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Title: The effect of changes in dietary fat level on body composition, blood metabolites and hormones, rate of passage, and nutrient assimilation efficiency in harbor seals 
Author: Stanberry, Kathryn
Date: 2003-12
Publisher: University of Hawaii at Manoa
Abstract: The focus of this study was to determine the effect of dietary fat content on assimilation efficiency (AE) in harbor seals. Rate of passage (peak at 24h) and initial defecation times (mean of 13.0h) were initially measured in five harbor seals on a typical high fat herring diet. Five harbor seals were used to assess the intake and nutrient digestibility of both high- and low-fat herring diets during the last 72 h of a 4-week feeding trial. The AE was determined using chromic oxide (Cr2O3 at 0.3% of the DM; placed in gel capsules and inserted into the opercular cavity of multiple herring) as the inert marker of indicator technique. All diet and fecal samples were analyzed for dry matter, ash, crude protein, and crude fat content. Carbohydrate and energy components were then calculated. Initial defecation times were longer than those found in previous studies at 13.0 ± 7.5h. Initial defecation times were found to be negatively correlated (r2= 0.85) to the total number of defecations. Percent Cr2O3 recovery was high at 85.33 ± 11.36%. Recovery of chromic oxide over 48 hours followed the expected bell-shaped curve with peak Cr2O3 recovery at ~24h after feeding. Assimilation efficiency of dry matter was significantly higher (p=0.0006) for the high fat herring, but AE's of crude protein, crude fat, and energy were similar between the two diets. This study confirms that fat content of herring does not affect nutrient AE's significantly when fed to harbor seals, but does have a significant (p=6.8*10-5 and 3.15*10-14) impact on the quantity of protein and fat consumed daily. The similarity of AE values of the high and low fat herring found in this study suggests that AE may be more dependent on prey species than was previously thought, and less dependent on the varying nutrient composition of any particular type (or kind) of prey. Further research should be conducted during both the cold and warm seasons to assess differences and determine relationships between level, type and proportion of nutrient intake on AE and animal energetic efficiency. These studies should mimic the nutritional circumstances in the wild in order to gain the best understanding of a possible relationship between nutrition and the decline of harbor seals populations.
Description: viii, 109 leaves
Rights: All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.

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