Natural Browse Research Articles

Feed intake, diet utilization, and composition of browses consumed by the Sumatran rhino (Dicerorhinus sumatrensis) in a North American zoo

The Sumatran rhino (Dicerorhinus sumatrensis), presently indigenous to the Malay peninsula and the islands of Sumatra and Borneo, is faced with extinction. It is estimated that fewer than 400 individuals still exist in the wild. In response, concerted efforts have been made to maintain and breed this species in captivity, and proper diet and nutrition underlie reproduction. The present feeding trial characterizes a diet fed to three Sumatran rhinos at the Cincinnati Zoo and Botanical Garden. The diet consists of mixed alfalfa/orchard grass hay, a variety of browses, grain pellets, produce (apples and bananas), and a vitamin E supplement. All three rhinos maintained body weight (614–761 kg), regular patterns of bowel movements, and fecal consistency and composition throughout the three 5-day trials. Dry matter intake (DMI) ranged from 1.40 to 2.49% of body mass. Browse contributed by far the majority of nutrients to the diets in this study, from 62 to 83% of DMI. The nutrient composition of six species of subtropically grown browses (two from differing locations, for a total of eight browses characterized) showed that leaves did not differ from twigs in water or lignin content, but leaves contained higher concentrations of protein (both crude and bound) and ash, as well as lower fiber fractions. Of the macrominerals analyzed, only phosphorus differed between leaves and twigs, with twigs containing significantly more. No differences were seen between leaves and twigs in iron, molybdenum, or zinc content, but leaves contained lower concentrations of copper and higher concentrations of manganese and selenium compared with twigs from the same plants. Dry matter digestibility averaged approximately 50%. The only overt imbalances detected when comparing rhino diets with nutrient recommendations for domestic equids were excess calcium relative to phosphorus intake and low copper intake. These data, combined with information on native browse composition, intake, and digestibility, should greatly assist in providing suitable diets for this highly endangered species. Zoo Biol 19:169–180, 2000. © 2000 Wiley-Liss, Inc.

Feed intake, diet utilization, and composition of browses consumed by the Sumatran rhino (Dicerorhinus sumatrensis) in a North American zoo

The Sumatran rhino (Dicerorhinus sumatrensis), presently indigenous to the Malay peninsula and the islands of Sumatra and Borneo, is faced with extinction. It is estimated that fewer than 400 individuals still exist in the wild. In response, concerted efforts have been made to maintain and breed this species in captivity, and proper diet and nutrition underlie reproduction. The present feeding trial characterizes a diet fed to three Sumatran rhinos at the Cincinnati Zoo and Botanical Garden. The diet consists of mixed alfalfa/orchard grass hay, a variety of browses, grain pellets, produce (apples and bananas), and a vitamin E supplement. All three rhinos maintained body weight (614–761 kg), regular patterns of bowel movements, and fecal consistency and composition throughout the three 5-day trials. Dry matter intake (DMI) ranged from 1.40 to 2.49% of body mass. Browse contributed by far the majority of nutrients to the diets in this study, from 62 to 83% of DMI. The nutrient composition of six species of subtropically grown browses (two from differing locations, for a total of eight browses characterized) showed that leaves did not differ from twigs in water or lignin content, but leaves contained higher concentrations of protein (both crude and bound) and ash, as well as lower fiber fractions. Of the macrominerals analyzed, only phosphorus differed between leaves and twigs, with twigs containing significantly more. No differences were seen between leaves and twigs in iron, molybdenum, or zinc content, but leaves contained lower concentrations of copper and higher concentrations of manganese and selenium compared with twigs from the same plants. Dry matter digestibility averaged approximately 50%. The only overt imbalances detected when comparing rhino diets with nutrient recommendations for domestic equids were excess calcium relative to phosphorus intake and low copper intake. These data, combined with information on native browse composition, intake, and digestibility, should greatly assist in providing suitable diets for this highly endangered species. Zoo Biol 19:169–180, 2000. © 2000 Wiley-Liss, Inc.

Compensatory effect of the heat increment of feeding on thermoregulation costs of white-tailed deer fawns in winter

For northern white-tailed deer (Odocoileus virginianus) fawns, the energetic cost of thermoregulation (HcE) during severe winters can result in substantial catabolism of body-tissue reserves. The heat increment of feeding (HiE) has the potential to offset thermoregulatory energy expenditure that would otherwise require the catabolism of these reserves. During winters 1996 and 1997, we conducted 18 fasting and 18 on-feed heat-production trials using indirect respiration calorimetry in a metabolic chamber. Nonlinear regression analysis was used to estimate the lower critical temperatures (Tlc) and determine the fasting metabolic rate (FMR) and resting metabolic rate (RMR). Resulting models were used to calculate HiE, HcE, and percent substitution of HiE for HcE. For fawns fed a natural browse diet, estimated FMR and RMR were 352 and 490 kJ·kg body mass (BM)-0.75·d-1, respectively; this 40% increase in thermoneutral heat production reduced Tlc from -0.8 to -11.2°C between the fasted and fed states, respectively, and reduced HcE by 59% for fed fawns. For fawns fed a concentrate diet, estimated FMR and RMR were 377 and 573 kJ·kg BM-0.75·d-1, respectively. Level of browse intake had a significant effect on RMR andTlc. RMR was 12% higher for fawns on a high versus a low level of intake, and estimated Tlc was -15.6 and -5.8°C, respectively. Our data indicate that the energetic cost of thermoregulation is probably a minor portion of the energy budget of a healthy fawn consuming natural forage.

Nutritional Profile and Leaf Surface Structure of Some Native Shrubs Consumed by Small Ruminants in Semiarid Regions of Northeastern México

Ramírez, R.G., Hernández-Piñeiro, J.L. and Maiti, R.K. 1997. Nutritional profile and leaf surface structure of some native shrubs consumed by small ruminants in semiarid regions of northeastern Mexico. J. Appl. Anim. Res., 11: 145–156. This study evaluated browse composition of animal diets of range goats and white-tailed deer (Odocoileus virginianus, texanus) grazing in northeastern Mexico and some dominant native browse species from semiarid Nuevo León, Mexico, were studied to determine their nutritional value and leaf surface ultrastructure. Browse was the main component of the annual diets of goats and deer. Large differences in nutritional vlaues were found in the different plant species, although all were high in crude protein (range = 12.3–23.5%) and low in cell wall (range = 27.7–44.7%). Plants such as Acacia rigidula, Acacia berlandieri, Ziziphus obtusifolia, Porlieria angustifolia, Condalia obovata and Acacia farnesiana showed smooth and waxy leaf surface with the absence of trichomes. These plants had acceptable digestibility values ranging from 50 to 85%, with exception of Acacia rigidula (31%), probably because of its high tannin content. However, this plant was the most prefered for its high abundance in the range. The preference in diets by small ruminants not only depends on the leaf surface structure, but is highly related to the abundance of browse species in the harsh summer season also as well as their nutritional value. It seems that availability and the high nutritional value of plants had influenced diet selection, although leaf surface smoothness may play some role in animal selection. Besides, leaf surface structure could be an acceptable guide for plant species identification.

Role of plant defense in the utilization of native browse in southern Ethiopia

Browse is an important forage in pastoral systems, especially during dry seasons, because it is high in nitrogen and digestibility. However, browse palatability may be reduced by possible plant defenses such as tannins and physical attributes. Chemical and physical properties of 20 browse species were correlated with the feeding preference of camels, sheep and goats during wet and dry seasons in a densely wooded, semi-arid savanna. Preference was assessed by comparing relative use with abundance of browse species. Chemical components included nitrogen, available nitrogen, acid-detergent fibre, in vitro digestibility, total tannins and condensed tannins. Physical defenses included thorns, hooks, spines, and leaf surface properties. Animal preference was negatively related to chemical and physical defense factors, positively related to N content, and unrelated to fibre and digestibility with results depending on animal species and season. Understanding the physical and chemical factors which influence browse selectivity aids in identifying promising forage resources.

Annual variation in white-tailed deer damage in commercial nurseries

White-tailed deer ( Odocoileus virginianus) can cause substantial damage in commercial plant nurseries by browsing plants during the winter. Variation in the severity of deer browsing was studied at eight commercial nurseries in Connecticut for 5–8 years to examine if deer damage could be predicted from historic levels at the same nursery. We found that deer damage could be predicted with some accuracy when 2 or more years of data were available for that nursery. We also assessed several independent variables including local deer densities, the availability of native browse, or winter weather conditions to determine if any correlated with annual changes in deer damage at each nursery. If so, measurement of that variable could be used to predict years when heavy levels of deer damage could be expected, allowing preventative steps to be taken. However, yearly levels of deer browsing at individual nurseries were not associated with any of these variables. There was a similar region-wide pattern in annual deer damage that was not associated with yearly snowfall levels or winter degree days.

Screening forage and browse legumes germplasm to nutrient stresses: III. Tolerance of Sesbania to aluminum and low phosphorus in soils and nutrient solution

Abstract Sesbania, particularly Esnabia sesban species, grow naturally in many parts of Africa where they form natural browse. Productivity of Sesbania as animal feed is widely limited by soil acidity and low P. In this study, eighteen ILCA accessions of S. sesban and two of S. goetzei, all but two from Africa, were evaluated for tolerance to acidity and low P on two Ethiopian soils as well as their tolerance to Al and response to P in nutrient solutions. The treatments were 0 and 4000 mg CaCO3/kg (pH 4.8 and 5.6) in combination with 0 and 37.5 mg P/kg on a Soddo Nitosol. On the Chencha clay loam with 77% Al saturation, the pH values were 4.1 (unlimed) and 5.9 (limed) in combination with 0 and 25 mg P/kg on the unlimed soil plus 37.5 mg P/kg on the limed soil. Treatments applied to the nutrient solutions were 0, 3, and 6 ppm (0, 111, and 222 μM) Al in combination with 5 and 200 μM (155 and 6200 ppm) P as KH2PO4. On the Soddo soil, Sesbania responded primarily to P which increased average shoot growth by 1...

Cultivated and Native Browse Legumes as Calf Supplements in Ethiopia

Efficient use of roughages is important for calf management in the Boran pastoral system. Using local legumes as protein supplements may improve fiber utilization and thus be an appropriate intervention. Fruits (pods and seeds) of Acacia tortilis (Forsk.) Hayne subsp. spirocarpa (Hochst. ex A. Rich) Brenan, leaves of A. brevispica (Harms), and cowpea [Vigna unguiculata (L.) Walp] hay were compared with alfalfa (Medicago sativa L.) hay as protein supplements for calves using 2 approaches. Sheep fed native grass hay under confinement were used for a controlled evaluation in growth and metabolism trials. Calves grazing dry-season forage under simulated pastoral management provided in evaluation under field conditions. All supplements increased (P 0.05) among all groups of supplemented sheep. Compared to alfalfa and cowpea diets, tanniniferous Acacia diets had a negative effect (P<0.05) on true-N digestibility, but this was offset by their positive effect (P<0.05) on reducing loss of urinary N. The A. tortilis diet had a lower (P<0.05) true-N digestibility than the A. brevispica diet, which was probably influenced by soluble phenolics in pods and seeds. On a nutritional basis these Acacia and cowpea materials are suitable for inclusion in improved feeding systems for Boran calves.

Use of native browse by Fulani cattle in central Nigeria

Shrubs and trees browsed by Fulani pastoralists' cattle in two areas of central Nigeria were identified by means of interviews with the pastoralists and observations of browsing cattle. Thirty-nine plant species were identified, many of them indigenous economic trees. The species were ranked by pastoralists according to importance in cattle diet. Chemical analyses of plant parts eaten and investigation of frequency of occurrence of the species in the study areas revealed that the pastoralists' ranking reflected not only the plants' relative abundance but also their nutritive value.

Seasonal thyroid hormone levels of free-ranging white-tailed deer (Odocoileus virginianus) in Ontario

Blood samples from killed and livetrapped deer of southern and central Ontario were analyzed for thyroxine (T4) and triiodothyronine (T3). Mean seasonal levels for six sex-age classes of deer ranged from 150 to 400 ng/dL (T3) and from 6.0 to 18.0 μg/dL (T4). Seasonal variation of T4 was less pronounced than that of T3. Both hormones decreased in the fall as compared with spring and summer, especially in yearling and older bucks. T3 values were also low in the winter but increased in spring and summer for most tested categories of deer. Differences in seasonal T3 and T4 concentrations were found between male and female deer older than 1 year, and among sex-age classes of the same sex. Regional differences in thyroid hormone levels suggested a latitudinal gradient, with higher values in southern than in central Ontario. Hormone of artificially fed deer were elevated when compared with animals that consumed only natural browse. Hormone levels were also higher in deer provided with food supplements of higher protein content. Extremely low winter T3 and T4 concentrations were found in malnourished deer. It is concluded that thyroid hormones in deer blood are influenced by current food intake and quality of nutrition. The potential for T3 and T4 as indicators of range quality is discussed.

Management Implications of Foraging Theory: Evaluating Deer Supplemental Feeding

I conducted an experiment in a northern deer yard to compare the foraging behavior of naturally wintering and supplementally fed white-tailed deer (Odocoileus virginianus) and to assess when supplemental feeding might be warranted. Deer survived on natural browse an 1 area of the yard and were provided ad libitum supplemental feed in another. I examined the effects of browse depletion and accumulating snow on diet selection in 3 winter sampling periods. I used an optimal foraging model to predict the diet for 2 potential strategies: 1) energy maximization, where deer maximize their energy intake to maximise survivorship, and 2) time minimization, where deer satisfy energy need in the least feeding time thereby minimizing exposure to deleterious climate. Deer selected energy maximizing diets in all time periods and feeding areas. Naturally wintering deer were expected to select a mixed diet of coniferous and deciduous browse. Predicted diets (deciduous:conifer) for the 3 time periods were 1,130:46, 780:330, and 589:462 g dry mass per day. Observed diets for the same time periods were 1,090:65, 684:317, and 452:490 g dry mass per day. Naturally wintering deer satisfied requirements for survival, so supplemental feed was not required for winter conditions during the study. Supplementally fed deer were expected to eat only supplemental feed in all sampling periods. Contrary to predictions, they continued to eat browse. A sensitivity analysis, used to examine the reliability of model predictions because of variable parameter estimates, indicated the model predictions were robust. Thus, I concluded that the supplemental feeding program may have been inefficient. Supplemental feed was delivered in a few large feeders, which created a limiting resource. This probably increased competition at feeders, forcing individuals to browse

Suitability of a Formulated Ration for Moose

A formulated ration for maintenance or experimental purposes has been developed for moose (Alces alces). It contains 12.7% crude protein and a digestible energy concentration of 2.4 kcal/g. Metabolizable energy concentration is 2.1 kcal/g. Performance was measured over 5 years with data from 11 moose. Daily gain in calves from weaning in August through October and November through April was 0.9 kg ? 0.06 (SE) and 0.4 kg ? 0.03 (SE), respectively, and exceeded those of wild moose. Mean body weights of adult males and females on the diet were greater than those of wild moose. Reproductive performance was also excellent with 83.1% of yearling females breeding and producing a calf at age 2. The ration has been used as the only food of moose for up to 5 years with no apparent adverse affects. It lends itself to constituent alteration for experimental purposes. J. WILDL. MANAGE. 49(1):137-141 Moose management based on sound biological knowledge requires a basic understanding of the animal and its environment. Animal welfare, whether it is measured as growth, reproductive performance, or survival is dependent upon adequate nutrition. The literature is replete with food-habits studies (Peek 1974), and several investigators have evaluated the nutritive quality of moose forage. Considerably less is known or understood about the nutritional requirements of moose. Except for recent studies by Hjeljord et al. (1982), no evaluation of food has been done using in vivo techniques. Of all mammals, ruminants have the most differentiated, specialized, and complex stomach (Hoffman 1973:1). Of the 142 ruminant species (Simpson 1945) living today, we have a poor understanding of the nutritional requirements of all but the three domesticated species (cattle, sheep, goats). Zoos have been successful in maintaining many species of wild animals on formulated diets (Crawford 1968, Rechcigl 1977), but until now, maintenance of moose has been difficult and expensive. Animals were held in enclosures containing enough natural forage to support them (LeResche and Davis 1973), or natural foods were harvested and fed to moose in confinement (Speidel 1965, Miquell and Jordan 1979, Hjeljord et al. 1982, Miquell 1983). Attempts to feed moose diets commonly fed to other cervids have largely failed (Thorne 1979). Because of an apparent difference in dietary physiology, moose do poorly on diets composed f roughage in the form of long hays (Schwartz et al. 1980). This problem has been apparently solved by the inclusion of sawdust in our ration. A major objective of our moose nutrition studies required that captive moose be maintained on a diet that was: (1) readily available; (2) inexpensive; (3) reproducible; (4) suitable to constituent alteration; and (5) able to meet nutritional requirements. This made it necessary to use a formulated ration rather than natural browse. An extensive review of the literature, plus a survey of zoos and wildlife research facilities, revealed that no such ration had been identified. Here we discuss a formulated ration for moose that meets the above criteria. Preliminary discussion and background information were previously presented (Schwartz et al. 1980). We thank M. A. Schwartz, D. Johnson, and D. C. Johnson for help with animal care and digestion experiments and D. E. Ullrey, K. B. Schneider, and S. R. Peterson for early reviews of the manuscript. Funding for these studies was provided in part by the Morris Anim. Found. and from Fed. Aid in Wildl. Restoration, Proj. W-17 and W-21. We thank the Milwaukee Co. Zoo and H. Evans for providing us with Fiberite (American Excelsior Co., Arlington, Tex.) for our earlier studies.

Use of Browse by White-Tailed Deer in an Enclosure in New Brunswick

Natural browse use by white-tailed deer (Odocoileusvirginianusborealis Miller) was measured in the fall of two consecutive years using captive animals in enclosures located in regenerative stands. Oven dry twig weight prediction equations were first established for each species in the area, and browse use measured weekly by counting the number of twigs removed. Average daily browse use amounted to 0.75 kg for fawns and to 0.80 kg for adults. Shadbush (Amelanchier spp.) and willow (Salix spp.) were highly preferred by the fawns; lambkill (Kalmiaangustifolia L.), red maple (Acerrubrum L.), and withe-rod (Viburnumcassinoides L.) were preferred by the adults. A shift towards use of conifers by fawns was observed in relation with the appearance of snow. No discernible lasting damage to regeneration of commercial species was noticed even at a browsing pressure evaluated at 2–3 times the normal level.

Rumen microbial ecology in mule deer.

Mule deer rumen microbial populations from animals in the natural habitat in Utah and from captive deer fed various rations were studied. The microorganisms were characterized on the basis of morphology and Gram reaction. Rumen samples contained 13 identifiable types of bacteria and one genus of ciliate protozoa (Entodinium). Highest rumen bacterial populations were produced on rations containing barley. No differences in proportions of ruminal bacteria in the various morphological groups could be detected when animals were fed either natural browse plants or alfalfa hay. The total numbers of bacteria were similar for animals feeding on controlled diets of browse or hay and those in the natural habitat. Numbers of some bacterial types were directly related to ciliate protozoal numbers, whereas others were inversely related. Highest rumen ciliate protozoal populations were observed on rations containing barley. No differences in protozoal populations were noted between diets containing only browse or hay. Seasonal variations were noted in ciliate protozoal numbers from deer feeding in the natural habitat. The total number of ciliate protozoa decreased in the fall and winter and remained low until spring. There were indications that salt in the deer diet favorably affected rumen ciliate protozoa. Rather than revealing direct deer management applications, this study serves to stimulate and illuminate new approaches to research in range and wildlife nutrition.

Influence of Temperature and Leachate on Germination of Atriplex polycarpa1

AbstractDesert saltbush, Atriplex polycarpa, a valuable native browse plant, occurs on dry rangeland in central and southern California. Germination was determined at temperatures from 5 to 35C at 5° intervals. Highest germination occurred at 20C on the 5th day in germinators and at 15C after 14 and 30 days. Germination declined uniformly from the 15 or 20C level to lowest and highest temperatures.For treatment A one set of seed and blotters was moistened with tap water for duration of 30 days. In treatment B the seed was soaked (leached) for 48 hours; then tap water was used to keep blotters and seed moist. In treatment C seeds were kept moist by using the leachate from the seed that had been soaked. Highest germination occurred after treatment B; lowest after treatment C; and treatment A was between C and B in effectiveness. The presence of some undetermined substances in the leachate severely inhibited germination in treatment C. Partial removal of the leachate from the seed enhanced germination in treatment B.

Rumen Microbial Ecology in Mule Deer1

Mule deer rumen microbial populations from animals in the natural habitat in Utah and from captive deer fed various rations were studied. The microorganisms were characterized on the basis of morphology and Gram reaction. Rumen samples contained 13 identifiable types of bacteria and one genus of ciliate protozoa (Entodinium). Highest rumen bacterial populations were produced on rations containing barley. No differences in proportions of ruminal bacteria in the various morphological groups could be detected when animals were fed either natural browse plants or alfalfa hay. The total numbers of bacteria were similar for animals feeding on controlled diets of browse or hay and those in the natural habitat. Numbers of some bacterial types were directly related to ciliate protozoal numbers, whereas others were inversely related. Highest rumen ciliate protozoal populations were observed on rations containing barley. No differences in protozoal populations were noted between diets containing only browse or hay. Seasonal variations were noted in ciliate protozoal numbers from deer feeding in the natural habitat. The total number of ciliate protozoa decreased in the fall and winter and remained low until spring. There were indications that salt in the deer diet favorably affected rumen ciliate protozoa. Rather than revealing direct deer management applications, this study serves to stimulate and illuminate new approaches to research in range and wildlife nutrition.

Evaluation of Two Mammal Repellents Applied to Browse Species in the Black Hills

Two mammal repellents, ZAC (zinc dimethyldithiocarbamate cyclohexylamine complex) and TMTD (tetramethylthiuram disulfide) were applied to selected browse species in the Black Hills of South Dakota. Protection was tested by measuring current annual twigs removed during the period of winter use by white-tailed deer (Odocoileus virginianus) and mule deer (0. hemionus). The repellents effectively protected chokecherry (Prunus virginiana), American plum (Prunus americana), aspen (Populus tremuloides), and caragana (Caragana arborescens) from deer browsing. Use by deer on untreated native chokecherry plants varied from 21.8 to 43.9 percent, with a mean of 28.9 percent; use of TMTD-treated plants varied from 2.1 to 17.4 with a mean of 6.8 percent, and use of ZAC-treated plants varied from 0.3 to 1.8 with a mean use of 0.7 percent. Both repellents protected aspen shoots almost as effectively as caging. ZAC was also applied to caragana and plum nursery transplants, and significantly prevented browsing by deer. Mammal repellents provide an alternative to expensive and laborious fencing and caging of experimental plants and plots, and also may be useful in browse revegetation projects. Revegetation of game ranges in the Black Hills of South Dakota frequently has been restricted because newly established plants were consumed before they were large enough to withstand browsing. Large herds of white-tailed deer and smaller herds of mule deer have damaged the browse resource in large portions of winter range areas in the central and northern Black Hills (Berner 1955, Bever 1959). Expensive deer-proof fencing often has been the only way to insure protection for small-scale experimental plantings. Large-scale pilot plantings have not been protected, owing to the great expense. The purposes of this study were (1) to determine if mammal repellents developed for the protection of conifer plantations and commercial orchards also could effectively protect native and planted browse sp cies, and (2) to compare the effectiveness of two commercially available repellent formulations under Black Hills condi-

Previous Diet of Deer, Cattle, and Sheep and Ability to Digest Alfalfa Hay

The capacity of rumen microorganisms of deer, cattle, and sheep on different diets to digest alfalfa hay was tested in an artificial rumen system by measuring the production of gas and short chain fatty acids. Inocula were obtained from the rumens of (1) four wild deer on a natural winter browse diet, (2) one captive deer fed a starvation diet of sagebrush, (3) a cow on a hay diet, (4) the same cow on hay and concentrate, and (5) two sheep on hay and concentrate. Production of short chain fatty acids by the inoculum of the deer fed sagebrush was significantly lower than that from all other animals. Except for appreciably smaller percentages of butyrate and iso-valerate plus valerate by the inoculum of the deer fed sagebrush, the composition of short chain fatty acids produced was very similar among all inoculum sources. Production of gas by the inoculum of the deer fed sagebrush was significantly less than that from all other animals. Inocula from the sheep and the cow fed concentrate and hay produced more gas, and those from the deer on browse and the cow on hay produced similar but progressively larger amounts. These results indicate that normal wild deer, like domestic ruminants, have a microflora capable of digesting hay and converting it to volatile fatty acids. However, by the time that starving deer arrive at a hay supply, the rumen microorganisms may be completely dead or contain low energy

Effects of Cellulose Levels on the Apparent Digestibility of Feeds Eaten by Mule Deer

Three artificial diets that varied in cellulose content but were similar in protein and energy levels were fed to three mule deer according to a latin square design. Food intake for each deer, on each diet, during each feeding period was similar. Energy and dry matter digestion varied between diets (P < 0.05) and both digestible energy and digestible dry matter were inversely related to dietary cellulose content. Cellulose digestion was somewhat variable between animals, feeds, and feeding trial periods. Protein digestion was similar in all feeding trials but crude fat digestion was somewhat greater on the low-cellulose diet. Limited cellulose digestion occurs in mule deer and affects energy and dry matter digestion of foodstuffs. The proximate analysis of important species of deer browse has many times been shown to have little value in predicting how a deer digests a particular forage item. Digestion trials with wild forages have been performed many times with deer of the genus Odocoileus. These investigations have shown differences in the value of par- ticular forages to deer and have compared the manner in which domestic and wild ruminants utilize the same forage. A diges- tion trial using wild forages and deer is seriously limited when the food presented to the deer has been selected by the investi- gator rather than by the animal. Sometimes this selected forage has been extensively modified by air drying, grinding, pelleting, or other treatment so that the foodstuff may bear little resemblance to the growing plant. Information about the comparative digestibility of the ration must then be analyzed with the realization that some circumstances were artificial. Important generalities describing how deer utilize foodstuffs should therefore be cross-checked with experiments that remove as many var- iables as possible from the digestion trials. Artificially compounded rations in which the variable components are reduced to only one may be used to allow a more rigorous statistical and biological analysis. This is a popular technique for examining, among other things, a general relationship between the level of a particular dietary constituent within a feed and the digest- ibility of that feed. Digestion trials with mule deer (0. hem- ionus) and feeds compounded from native browse plants demonstrated (Short and Remmenga 1965) a significant relationship between the cellulose content and the digestible energy of the feed. These find-

Use of Fecal Cellulose to Estimate Plant Tissue Eaten by Deer

Feeding trials conducted in 1962, with native browses, indicated relations between feed and fecal dry matter, lignin and cellulose. Prediction equations describing these relations are listed. Two range studies are described that indicated the feasibility of using fecal cellulose content to estimate plant tissue eaten by deer. (auth)