Jordan C. Pederson

In vitro digestibility among accessions of big sagebrush by wild mule deer and its relationship to monoterpenoid content.

Results of in vitro digestibility trials indicate that big sagebrush (Artemisia tridentata) is a highly digestible browse for wintering mule deer. Subspecies tridentata (62.lYo digested dry matter) was more highly digested than subspecies vaseyana (53.2% digested dry matter) and subspecies wyomingensis (51.4% digested dry matter). On an accession level, some accessions of big sagebrush were more highly digested than others. The accessional range was from 44.6% digested dry matter to 64.8%. No relationship was found between total monoterpenoids (essential or volatile oils) content and digestibility.

Does summer range quality influence sex ratios among mule deer fawns in Utah

Larger ratios of males to females were found among fawns from herd units where forage production on the summer ranges was low and the forage base was dominated by browse. Summer ranges where forage production was high and domhted by forbs produced even or female dominated sex ratios. The number of deer harvested per unit area was correlated with sex ratio of the fawn crop: harvests were lower where males were significantly overrep resented in the fawn crop and higher where sex ratios were even or female biased. We previously reported the comparative productivity of mule deer on 2 southeastern Utah mountains that differed markedly in summer range condition but had winter ranges of comparable quality (Pederson and Harper 1978, 1979). The La Sal Mountain mule deer herd was shown to consistently produce about 40% more fawns per doe than the Henry Mountain herd. Deer from the La Sals were also larger than animals of the same age and sex from the Henrys (Pederson and Harper 1978). We could detect no difference in either disease incidence or predation between the 2 herds, but the La Sal Mountain summer range was in good to excellent condition, and the forage base for deer was dominated by forbs. In contrast, the Henry Mountains summer range was in poor to fair condition, and the forage base was heavily dominated by shrubs (Pederson and Harper 1978). Since considerable evidence suggests that nutrition may influence the sex ratio of offspring born to a variety of cervid (deer) species (Julander et al. 1961; Verme 1965, 1967, 1969; Bannikov 1967; Robinette et al. 1973, 1977; McCullough 1979), we expanded our previous study to include a comparison of sex ratios in mule deer herds on 7 ranges known to vary among themselves in respect to vegetative condition. Sex ratio statistics have many implications for management. Medin and Anderson (1979) found that a 4% shift toward females in the ratio resulted in a 16% increase in fawn production. If range condition can be shown to be correlated with herd sex ratios, managers may be able to manipulate sex ratios through management of the forage base. Managers may also be better able to anticipate herd growth potential and prescribe more suitable management and harvest programs through a knowledge of range conditions coupled with inexpensive demographic studies.

Effects of monoterpenoid exposure on ability of rumen inocula to digest a set of forages.

Nagy et al. (1964) using in vitro techniques found that the monoterpenoids (essential or volatile oils) of big sagebrush (Artemisia tridentata) suppressed the growth of mule deer rumen microorganisms, decreased the rate of cellulose digestion and the production of gas and volatile fatty acids by the microorganisms. Oh et al. (I 967, 1968) found that the monoterpenoid hydrocarbons (the monoterpenes) of Douglas-fir needles actually enhanced in vitro microbial fermentation in sheep and deer inoculum. Sesquiterpenes were also found to be stimulatory. Microbial fermentation, however, was suppressed in the presence of the oxygenated monoterpenoids (alcohols, esters, aldehydes) of Douglas-fir (Oh et al. 1967, 1968; Longhurst et al. 1969). After a review of the literature, Welch and McArthur (1979) concluded that the results of in vitro and in vivo digestibility trials of big sagebrush did not support the contention that monoterpenoids suppressed digestion in mule deer. It was suggested by Nagy et al. (1964), Welch and McArthur (1979), and Van Soest (1981) that microorganisms in the rumen may be able to adapt to big sagebrush monoterpenoids. Observations made by Oh et al. (1967) support the adaptation idea. They found that citonellal (aldehyde), an oxygenated monoterpenoid, inhibited rumen microorganisms from sheep and deer that had no access to Douglas-fir needles (a monoterpenoid source), but produced no effect upon rumen microorganisms from deer that had access to Douglas-fir. Rumen inoculum collected from wild mule deer on summer, fall, winter, and spring ranges in central Utah was equally effective in If adaptation is important, the inoculum with unadapted rumen digesting alfalfa hay, orchardgrass hay, big sagebrush, curlleaf microorganisms should digest big sagebrush forage less readily mahogany, antelope bitterbrush, and hips of sweetbrier rose. than inoculum with adapted microorganisms. Therefore, we undertook this study to test the hypothesis that rumen inoculum Alfalfa hay was the forage most easily digested. Inocula from deer that had not been exposed to big sagebrush and juniper monotercollected from mule deer not consuming big sagebrush (summer penoids (essential oils) digested all test forages, including big sagerange) would digest significantly less dry matter of winter samples of big sagebrush forage than inoculum collected from mule deer brush equally as well as inoculum from deer that had been exposed consuming big sagebrush (winter range). to big sagebrush monoterpenoids. We concluded that rumen microorganisms do not have to adjust to the presence of the Materials and Methods monoterpenoids or other dietary changes. During 1979-1980, we collected rumen inoculum from 13 wild mule deer at seven points in time: July 18, September 7, October 29, December 3, January 14, February 25, and April 17. Two mule deer were sacrificed for each time period, with the exception of October 29 when one deer was taken. Deer were obtained from native ranges in central Utah. The method we used to collect rumen inoculum was described by Nagy et al. (1964). The collections of rumen inocula were tested against four native forages and two dry roughages collected from one site in central Utah and at one point in time. Native forages included the current year’s growth of big sagebrush, curlleaf mahogany (Cercocarpus ledifolius), antelope bitterbrush (Purshia tridentata), and the hips from sweetbrier rose (Rosa eglanteria). These forages were collected during midwinter and ground with a motorized steel mortar and pestle to a fine powder in liquid nitrogen (Welch and Pederson 1982). During the early spring of 1979, samples of alfalfa (Medicage sativa) and orchardgrass (Dactylis glomerata) were collected, dried, and ground in a Wiley mill (1 mm). All forages were stored in a freezer (-35” C). Welch and Pederson (1982) through in vitro means, found big sagebrush to be a highly digestible browse for wintering mule deer. They collected rumen inoculum from wild mule deer that had been feeding on big sagebrush for about 3 weeks. This was to ensure that the rumen microorganisms had fully adapted to the presence of big sagebrush monoterpenoids. Although that study (Welch and Pederson 1982) demonstrated that rumen inoculum readily digested big sagebrush, it did not furnish evidence concerning the ability of rumen microorganisms to adapt to the presence of monoterpenoids. We used the in vitro digestion procedure outlined by Pearson ( 1970), except that 1 .O g of fresh tissue was used for the four native forages. The dry matter content was determined for all forage samples digested. Rumen inoculum for each deer was tested separately. Burbank et al. (1979) reported that the pH of the bufferrumen inoculum can significantly affect the digestive ability of the inoculum. We found that the pH of the rumen fluid collected from the 13 deer varied from 6.5 to 6.8, therefore, the pH of the bufferrumen inoculum was adjusted to a pH of 6.8. Data were expressed as percent of digestible dry matter. Percentages were transformed (arcsin) for statistical analysis. Analysis of variance for a completely randomized design was used to evaluate differences in treatment effects. Treatment effects were measured by the ability of the various inoculum sources to digest each forage. Hartley’s range test was used to compare inoculum collection dates-the treatment means (Snedecor and Cochran 1967). Authors are regional game manager, Utah State Division of Wildlife Resources, Rumen contents of all 13 deer were saved to determine the Springville, 84663; principal research plant physiologist, Intermountain Forest and amount of big sagebrush and Utah juniper (Juniperus osteosRange Exp. Sta., Shrub Sciences, Laboratory, Provo, Utah 84601. The authors extend thanks to the Utah Division of Wildlife Resources personnel perma) in the diet (Cluff et al. 1982). who gave so freely of their time and talent: Harold Blackburn, Kevin Cherry, Dale Gurley, Norman Hancock, Robert Hasenyager, Rodney John, Leonard Newlin, and Results Ken Tuttle.. Manuscrrpt received January 7, 198 I. Amount of big sagebrush and juniper in the diet of the mule deer JOURNAL OF RANGE MANAGEMENT 35(4), July 1982 Table 1. Percent of big sagebrush and juniper in the diets of wild mule deer collected during 1979-1980. Two deer per date, except for October.

Monoterpenoid content of sage grouse ingesta.

We tested the hypothesis that the monoterpenoid levels in the ingesta from various digestive organs of sage grouse are less than that expected from the big sagebrush leaves ingested. Results supported the hypothesis. Dramatic reductions occurred between the gizzard and duodenum. Monoterpenoid levels in the ceca were nil; thus adverse effects of monoterpenoids on ceca microbes would also be nil.

Comparison of Ponderosa pines as feed and nonfeed trees for Abert squirrels

Twigs from five ponderosa pine trees (Pinus ponderosa) used by Abert squirrels (Sciurus aberti) as feed trees and five nonfeed trees were collected every 45 days and their monoterpenoid and nutrient content determined. Thet tests (unpaired observations) detected no significant difference in the level of monoterpenoids in the outer bark of feed (0.77%) and nonfeed (0.75%) trees. The same was true for inner bark of feed (0.10%) and nonfeed (0.16%) trees. Monoterpenoid levels in outer bark (0.75%) were significantly higher than inner bark (0.13%). The inner bark is what is eaten by Abert squirrels. Protein and other nutrients did not differ significantly between feed and nonfeed trees. However, both outer and inner bark were easier to remove from the woody portion of the feed tree twigs than those twigs collected from nonfeed trees. Therefore, due to the lack of differences in monoterpenoid and nutrient content between feed and nonfeed trees, we attributed the use of certain trees for use as feed trees to the ease of peeling and separating outer from inner bark.

Prevalence and Distribution of Elaeophora schneideri Wehr and Dikmans, 1935 in Mule Deer in Utah

The arterial worm Elaeophora schneiden Wehr and Dikmans 1935, was first recovered from domestic sheep in 1933 from Catron County, New Mexico (Kemper, 1938, N. Am. Vet. 19: 36-41), and was recovered from mule deer (Odocoileus h. hemionus (Rafinesque)) of Beaver County, Utah in 1933 by Wehr and Dikmans (1935, Zool. Anz. 110: 202-208). Since that time it has been observed in white-tailed deer (0. virginianus (Zimmermann)) and black-tailed deer (0. hemionus columbianus (Richardson)) in western Canada, and in western and southeastern United States (Davies, 1979, The ecology of Elaeophora schneideri in Vermego Park, New Mexico, Ph.D. Diss., Cob. St. Univ., Ft. Collins, Colorado, 236 pp.). It has been observed also in moose (Alces alces (L.)) (Worley and Greer, 1972, J. Wildl. Dis. 8: 242-244; Jensen et al., 1982a, Great Basin Nat. 42: 351-352), and Rocky Mountain elk (Cervus elaphus nelsoni (Bailey)) (Davies, 1979, op. cit.). The normal definitive hosts of this nematode are mule deer (Hibler and Adcock, 1971, In Parasitic Diseases of Wild Mammals, Davis and Anderson (eds.), Iowa State Univ. Press, Ames, Iowa, pp. 263-278) and white-tailed deer (Titche, 1976, Experimental infection of white-tailed deer with Elaeophora schneideri, MS. Thesis, Cob. St. Univ., Ft. Collins, Colorado, 69 pp.). When E. schneideri is found in these animals lesions are rarely observed. Infected