Milk yield and composition in the punare Thrichomys apereoides.

1. Per cent fat composition of the milk was unusually high, ranging from 30.2 +/- 0.8% on day 2, to 21.0 +/- 1.0% on day 21. 2. Per cent protein changed significantly over time, ranging from 11.9 +/- 0.6% to 17.4 +/- 0.9%. 3. Lactose content was low, and decreased significantly over time, from 4.62 +/- 0.1% to 2.65 +/- 0.1%. 4. Milk production peaked at day 14 and ceased by day 35. 5. The unusual milk composition of this tropical rodent, is one of several adaptations correlated with reproduction in a xeric environment.