Dear Colleagues,
We are pleased to announce a new publication in the Journal of Mammalogy:
Interannual and individual variation in milk composition of New Zealand
sea lions (Phocarctos hookeri) 2012.
Federico G. Riet-Sapriza, Pádraig J. Duignan, B. Louise Chilvers, Ian S.
Wilkinson, Nicolás Lopez-Villalobos, Duncan D. S. Mackenzie, Alastair
MacGibbon, Dan P. Costa, and Nick Gales
Journal of Mammalogy, 93(4):1006-1016.
DOI: http://dx.doi.org/10.1644/11-MAMM-A-220.2
URL: http://www.bioone.org/doi/full/10.1644/11-MAMM-A-220.2
Correspondent: [email protected]
ABSTRACT: In this study 308 milk samples were collected and analyzed
from 181 individual female New Zealand sea lions (NZ sea lions;
Phocarctos hookeri) breeding on Enderby Island (Auckland Islands).
Samples were collected from the 1st part of early lactation (January and
February) over a period of 7 years (1997, 1999–2003, and 2005). The
effect of year, month, and maternal characteristics (body mass, body
condition index [BCI], and age class) on the composition of milk was
evaluated using a mixed model for repeated measures. The gross
composition (6 SD) of the milk was lipid (21.3% 6 8.1%), protein (9.4% 6
2.4%), water (67.9% 6 8.8%), ash (0.48% 6 0.06%), and energy content
(10.3 6 3.2 kJ/g). Overall, the quality of milk of the NZ sea lions in
this study was relatively lower in solids and fats than that of other
pinnipeds and, in particular, other sea lion species. There were
significant effects of year and month on the concentration of lipids in
milk, and of year and maternal age class on maternal body mass and BCI.
There were significant relationships between various maternal
characteristics and milk composition. Thus, the concentration of milk
lipids was significantly correlated with maternal BCI, body mass, and
pup age. Given that NZ sea lions are a nationally critical species in
decline, the relationship between the temporal (yearly and monthly)
variations in milk composition, maternal body mass, reproductive
success, and changes in food supply in relation to natural perturbations
or fisheries resource competition warrants further investigation to
disentangle this relationship and implement appropriate management
initiatives.
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