Initial Defecation Time and Rate of Passage of Digesta in Adult Hawaiian Monk Seals , Monachus schauinslandi

In an effort to gain a better understanding of the digestive physiology of the Hawaiian monk seal, Monachus schauinslandi, we measured the initial defecation time and rate of digesta passage using chromic oxide (Cr2O3) and frozen corn kernels as markers. IDT ranged from 9.5 to 19 h (mean 14 + 4.8 h), which was a longer period of time than that reported for any other pinniped. Rate of digesta passage using a single pulse dose of Cr2O3 was approximately 39 h for two of the three seals, which is also longer than that reported for other pinnipeds. Possible reasons for these longer rates include morphological and physiological differences, age of the seals, and feeding regime. Percent Cr2O3 recovery was low (52.7-74.8%), reflecting the difficulty in collecting liquid stools. Levels of protein and ash (dry matter basis) were 21.70 and 34.79% respectively, which reflects the high protein and mineral content of the herring diet. This study has provided essential baseline data that will provide further insight into the digestive physiology of the Hawaiian monk seal.