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Author | Cherel Yves, Hobson Keith A, Guinet Christophe, | ||||
Title | Milk isotopic values demonstrate that nursing fur seal pups are a full trophic level higher than their mothers | Type | Journal Article | ||
Year | 2015 | Publication | Rapid Communications in Mass Spectrometry | Abbreviated Journal | Rapid Commun. Mass Spectrom. |
Volume | 29 | Issue | 16 | Pages | 1485-1490 |
Keywords | Animals, Animals, Suckling, Animals, Suckling: physiology, Carbon Isotopes, Carbon Isotopes: analysis, Female, Fur Seals, Fur Seals: physiology, Lactation, Male, Milk, Milk: chemistry, Nitrogen Isotopes, Nitrogen Isotopes: analysis, Nutritional Status, | ||||
Abstract | RATIONALE: In mammals including humans, mother-to-offspring transfer of nutrients has been the focus of several isotopic studies. Measurement of δ(13) C and δ(15) N values were mainly conducted on easily sampled tissues such as blood and hair that allow the calculation of apparent discrimination factors (∆(13) C and ∆(15) N) between offspring and maternal tissues. Quantifying real ∆(13) C and ∆(15) N values requires the measurement of the δ(13) C and δ(15) N values of milk, the exclusive food of newborns. Surprisingly, little isotopic information is available on milk and its biochemical components (lipids and proteins).
METHODS: Paired blood and milk samples from 10 lactating females and their pups were collected from two otariid species, the Antarctic and subantarctic fur seals. Tissue δ(13) C and δ(15) N values were measured using continuous-flow isotope ratio mass spectrometry (CFIRMS) on maternal and offspring blood, and on whole milk, lipid-free milk and milk lipids, thus allowing the calculation and comparison of apparent (maternal blood to offspring blood) and real (lipid-free milk to offspring blood) ∆(13) C and ∆(15) N values. RESULTS: In both fur seal species, the apparent ∆(13) C values averaged ~0.0 ‰. Lipid-free milk was slightly (13) C-depleted compared with both maternal and pup blood and it was strongly (13) C-enriched (~6.3 ‰) compared with milk lipids. In contrast, the apparent and real ∆(15) N values averaged 1.2-1.4 and 2.6-3.0 ‰, respectively, the differences being explained by the ~1.5 ‰ lower milk δ(15) N values than those of maternal blood. CONCLUSIONS: In fur seals, the low apparent ∆(15) N translated into a higher real ∆(15) N value, amounting to a full trophic level, which is in agreement with the almost never verified hypothesis that (15) N differences between mothers and their offsprings should reflect one complete trophic level. The study highlights the need to measure milk isotopic values to disentangle the nutritional mother-to-offspring relationships. |
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Programme | 109 | ||||
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ISSN | 0951-4198 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Notes | Approved | yes | |||
Call Number | Serial | 6170 | |||
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