In this study, the components compositions of milk from a female Pacific white-sided dolphin delivered a calf in captivity were analyzed during approximately 3 months postpartum, and the caloric value and color changes of the milk were measured for total 5 months postpartum.

 Based on the estimated values of fat, protein, carbohydrate and ash, it was shown that this milk contained high concentrations of fat and protein but low of carbohydrate. The fat content significantly changed between postpartum days 0 and 1, whereas protein and carbohydrate contents did not. The caloric value of the maternal milk, which increased from 2.3 to 3.5 kcal/g as lactation progressed, tended to be higher than that of captive bottlenose dolphins, probably due to differences in their habitats and ecological characteristics. The length and weight of the calf at birth were 105 cm and 12.9 kg, respectively, and increased linearly to 129 cm and 27.8 kg at 15 weeks postpartum.

 The color of the maternal milk started changing to greenish white at approximately 2 weeks postpartum. This phenomenon might be a characteristic of these animals, as it has been identified in other cetaceans.

 Although the present results were generated from only a single individual, they provide important basic information for understanding the ecology of Pacific white-sided dolphins and hand rearing in captivity. Further study is needed to accumulate data from more cetaceans.

Information from Secretariats