Abstract

Gestation and lactation result in metabolic alterations of the dam because of varying demands during the different stages of development of the fetus and offspring. Despite killer whales (Orcinus orca) having one of the longest gestations and highest birth weights of all mammals, these metabolic alterations and their impact on the physiology of the dam have not been measured in this species. To address this knowledge deficit, 42 hematologic and biochemical parameters from 9 female killer whales (24 pregnancies, 1,553 samples) were compared between the following stages: (1) three months prior to conception; (2) gestation, and (3) the first 12 months of lactation. Decreased hematocrit, hemoglobin and red blood cell counts were indicative of plasma volume expansion during mid and late gestation. The killer whales exhibited a progressively increasing inflammatory state leading up to parturition. Gestation and lactation caused significant shifts in the lipid metabolism. Glucose levels were low during late gestation, the period of the most rapid fetal growth. Our results demonstrate that gestation and lactation cause significant physiologic changes in the dam. Of these changes, the last 12 months of gestation had greater physiological impact than lactation, but changes associated with parturition and the puerperium period were the most dramatic. It can be expected that, during this period, female killer whales are particularly susceptible to illness, anthropogenic and environmental disturbances.

Acknowledgements

The authors would like to thank the current and former veterinary and animal training staff of SeaWorld California, Florida, and Texas for their assistance with sample collection.