[MARMAM] new paper on milk composition of New Zealand sea lions

Federico Riet frietsapriza at gmail.com
Mon Nov 19 18:21:09 PST 2012

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: frietsapriza at gmail.com

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 

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