RESEARCH BioOne? EVOLVED Proximate Nutrient Analyses of Four Species of Submerged Aquatic Vegetation Consumed by Florida Manatee (Trichechus manatus latirostris) Compared to Romaine Lettuce (Lactuca sativa var. longifolia) Author(s): Jessica L. Siegal-Willott, D.V.M., Dipl. A.C.Z.M., Kendal Harr, D.V.M., M.S., Dipl. A.C.V.P., Lee-Ann C. Hayek, Ph.D., Karen C. Scott, Ph.D., Trevor Gerlach, B.S., Paul Sirois, M.S., Mike Renter, B.S., David W. Crewz, M.S., and Richard C. Hill, M.A., Vet.M.B., Ph.D., M.R.C.V.S. Source: Journal of Zoo and Wildlife Medicine, 41(4):594-602. 2010. Published By: American Association of Zoo Veterinarians DOI: 10.1638/2009-0118.1 URL: http://www.bioone.org/doi/full/10.1638/2009-0118.1 BioOne (www.bioone.org) is an electronic aggregator of bioscience research content, and the online home to over 160 journals and books published by not-for-profit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne's Terms of Use, available at www.bioone.org/page/terms of use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. Journal of Zoo and Wildlife Medicine 41(4): 594-602, 2010 Copyright 2010 by American Association of Zoo Veterinarians PROXIMATE NUTRIENT ANALYSES OF FOUR SPECIES OF SUBMERGED AQUATIC VEGETATION CONSUMED BY FLORIDA MANATEE {TRICHECHUS MANATUS LATIROSTRIS) COMPARED TO ROMAINE LETTUCE {LACTUCA SATIVA VAR. LONGIFOLIA) Jessica L. Siegal-Willott, D.V.M., Dipl. A.C.Z.M., Kendal Harr, D.V.M., M.S., Dipl. A.C.V.P., Lee-Ann C. Hayek, Ph.D., Karen C. Scott, Ph.D., Trevor Gerlach, B.S., Paul Sirois, M.S., Mike Renter, B.S., David W. Crewz, M.S., and Richard C. Hill, M.A., Vet.M.B., Ph.D., M.R.C.V.S. Abstract: Free-ranging Florida manatees (Trichechus manatus latirostris) consume a variety of sea grasses and algae. This study compared the dry matter (DM) content, proximate nutrients (crude protein [CP], ether-extracted crude fat [EE], nonfiber carbohydrate [NFC], and ash), and the calculated digestible energy (DE) of sea grasses (Thalassia testudinum, Halodule wrightii, and Syringodium filiforme) collected in spring, summer, and winter, and an alga (Chara sp.) with those of romaine lettuce (Lactuca sativa var. longifolia). Neutral-detergent fiber (NDF), acid- detergent fiber (ADF), and lignin (L) measured after ash-extraction were also compared. Results of statistical tests (a = 0.01) revealed DM content was higher in aquatic vegetation than in lettuce (P = 0.0001), but NDF and ADF were up to threefold greater, EE (P = 0.00001) and CP (P = 0.00001) were 2-9 times less, and NFC (P = 0.0001) was 2-6 times lower in sea grass than in lettuce, on a DM basis. Chara was lower in NDF, ADF, L, EE, CP, and NFC relative to lettuce on a DM basis. Ash content (DM basis) was higher (P = 0.0001), and DE was 2-6 times lower in aquatic vegetation than in lettuce. Sea grass rhizomes had lower L and higher ash contents (DM basis) than sea grass leaves. Based on the nutrient analyses, romaine lettuce and sea grasses are not equivalent forages, which suggests that the current diet of captive Florida manatees should be reassessed. Key words: Halodule wrightii, manatee, nutrient analysis, Syringodium filiforme, Thalassia testudinum, Trichechus manatus. INTRODUCTION longifolia) supplemented with commercial pelleted foods marketed for various other species, as well Free-ranging manatees consume more than 60 as other leafy foods (green-leaf lettuce, cabbage, species of shoreline plants and submerged aquatic endive, kale), fruits (apples), and vegetables (sweet vegetation (SAV), including sea grasses such as potatoes, carrots).119 Thalassia testudinum, Halodule wrightii, and Previous research into manatee nutrition fo- Syringodium filiforme, marine algae, and fresh- 15 1617 20 21 27 30 31 35 cused on manatee digestive morphology, phy- water algae such as Chara spp. i n siology, and efficiency, and on the types of contrast, captive manatees are fed a diet composed aquatic plants consumed.1-3-51315-17'19-20-25-27-30 Pre- principally of romaine lettuce {Lactuca sativa var. vious reports concerned with aquatic plants consumed by manatees have evaluated the From the College of Veterinary Medicine, University nutrient content of plants consumed and the of Florida, 2015 SW 16th Avenue, Gainesville, Florida variability in plant nutrient content based on 32610, USA (Department of Small Animal Hospital species, collection site, location within the com- (Siegal-Willott, Scott, Gerlach, Hill) and Department of Large Animal Hospital (Harr); Mathematics and munity, plant turnover, and time of year, but Statistics, the Smithsonian Institution, MRC-121, have not evaluated Chara algae or directly Washington, DC. 20560, USA (Hayek); the Dairy compared such data with that of romaine lettuce One Forage Laboratory, 730 Warren Road, Ithaca, in diets of captive animals.1-3-13-18-20-25-27-30 Free- New York 14850, USA (Sirois, Reuter); and the Fish ranging manatees consume entire plants of sea and Wildlife Research Institute, Florida Fish and grasses, including both rhizomes and leaves.20-27 Wildlife Conservation Commission, 100 Eighth Ave- Previous investigations found SAV to be high in nue, St. Petersburg, Florida 33701, USA (Crewz). ash and insoluble carbohydrate, and low in Present address (Siegal-Willott): Department of Animal percent protein, lipid, lignin, and soluble carbo- Health, Smithsonian National Zoological Park, 3001 6 7 9 10 27 Connecticut Avenue NW, Washington, DC. 20008, hydrates. - - - - During periods of growth, blade USA; (Harr): Idexx Laboratories, Inc.-Canada, 5645- protein levels have been shown to increase, 199 Street. Langley, British Columbia V3A 1H9, rhizome soluble carbohydrates decrease, and Canada. Correspondence should be directed to Dr. lipid levels remain relatively stable in certain Siegal-Willott ([email protected]). species of SAV.6-7-9-10 The nutrient content of sea 594 SIEGALL-WILLOTT ET AL.—NUTRIENT ANALYSES OF VEGETATION CONSUMED BY MANATEES 595 grasses also varies among species and among most shells, sand, and other biota; rinsed; and portions of the plant. Thus, entire plants of then patted dry with unbleached paper towels. each species consumed by free-ranging manatees Samples were weighed to obtain a field wet must be analyzed on several occasions through- weight and placed into plastic bags in a cooler out the year to obtain a representative evaluation that contained wet ice to protect them from light of the diet. and heat during transfer to the laboratory. In the Nevertheless, the proximate-nutrient composi- laboratory, sea grass leaf blades were manually tion of the diet of free-ranging manatees has not separated from rhizomes and some attached been compared with that of captive manatees. roots. Neither romaine lettuce nor Chara parts Differences in nutrient composition among diets were separated for analysis. Whether the two could affect captive-manatee health.19 Thus, the supermarket purchases of romaine lettuce in June aim of this study was to compare the nutrient and December were the same cultivar is not analysis of romaine lettuce with those of four known, nor is the agricultural source of the species of SAV known to be consumed regularly romaine lettuce known. Once separated, sea grass by free-ranging Florida manatees, with a view to leaves and rhizomes were weighed (laboratory improving captive-manatee nutrition. wet weight) and stored at — 80°C. Samples were lyophilized in a freeze dryer (FTS Systems Inc., MATERIALS AND METHODS Stone Ridge, New York 12484, USA) to stable weight (laboratory dry weight). Romaine lettuce SAV and romaine lettuce collection and storage and Chara samples were treated similarly to those Sea grass samples were collected under a de of the sea grasses. Percent dry matter (DM) of minimus permit issued to the Florida Fish and each sample was determined as laboratory dry Wildlife Research Institute (St. Petersburg, Florida weight X 100/laboratory wet weight. Percent DM 33071, USA). Sea grass samples were collected of leaf portion relative to rhizome portion was from two shallow-water locations in Tampa calculated as laboratory dry weight leaf/labora- Bay, Florida, adjacent to Apollo Beach (APB), tory dry weight leaf portion + laboratory dry (27°45'46N, 82°26'33W), and Sunshine Skyway weight rhizome portion) and laboratory dry causeway (SKY), (27°39'24N, 82°40'35W). Col- weight rhizome/(laboratory dry weight leaf por- lection sites were chosen where manatees are tion + laboratory dry weight rhizome portion). known to graze.17 Halodule wrightii and Thalassia testudinum were collected both at APB and SKY. Forage analysis Syringodium filiforme occurred only at SKY. Sea Proximate-nutrient analyses were performed in grass samples were collected at three time points duplicate on subsamples of each ground, lyoph- during 2006 to incorporate seasonal variations in ilized sample after thorough mixing. Sample nutrient composition: spring (March 2006), sum- moisture was measured by using near infrared mer (June 2006), and winter (December 2006). reflectance spectroscopy (Model 6500, Foss Chara sp. was collected from the Everglades North America, Eden Prairie, Minnesota 55344, National Park (ENP) (25°18'28N, 81°1'31W) in USA; AOAC method 991.01) to account for any June 2006 only; limited accessibility to ENP moisture obtained during shipment; crude pro- restricted Chara sp. collection to a single site tein (CP) was determined with an autoanalyzer and time.