Abstract

The nutritional and immunological benefits of a mother's milk to a newborn are well documented for many species. During the last several years research has provided important information on the nutritional and chemical composition of milk from the Atlantic bottlenose dolphin (Tursiops truncatus). This information has improved the understanding of the development of calves and how to provide supplemental milk similar in composition to mother's milk if a calf is orphaned. Other research efforts have focused on the toxicological aspects of milk to determine the impact that heavy metals and other contaminants have on the mother's health, her milk and the calf's health and development. To date no research has been performed to study the immunological aspects of dolphin milk. This study was performed to determine which classes of immunoglobines, if any, are present in dolphin milk during various stages of lactation. A total of 200 milk samples from 20 Atlantic bottlenose dolphins were kindly provided by Dr. S. Ridgway from Naval Research and Development (San Diego, CA) and Dr. J. Sweeney from Dolphin Quest (Big Island of Hawaii). A total of four milk samples from a single Pacific white-sided dolphin (Lagenorhyncus obliqui dens) were kindly provided by Dr. J. Boehm from the John G. Shedd Aquarium (Chicago, EL). The stages of lactation included in these samples ranged from 21 hours through 1201 days after the birth of a calf. The samples were analyzed by immunoelectrophoresis and enzyme linked immunosorbent assay (ELISA) for the presence of immunoglobulins. Since a limited number of samples were available from the first 24-96 hours post-parturition (due to the difficulties typically encountered in obtaining samples during this period), and since the consistency of the samples was affected by their having been frozen for storage and shipping, it was not possible to reliably determine in the present study if any of the early samples represented colostrum or when the transition from colostrum to milk occurred. It is clear from the study, however, that immunoglobuhns are secreted in milk throughout lactation with IgG being the predominant class of immunoglobulins. This is the same situation present in milk samples from various ruminant species, which are evolutionarily related to cetaceans. Whether the calf benefits from the continued secretion of these immunoglobulins is not clear without further research.

Acknowledgements

The authors wish to thank Dr. S. Ridgway (NRaD), Dr. J. Sweeney (Dolphin Quest), and Dr. J. Boehm (John G. Shedd Aquarium) for their generous donation of samples for this study.