Hello Lactnetters,

For anyone with an interest in lactation on other mammals, here is a link to
a really interesting article about lactation in whales and dolphins. It's
really fascinating and well worth printing out and reading (although it's 26
pages long!) - definitely a good way to unwind for any (budding)lactation
biologist.

Here is the link and abstract - free online.

http://www.kluweronline.com/issn/1083-3021/

Lactation in Whales and Dolphins: Evidence of Divergence Between Baleen- and
Toothed-SpeciesLactation in Whales and Dolphins: Evidence of Divergence
Between Baleen- and Toothed-Species

Although it has been more than one hundred years since the first publication
on the milks of whales and dolphins (Order Cetacea), information on
lactation in these species is scattered and fragmentary. Yet the immense
size of some cetaceans, and the recent evidence that another group of marine
mammals, the true seals, have remarkable rates of secretion of milk fat and
energy, make this group of great comparative interest. In this paper
information on lactation patterns, milk composition and lactation
performance is reviewed. Two very different patterns are evident. Many of
the baleen whales (Suborder Mysticeti) have relatively brief lactations (5–7
months) during which they fast or eat relatively little. At mid-lactation
they produce milks relatively low in water (40–53%), high in fat (30–50%),
and moderately high in protein (9–15%) and ash (1.2–2.1%). From mammary
gland weights and postnatal growth rates, it is predicted that their energy
outputs in milk are exceptional, reaching on the order of 4000 MJ/d in the
blue whale. This is possible because pregnant females migrate to feeding
grounds where they can ingest and deposit great amounts of energy, building
up blubber stores prior to parturition. On the other hand, the toothed
whales and dolphins (Suborder Odontoceti) have much more extensive
lactations typically lasting 1–3 years, during which the mothers feed. At
mid-lactation their milks appear to be higher in water (60–77%) and lower in
fat (10–30%) and ash (0.6–1.1%), with similar levels of protein (8–11%). At
least some odontocetes resemble primates in terms of low predicted rates of
energy output and a long period of dependency of the young. However, these
hypotheses are based on small numbers of samples for a relatively small
number of species. Much of the available data on milk composition is of
rather poor quality; for example, it is not possible to determine if milk
composition changes over the course of lactation among odontocetes.
Additional research on cetacean mammary glands and their secretions is
needed to understand the reproductive strategies of these fascinating
animals.

groetjes
Sara Bernard (budding lactation biologist)
The Netherlands

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