H. H. Hayes

DIGESTIBILITY AND RELATED NUTRITIONAL DATA FOR SEVEN NORTHERN DEER BROWSE SPECIES

Energy use and related data are presented for seven northern winter foods of white-tailed deer (Odocoileus virginianus). Hemlock (Tsuga canadensis), balsam fir (Abies balsamea), red maple (Acer rubrum), striped maple (A. pensylvanicum), mountain maple (A. spicatum), hobblebush (Viburnum alnifolium), and hazelnut (Corylus cornuta) were fed in mixed rations to captive deer. Species tested had gross energy digestibilities ranging from 30 (red maple) to 54 percent (hobblebush). The amount of digestible, metabolizable, and net energy in each of the three maple species evaluated was very sim- ilar. Metabolizable energy ranged from 24 percent (1.2 kcal/g) for striped maple to 46 percent (2.2 kcal/g) for hobblebush. The lowest net energy was observed for striped maple (5 percent or 0.2 kcal/g), the highest for hobblebush (37 percent or 1.8 kcal/g). Crude protein was digested poorly in hemlock, balsam, and red maple (-5, 11, and 1 percent digestible, respectively) as compared with an average value of 47 percent for the remaining 4 species. The digestibilities of fat, fiber, and nitrogen-free extract of the seven plant species are presented and discussed. An example of the calculation of browse require- ment during a northern winter period, based on these and related data, is presented. J. WILDL. MANAGE. 40(4):630-638

Predicting Metabolic Rate from Telemetered Heart Rate in White-Tailed Deer

Six adult white-tailed deer (Odocoileus virginianus) were equipped with heart rate telemeters and placed in a temperature-controlled, indirect respiration calorimeter to measure heart rate and metabolic rate simultaneously. Over a 4-year period, from 1970 to 1973, 20 trials were conducted covering 9 calendar months. In each trial 5 to 12 different ambient temperatures were maintained, each for 12 consecutive hours (period), giving a wide range in the traits being measured; in all, 165 such periods were studied. An equation is presented for predicting metabolic rate from mean heart rate; it accounts for 78 percent of the variation in metabolic rate. Further application of this tool to improve our understanding of the relationship of deer to their environment is discussed. J. WILDL. MANAGE. 40(4):626-629 Work at our laboratory (Silver et al. 1969, Thompson et al. 1973) has revealed remarkable seasonal variability in maintenance net energy requirements (fasting metabolic rate) of fawns and adult deer. Numerous investigators (including Silver and Colovos 1957, Wood et al. 1962, Thompson et al. 1973) have noted cessation of growth (measured as maintenance or loss of body weight) during winter, although Thompson et al. found that body protein deposition continued in fawns despite negative energy balance, apparently caused by self-imposed restriction of feed intake. Therefore, a knowledge of the energy needed by deer for body maintenance, for use as a base line in estimating energy needed for various productive functions, could be helpful in their proper management. Even during winter, when deer often subsist on submaintenance diets, a knowledge of maintenance energy needs can serve as a reference for evaluating degree of undernutrition. To be able eventually to predict metabolic rate in deer not confined to a respiration calorimeter, Skutt et al. (1973) developed small, implantable transmitters to monitor heart rate and other physiological data, remotely, from unrestrained deer. The objective of this experiment was to develop an equation for predicting metabolic rate from mean heart rate. MATERIALS AND METHODS Six adult white-tailed deer, 3 does and 3 bucks, were used in 20 trials covering 9 different calendar months over a 4-year period (1970-73). Deer were reared in captivity (outdoor pens) and conditioned to the laboratory environment and to routine crating and transport. In each trial a series of 5 to 12 different ambient temperatures was maintained, each temperature for 12 consecutive hours (period), in a temperaturecontrolled, indirect respiration calorimeter; such periods also were consecutive within trials. Trials were summarized by seasons of the year, summer beginning 21 June. Because of the complexity of integrating animal availability, surgical and calorimetric procedures, and food intake with seasons, the schedule of experimentation led to imbalances in subclasses. Distribution of pe1 Published with the approval of the Director of the New Hampshire Agricultural Experiment Station as Scientific Contribution 696. Research partially supported by a contribution of P-R Proj. W-51-R, New Hampshire. 626 J. Wildl. Manage. 40(4):1976 This content downloaded from 207.46.13.127 on Wed, 28 Jun 2017 17:57:56 UTC All use subject to http://about.jstor.org/terms PREDICTING METABOLIC RATE IN DEER * Holter et al. 627 Table 1. Distribution of 10-hour periods (n = 165) among classes of main effects. Main effect No. 10-hour class periods

PROTEIN REQUIREMENT OF WHITE-TAILED DEER FAWNS'

Eight hand-reared white-tailed deer (Odocoileus virginianus) fawns were randomly paired and pairs were randomly assigned to 1 of 4 isocaloric diets containing 11, 15, 20, and 25 percent crude protein (dry matter basis) to study their protein requirement. Thirty-two complete digestibility, nitro- gen balance, and energy balance trials were carried out. Partition of dietary energy was not signifi- cantly affected by protein level in the diet, except that proportion of energy lost in urine, presumably ketones, increased significantly (P < 0.05) with increasing dietary crude protein. Apparent digestibility of protein increased significantly up to 20 percent ration crude protein, but most of this difference was attributable to decreasing proportion of metabolic nitrogen (0.37 g/100 g diet dry matter) in feces; proportion of ingested nitrogen lost in urine increased with increasing nitrogen intake. The fawns re- quirement for maximum growth (body retention of dietary protein), estimated by regression analysis, was 19 g digestible crude protein per kilogram of metabolic body weight (W075) daily. J. WILDL. MANAGE. 39(3):582-589 White-tailed deer, an aesthetically and economically valuable resource, are increas- ingly threatened by the effects of urban- ization in many areas. Their survival in optimum quantity and quality will depend largely on intensive management based on biologically sound principles. Deer man- agers will need information on the nutri- tional requirements of different age classes of deer throughout the year, and on the value of natural foods in meeting these re- quirements. Fawns probably are the age class most vulnerable to undernutrition during the winter. Certainly the food consumed dur- ing the preceding fall contributes greatly to winter survival. Thompson et al. (1973: 307) reported that the metabolizable energy required for maintenance of fawns is higher (38 percent, our calculation) during pe- riods of weight gain than in winter. They also found that the component of growth described by deposition of body protein may continue despite body weight loss and negative energy balance during the winter. Although energy generally is the most crit- ical factor in deer nutrition, the work of Murphy and Coates (1966) suggested that low protein content of foods may account for low productivity and suboptimum phys- ical development as in most other species.

Low-Power Implantable Transmitters for Telemetry of Heart Rate and Temperature from White-Tailed Deer

Low-power implantable transmitters have been developed for continuous telemetry of heart rate and temperature data from white-tailed deer (Odocoileus virginianus). Lifetimes of up to one year (limited by battery shelf life) are obtainable for temperature transmitters using newly developed, commercially available RCA COS/MOS digital integrated circuits. A reliable, easily constructed EKG transmitter also has been developed. Construction techniques are described which permit rugged, hermetic sealing of transmitter electronics. J. WILDL. MANAGE. 37(3):413-417 In order to study the effects of varying ambient temperatures on the reactions of wildlife to their year round environment, estimation of physiological parameters often is necessary. Even after repeated exposure and training, certain species, such as the white-tailed deer, assume abnormal physiological traits when they come into direct contact with humans. Therefore, remote monitoring of such traits as skin temperature, deep body temperature, and heart rate is essential when these traits are being studied. The objective of this paper is to describe the design, construction, and implantation of transmitters for use in the remote monitoring of body temperatures and heart rate in the white-tailed deer. MATERIALS AND METHODS

ESTIMATING METHANE, URINE, AND HEAT INCREMENT FOR DEER CONSUMING BROWSE'

For white-tailed deer (Odocoileus virginianus) consuming woody browse species, significant relationships (P < 0.05) were found to exist among daily energy losses in urine, methane, and heat in- crement and several of the more easily determined measures of the conventional digestion trial. Simple linear regression as well as multiple regression analyses indicated that urine and methane energy losses may both be accurately predicted from conventional digestibility data. The highest correlations were found between urine energy losses and the single variable, fat intake (r - 0.89), and a combination of seven variables (R = 0.98). These regressions had standard errors representing :?_ 14 and ? 9 percent of the estimated mean, respectively. The best fit between methane and a single variable was found with digestible nitrogen-free extract intake (r = 0.72), whereas methane regressed on a combination of five variables had a correlation coefficient of 0.82. Standard errors for these regressions were ? 19 and + 17 percent of the estimated mean, respectively. Several single variables were significantly (P < 0.05) correlated with heat increment, although the highest of these (digestible ether extract) had a correla- tion coefficient of only 0.40. The most highly correlated multiple regression with heat increment was obtained from six variables (R - 0.75). This regression had a SE of 113 or -+-32 percent of the esti- mated mean. Predictive equations are presented for simple linear and multiple regression information on each of the dependent variables.