does depletion of nutrient reserves terminate lactation?

Cited by 22 publications

References 29 publications

Seasonal metabolic depression, substrate utilisation and changes in scaling patterns during the first year cycle of tegu lizards (Tupinambis merianae)

Seasonal metabolic depression, substrate utilisation and changes in scaling patterns during the first year cycle of tegu lizards (Tupinambis merianae)

Adiposity and fat metabolism during combined fasting and lactation in elephant seals

Body shape changes associated with reproductive status, nutritive condition and growth in right whales Eubalaena glacialis and E. australis

Contact Info

Product

Resources

About