Effect of lactation stage and concurrent pregnancy on milk composition in the bottlenose dolphin

Abstract

Although many toothed whales (Cetacea: Odontoceti) lactate for 2–3 years or more, it is not known whether milk composition is affected by lactation stage in any odontocete species. We collected 64 pooled milk samples spanning 1–30 months postpartum from three captive bottlenose dolphins Tursiops truncatus. Milks were assayed for water, fat, crude protein (TN × 6.38) and sugar; gross energy was calculated. Ovulation and pregnancy were determined via monitoring of milk progesterone. Based on analysis of changes in milk composition for each individual dolphin, there were significant increases (P<0.05) in fat (in all three dolphins) and crude protein (in two of three), and a decrease (P<0.05) in water (in two of three) over the course of lactation, but the sugar content did not change. In all three animals, the energy content was positively correlated with month of lactation, but the percentage of energy provided by crude protein declined slightly but significantly (P<0.05). At mid-lactation (7–12 months postpartum, n=17), milk averaged 73.0±1.0% water, 12.8±1.0% fat, 8.9±0.5% crude protein, 1.0±0.1% sugar, 1.76±0.09 kcal g−1 (=7.25 kJ g−1) and 30.3±1.3% protein:energy per cent. This protein:energy per cent was surprisingly high compared with other cetaceans and in relation to the growth rates of calves. Milk progesterone indicated that dolphins ovulated and conceived between 413 and 673 days postpartum, following an increase in milk energy density. The significance of these observed compositional changes to calf nutrition will depend on the amounts of milk produced at different stages of lactation, and how milk composition and yield are influenced by sampling procedure, maternal diet and maternal condition, none of which are known.

Milk Composition in the Weddell SealLeptonychotes weddellii: Evidence for a Functional Role of Milk Carbohydrates in Pinnipeds

“…Regarding changes in milk composition with time postpartum, earlier studies of Weddell seal milk have been inconsistent. A progressive rise in milk fat and DM during early lactation is typical among many mammals (Oftedal 1984b), including phocid seals and cetaceans (Oftedal 1997(Oftedal , 2011West et al 2007). Data presented by Stull et al (1967) for milk collected between 1 and 18 dpp and Kooyman and Drabek (1968) for 1-35 dpp also suggest a rise in milk fat, although low numbers of samples and incomplete presentation of data make these results hard to interpret.…”

The evolution of milk secretion and its ancient origins

“…The 'crop milk' of pigeons, flamingoes and emperor penguins is a lipid-rich material produced by holocrine secretion by epithelial cells of the esophagus or crop (Horseman and Buntin, 1995), but it does not match milk in complexity, magnitude or duration of secretion. Lactation can persist for many years in humans, great apes, toothed whales, and elephants (West et al, 2007), but may be as little as 3-4 days in the ice-breeding hooded seal (Oftedal et al, 1993a).…”

Uso de gordura subcutânea como matriz biológica na dosagem de esteroides sexuais em baleias jubarte (Megaptera novaeangliae)

“…Therefore, milk could be safely used in dolphins to measure reproductive variables, such as the length of the follicular and luteal phases, the number of ovulations per year, and especially the occurrence of pregnancy . Similar results regarding hormone profiles were found seven years later when analyzing the effect of lactation stage and concurrent pregnancy on milk composition in the bottlenose dolphin (WEST et al, 2007).…”