Acid-Insoluble Ash As a Measure of Dry Matter Digestibility in Captive African Elephants (Loxodonta africana)

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1 Zoo Biology 24: (2005) Technical Report Acid-Insoluble Ash As a Measure of Dry Matter Digestibility in Captive African Elephants (Loxodonta africana) Christine Pendlebury, 1 Nicholas E. Odongo, 1 Alejandra Renjifo, 2 Jim Naelitz, 2 Eduardo V. Valdes, 2 and Brian W. McBride 1n 1 Department of Animal and Poultry Science, University of Guelph, Guelph, Canada 2 Disney s Animal Kingdom, Lake Buena Vista, Florida There are limited data on the diet dry matter digestibility (DMD) of captive African elephants. Although the total fecal collection method is the standard for determining DMD, it is labor-intensive, time-consuming, and expensive. The acid-insoluble ash (AIA) marker technique has been used successfully to determine DMD in ruminants and monogastrics. The objective of this study was to assess how accurately the AIA marker technique could estimate the DMD of captive African elephants (Loxodonta africana). Three mature male African elephants at Disney s Animal Kingdom in Florida were used in this study. The animals were offered a Bermuda grass hay-based ration, and the total dry matter intake (DMI) and total fecal output were measured daily over a 7-day period to determine the total collection DMD. The feed ingredients and fecal samples were also analyzed for AIA. Although there were differences (Po0.05) in total DMI and total fecal outputs, the DMD values did not (P40.05) differ ( vs for total collection and AIA, respectively). There was a linear (y ¼ x; R 2 ¼ 0.74) relationship between the total collection and AIA marker technique DMD values. These results suggest that AIA can be used to accurately estimate the DMD of captive African elephants. Zoo Biol 24: , c 2005 Wiley-Liss, Inc. Key words: captive African elephant; acid insoluble ash; dry matter digestibility Grant sponsor: Ontario Ministry of Agriculture and Food (OMAF); Grant sponsor: Natural Sciences and Engineering Research Council of Canada. Jim Naelitz s present address is Knoxville Zoological Gardens, Knoxville, Tennessee. n Correspondence to: Brian W. McBride, Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1. bmcbride@uoguelph.ca Received for publication May 7, 2004; Accepted January 13, DOI: /zoo Published online 14 June 2005 in Wiley InterScience ( c 2005 Wiley-Liss, Inc.

2 262 Pendlebury et al. INTRODUCTION The elephant is a hindgut fermenter that consumes a variety of plant species in large amounts on a daily basis [van Hoven et al., 1981]. The dry matter intake (DMI) of adult African elephants (Loxodonta africana) has been reported to be approximately % of their total body weight (BW), which ranges from 1,800 to 6,000 kg [de Villiers et al., 1991; Roehrs et al., 1989]. However, there are limited data on the diet dry matter digestibility (DMD) of captive large hindgut fermenters such as elephants and rhinoceroses [Clemens and Maloiy, 1983; Clauss et al., 2003]. Although the total fecal collection method is the standard for determining DMD, it is labor-intensive, time-consuming, and expensive [Hackenberger, 1987]. Because the data regarding the DMD of captive elephants are limited, the domestic horse has been used as the nutritional model [Oftedal et al., 1996]. However, although the horse and elephant are both hindgut fermenters with a functional caecum, this comparison has been found to be misleading and inaccurate [Clauss et al., 2003]. Elephants have a faster passage rate and a higher rate of digestion than horses [Clauss et al., 2003]. There is therefore a need to establish a faster, less time-consuming, and less expensive method to accurately determine the DMD of captive elephants. The acid-insoluble ash (AIA) marker technique has been used successfully to determine DMD. Therefore, the objective of this study was to assess how accurately the AIA marker technique could estimate the DMD of captive African elephants. MATERIALS AND METHODS Animals Three mature male African elephants housed at Disney s Animal Kingdom in Florida were used in this study. Elephant 1 was B33 years old, elephant 2 was B23 years old, and elephant 3 was B27 years old. The elephants weighed 5,153, 3,865, and 4,531 kg, respectively, at the beginning of the trial. During the trial, the elephants were housed individually in indoor stalls ( m) and rotated through outdoor vestibules ( m) that led to an outside yard. The floors of the indoor stall and vestibule were concrete, whereas the outdoor yard (1,610 m 2 ) had a sugar sand dirt substrate floor and was completely free of vegetation. Diet Preparation and Feeding The animals were offered a Bermuda grass (Cynodon dactylon) hay-based ration as shown in Table 1, and the total DMI and total fecal output were measured daily over a 7-day period to determine the total collection DMD. The chemical composition of the feed ingredients is shown in Table 2. Hay was delivered daily to the elephant barn, weighed, and kept at room temperature in a hallway. Browse was stored in an outdoor walk-in cooler at 101C. Bundles of pennisetum grass (Pennisetum purpureum) were delivered every 3 4 days, weighed, and fed out daily. Arundo grass (Arundo donax), corn stalks and leaves (Zea mays indentata), and the leaves and trunk of banana trees (Musa acuminata) were provided as available

3 Dry Matter Digestibility of Captive Elephants 263 TABLE 1. Dietary ingredients offered as a percent of total diet for captive African elephants (DMB, Mean values for three animals) % of Diet offered Mazuri s elephant supplement a 8.4 Bermuda grass hay (Cynodon dactylon) 74.0 Pennisetum grass (Pennisetum purpureum) 15.0 Banana leaves (Musa acuminata) 0.7 Corn stalks/leaves (Zea mays indentata) 0.3 Arundo grass (Arundo donax) 0.2 Apples 0.3 Carrots 0.3 Sweet potato 0.9 Grapefruit o0.1 a Due to unavailability, Mazuri ADF 16 was substituted during one day for one elephant. TABLE 2. Dry matter, crude protein, and neutral detergent fiber (% DM) for the feed ingredients Dry matter (%) Crude protein (%) NDF (%) Mazuri s elephant supplement Mazuri s ADF 16 Pellets Corn stalks/leaves Bermuda grass hay Mazuri s primate biscuit Arundo grass Pennisetum grass Apples Carrots Sweet potato Grapefruit Banana leaves NDF, Neutral detergent fiber. from Disney Animal Kingdom s horticulture farm. Preweighed amounts of pelleted feeds (8.5 kg/day) were placed on the holding floor (half after the morning bathing routine ( hr) and half during the evening check-up ( hr)). Produce was chopped unpeeled, distributed at random into buckets the day before feeding, refrigerated overnight, and fed the following day. Water was available to the animals at all times. Sample Collection and Analysis Feed, orts, and fecal samples were collected daily; placed in reclosable freezer bags; labeled with the elephant s name, collection date, and location (stall/vestibule or yard); and frozen at 211C for later analysis. The samples were dried in a forage oven (Hotpack, model ) at 1001C for 48 hr, and representative samples from each collection period were sent to Cornell University s Nutritional and Environmental Analytical Services (NEAS) for nutrient analysis (crude protein (CP), crude fat, crude fiber, ash, neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin, minerals (Ca, P, Mg, Na, and K), gross energy, and sugars (glucose, fructose, and sucrose).

4 264 Pendlebury et al. The feed ingredients and fecal samples were also analyzed for AIA using a modification of the 2N HCI procedure described by van Keulen and Young [1977]. The total fecal collection DMD was calculated as (dietary intake fecal output) n 100)/dietary intake. The AIA DMD was calculated as the ratio of AIA in the feed and feces [van Soest, 1994]: % AIA DMD ¼ (% marker in feed/% marker in feces) (% nutrient in feces/% nutrient in feed). Statistical analysis was conducted with the use of SAS 8.2 [SAS, 2002], and effects were considered significant at Po0.05. RESULTS AND DISCUSSION At the end of the trial, elephants 1 3 weighed 5,216 kg, 3,760 kg, and 4,432 kg, respectively. Elephant 1 consumed on average 1.7% of its BW in feed daily, and was the only elephant that gained weight during the trial. Elephant 2 consumed 1.5% of its BW in feed daily, and elephant 3 consumed 1.6% of its BW in feed daily. These DMI (% BW) are consistent with the findings of Clauss et al. [2003], who compared digestibility data for African and Asian elephants from the literature and reported a DMI (% BW) range of on hay-based diets. Elephant 1 consumed more (Po0.05) feed and had a greater (Po0.05) fecal output than elephants 2 and 3 (Table 3). There were no differences (P40.05) between the total collection and AIA DMD values ( vs , respectively). These DMD values are consistent with those reported by Roehrs et al. [1989], but lower than the 45.9% reported by Tomat et al. [1999]. The higher DMD in the Tomat et al. [1999] study is attributable to the higher proportion (50%) of Toronto Zoo Fibre Plus Herbivore diet (12.7% CP, 3.72 kcal/g GE, 8.6% ADF, and 15.2% NDF on a DM basis) included in the diet. There was a linear (y ¼ x; R 2 ¼ 0.74) relationship between the total collection and AIA marker technique DMD values (Fig. 1). The AIA DMD was slightly higher than the total fecal collection DMD. This may be accounted for by soil contamination when the feces were collected from the outdoor yard. Soil contamination has been shown to be one of the shortcomings of the AIA method [Kotb and Luckey, 1972]. CONCLUSIONS Because of the enormous amounts of matter excreted by captive elephants on a daily basis, it is expensive, labor-intensive, and time-consuming to determine DMD TABLE 3. Mean feed intake, fecal output, and diet dry matter digestibility (7SEM) of three captive African elephants Elephant # 1 Elephant # 2 Elephant # 3 Feed intake, kg 89.5 (2.86) 57.7 (2.66) 72.3 (2.76) Fecal output, kg 57.3 (2.25) 37.2 (2.04) 47.9 (2.09) Total collection DMD, % 36.0 (0.72) 35.6 (0.72) 33.7 (0.72) AIA DMD, % 38.4 (0.72) 36.8 (0.72) 36.0 (0.72) SEM, standard error of mean; DMD, dry matter digestibility; AIA, Acid insoluble ash.

5 Dry Matter Digestibility of Captive Elephants Total collection DMD (%) y = x R 2 = Acid insoluble ash DMD (%) Fig. 1. Relationship between total collection DMD and AIA DMD. using the total collection method. The current results suggest that an AIA marker technique can be used to accurately estimate the DMD of captive African elephants. ACKNOWLEDGMENTS The authors thank the Elephant Team staff of Disney s Animal Kingdom for their cooperation. This study was supported in part by a grant to B.W.M. from the Natural Sciences and Engineering Research Council of Canada. REFERENCES Clauss M, Loehlein W, Kienzle E, Wiesner H Studies on feed digestibility in captive Asian elephants (Elephas maximus). J Anim Physiol Anim Nutr 87: Clemens ET, Maloiy GMO Nutrient digestibility and gastrointestinal electrolyte flux in the elephant and rhinoceros. Comp Biochem Physiol 75A: de Villiers PA, Pietersen EW, Hugo TA, Meissner HH, Kok OB Method of sampling food consumption by free-ranging elephant. S Afr J Wild Res 21:23 7. Hackenberger MK Diet digestibilities and ingesta transit times of captive Asian (Elephas maximus) and African (Loxodonta africana) elephants. Master s thesis, University of Guelph, Guelph, Ontario. Kotb AR, Luckey TD Markers in nutrition. Nutr Abstr Rev 42: Oftedal OT, Baer DJ, Allen ME. 1996: The feeding and nutrition of herbivores. In: Kleimann DG, Allen ME, Thompson KV, Lumpkin S, editors. Wild mammals in captivity: principles and techniques. Chicago: University of Chicago Press. p Roehrs JM, Brockway CR, Ross DV, Reichard TA, Ullrey DE Digestibility of timothy hay by African elephants. Zoo Biol 8: SAS. User s guide. Statistics, version 8.2 edition. Cary, NC: SAS Institute, Tomat L, Schumann B, Atkinson JL, Valdes EV Digestibility studies with captive African elephants (Loxodonta africana) [Abstract]. In: Proceedings of the 1st European Zoo Nutrition Meeting, Rotterdam, The Netherlands. p 76. van Hoven W, Prins RA, Lankhorst A Fermentative digestion in the African elephant. S Afr J Wild Res 11: van Keulen J, Young BA Evaluation of acid-insoluble ash as a natural marker in ruminant digestibility studies. J Anim Sci 44: van Soest PJ Nutritional ecology of the ruminant. 2nd ed. Ithaca, NY: Comstock Publishing Associates. p