Larry W. Varner

Nitrogen requirements for antler growth and maintenance in white-tailed deer

Data describing nitrogen (N) requirements for maintenance and production in adult male cervids are limited. We used balance trials (n = 72) and regression analysis to estimate N requirements for maintenance and production (i.e., antler development) in adult (>2-yr-old) white-tailed deer (Odocoileus virginianus). Nitrogen deposition in antlers was estimated and included in balance calculations. Minimal maintenance and average growth requirements (± 2 SE) for N during the antler growth period (Apr-Aug) were 0.61 (± 0.16) and 1.06 (± 0.15)g g N/kg 0.75 /day, respectively. At intake rates observed in this study, these requirements are equivalent to crude protein requirements of 5.8 and 9.9% for maintenance and growth, respectively. Minimal maintenance and average growth requirements for N during winter (Oct-Feb) were 0.37 (±0.33) and 0.92 (± 0.30) g N/kg 0.75 /day, respectively. At intake rates observed in this study, these requirements are equivalent to crude protein requirements of 4.1 and 10.1% for maintenance and growth, respectively. We discuss shortcomings of balance trials to measure N requirements, such as the need to quantify all sources of N loss.

Macro and trace mineral content of selected south Texas deer forages.

White-tailed deer (Odocoileus virginianus) derive the majority of their dietary mineral intake from range forages which may be deficient in one or more essential minerals. We have described the macro and trace mineral concentration of 18 shrub, 26 forb, 7 grass, and 1 cactus species, known to occur in south Texas deer diets, collected from the Chaparral Wildlife Management Area in 1974 and 1975. Within each forage class, there were no seasonal differences in calcium (Ca), sodium (Na), potassium (K), or magnesium (Mg) concentrations. Phosphorus (P) concentrations in browse were higher (PI0 051 durinn the snrinn (0.20%) thnn dur_~ _~~~~ _ __e__, ______ _ _..-=_____ \_ .__, “, ----__ -ing other seasons(O.U-0.16%). Forb P concentrations were greatest during the spring and winter periods (0.26 and 0.2970, respectively), and P levels in grasses (0.24-0.14%) decreased as the forage matured and reached senescence. Shrubs contained less P and K (p10.01) than either grasses or forbs; whereas, grasses contained lower concentrations of Ca and Mg (EO.01) than shrubs or forbs. Sodium concentrations did not diier among forage classes. Forbs contained greater (fiO.01) levels of copper (Cu) and zinc (Zn) than erasses or browsennd hr~wm c~n!ri~ed 1~9s ire” (Fe! m-----I ---(%0.01) than forbs or grasses. Manganese concentrations did not differ among forage classes. There were differences in mineral concentrations among species within forage class. Results suggest concentrations of all minerals except P met or exceeded minimum domestic animal requirements. Managers should provide a diversity of plant species and encourage practices that promote forb growth to provide optimum and nutritional benefits for deer.

Nutrition of the collared peccary in south Texas

Effects of growth, reproduction, sex, age, season, and diet quality on collared peccary (Tayassu tajacu) digestion and assimilation efficiencies, and on nutrient requirements of peccaries in south Texas are presented. Five metabolism trials were conducted with 10 collared peccaries fed either a concentrate diet or a forage diet representing the seasonal diet of free-living peccaries. Dry matter digestibility ranged from 49-72% for natural diets and was 84% for concentrate. Mean true digestibilities for energy, nitrogen, and phosphorus were 68, 46, and 70%, respectively, for natural diets and 89, 81, and 87%, respectively, for concentrate. Digestibility of the diet was directly related to nitrogen in the diet and the age of the animal and inversely related to consumption, gross energy, phosphorus, fiber, and ash in the diet. Mean true assimilation efficiencies for energy, nitrogen, and phosphorus were 64, 31, and 84%, respectively, for natural diets and 86, 58, and 84%, respectively, for concentrate. Maintenance requirements for adult, nonreproductive animals were 148.5 kcal/kg MBW/day of digestible energy (136.9 kcal/kg MBW/day of assimilated energy), 0.837 g/kg MBW/day of digestible nitrogen, and 0.844 g/kg MBW/day of digestible phosphorus. Daily energy requirements were directly related to growth and reproductive activity (increasing with duration of pregnancy and lactation) and inversely related to ambient temperature and age of animal. J. WILDL. MANAGE. 48(3):749-761 Information concerning the nutrient requirements of collared peccaries in Texas is sparse. Lindheimer pricklypear (Opuntia lindheimeri) is common in the diet (Jennings and Harris 1953), but the proportion in the diet varies seasonally (Low 1970, Everitt et al. 1981). Although digestibility of pricklypear for peccaries has been reported as 80% (Zervanos 1972, Shively 1979), the seasonal variation in diet digestibility is unknown. Zervanos (1972) determined that an average peccary in Arizona required 104 kcal/kg MBW/day in winter and 90 kcal/ kg MBW/day in summer. Similar estimates for peccaries in south Texas are not available. Information concerning the effects of physiological status of the animal and diet quality on consumption also is lacking. This paper describes and quantifies effects of growth, reproduction, sex, age, season, and diet quality on peccary digestion and assimilation efficiencies and on n trient requirements in south Texas. Support and funding for this research were provided by the Caesar Kleberg Res. Program in Wildl. Ecol., Dep. of Wildl. and Fish. Sci., Tex. A&M Univ. We thank t e staff of the Tex. Agric. Exp. Stn. at Uvalde for their assistance during this study, particularly L. H. Blankenship for advice on handling the animals. We also acknowledge the assistance of the staff of the Chaparosa Ranch, particularly P. O. Reardon, and the personnel of the Chaparral Wildl. Manage. Area, particularly C. E. Davis, for their cooperation and advice.

Digestibility of guajillo for white-tailed deer.

A study was conducted from May 1986 to June 1987 with white-tailed deer (Odocoileus virginianus) to determine seasonal nutritive value and nutrient digestibilities of guajillo (Acacia berlandieri) and a pelleted diet. In vivo dry matter digestibility (DMD) of guajillo varied seasonally from 35.2 to 48.1% and was inversely correlated to levels of condensed tannins in the forage. Apparent protein digestibility varied seasonally from 13.7 to 45.8% and was a highly dependent function R2 = 0.97) of the amount of neutral detergent fiber nitrogen (NDFN) digested and the negative impact of condensed tannins. Cellulose and hemicellulose digestibilities also varied seasonally (0.6 to 13.5% and 52.3 to 71.1%, respectively). Nutrient digestibilities of the pelleted diet did not vary by season, sex, or age. Dry matter digestibility of the pelleted diet was 75.6% +/- 0.9 and true protein digestibility was 95.0 +/- 0.04. Results suggest summer is a stressful period for south Texas deer due to low protein and energy digestibility and high levels of condensed tannins.

Effects of seasonal protein restriction on antlerogenesis and body mass in adult male white-tailed deer

Seasonal dynamics in protein availability vary with latitude throughout the geographic range of white-tailed deer (Odocoileus virginianus), but the effects of variability in the timing of protein availability on deer performance or antlerogenesis are understood poorly. We designed an experiment to examine the effects of a 12-week (spring or summer) protein restriction on deer performance. Eighteen male white-tailed deer (≥2 yr old) were blocked by past antler size, body mass, and age, then randomly assigned to one of 3 diet groups (LH, HL, HH) composed of 2 dietary levels of crude protein (CP), low (L, 7%) or high (H, 16%) during 1992-93. The HH group served as the control, receiving a high protein diet during the antlerogenic period (Mar-Aug) of each year. The LH and HL groups received a low protein diet for a 12-week period in spring (LH) or summer (HL) and a high protein diet in the opposite season. During fall and winter, all deer consumed a medium protein diet created by mixing the experimental diets. Body mass, feed intake, antler characteristics, and serum chemistries were examined. No diet effects were found for any antler characteristic measured. Body mass varied by a diet-month interaction in 1992 (P = 0.04) and in 1993 (P = 0.01), because deer on H diets from June to September gained mass faster than deer on L diets for the same period. Rapid gain of body mass was accomplished by increased feed efficiency rather than increased feed intake. Final body mass did not vary by diet (P = 0.587). In general, serum chemistry levels were consistent with those reported in the literature. Adult white-tailed deer compensated for a 12-week protein restriction within a 5-17-week realimentation period. Greater treatment effects during the second year of the study suggested cumulative effects of protein restriction on deer performance.

Serum and urine biochemical indicators of nutritional status in adult female collared peccaries, Tayassu tajacu (Tayassuidae)

Abstract 1. 1. Physiological responses of 13 adult female collared peccaries (Tayassu tajacu) to high quality and low quality diets, fed for 15 weeks, were examined. The low quality diet simulated energy and protein intake of peccaries during poor range conditions resulting from drought. Blood samples were collected after 10 and 15 weeks of dietary treatment; urine samples were collected after 15 weeks of treatment. 2. 2. Females receiving the low quality diet for 15 weeks lost 27.4% of their original body weight, compared to no weight change among high quality-fed females. 3. 3. Red blood cell counts, hematocrits, and hemoglobin concentrations were significantly greater among females fed a high quality diet compared to those receiving a low quality diet. High quality-fed females also had a higher mean corpuscular hemoglobin concentration. Plasma fibrinogen concentration was nearly twice as great among females receiving the low quality diet compared to the high quality group. 4. 4. Consumption of the low quality diet resulted in significantly elevated serum levels of nonesterified fatty acids, alkaline phosphatase, phosphorus, alpha-2 globulin and alpha globulin: beta globulin ratio. 5. 5. Consumption of the low quality diet resulted in significantly lowered serum levels of urea nitrogen, calcium, zinc, calcium: phosphorus, urea index, beta-1 flobulin, beta globulin: albumin ratio, thyroxine and triiodothyronine. 6. 6. Serum levels ofcreatinine, total bilirubin, glucose, cholesterol, gamma glutamyltransferase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, potassium, copper, magnesium, sodium chloride, total protein and gamma globulin were unaffected by diet quality. 7. 7. Urine chemistry results suggested pH, osmolarity, albumin, creatinine phosphokinase, calcium and phosphorus concentrations might be useful indices for assessing nutritional status in female peccaries.

Physiological responses of the adult male collared peccary, Tayassu tajacu (tayassuidae), to severe dietary restriction

Metabolic and hormonal responses of eight adult male collared peccaries (Tayassu tajacu) to an ad libitum diet intake, or 25% of an ad libitum intake, were examined. Blood samples for hematological, serum-biochemical and hormonal profiles were collected at three week intervals during the nine week experiment starting 4 August 1983. Males fed on the restricted diet lost an average of 26% of their body weight during the trial, compared to a slight weight gain for those fed ad libitum. Characteristics of the red and white blood cell populations were not influenced by diet intake, with the exception of mean corpuscular volume, which was consistently lower amongst males fed on the restricted diet. Restricted food intake resulted in significantly elevated serum values for urea nitrogen, urea nitrogen:creatinine, urea index, alpha globulin:beta globulin, gamma globulin:albumin, nonesterified fatty acids, alkaline phosphatase and lactate dehydrogenase isozymes (LD1 and LD2). Restricted food intake resulted in significantly lowered serum values for total alpha globulin, alpha-1 globulin, total beta globulin, beta-1 globulin, beta-2 globulin, glucose, triglycerides, calcium, magnesium, sodium, chloride, copper and triiodothyronine. Serum levels of creatinine, total protein, albumin, alpha-2 globulin, uric acid, total bilirubin, cholesterol, aspartate aminotransferase, alanine aminotransferase, gamma glutamyltransferase, lactate dehydrogenase, phosphorus, calcium:phosphorus, potassium, iron, zinc and thyroxine were unaffected by diet intake level. Semen evaluation indicated spermatogenesis was not affected by dietary restriction despite reductions in scrotal circumference and ejaculate gel volume. Serum testosterone levels were significantly lower among males fed on the restricted diet after nine weeks. These data suggest male libido might be depressed during poor range conditions, while maintenance of spermatogenesis might permit them to take immediate advantage of improved range conditions. Blood analysis of metabolic and hormonal function can provide useful information for predicting the adult males nutritional and reproductive condition.

Hematology of the Collared Peccary

The collared peccary (Tayassu tajacu) inhabits regions of the Southwest experiencing seasonal extremes in rainfall which influence the quantity and quality of available food. Seasonal adaptations of the peccary were studied by Zervanos and Hadley (1973). The peccary responds physiologically to environmental stress by lowered reproductive success (Low 1970, Bissonette 1982). If these and other adaptations also are reflected in certain hematological variables, such values may be useful in monitoring peccary-environment interactions, hence their physical condition. Baseline hematology values currently are available for three individual collared peccaries from zoos (Hawkey 1975, Schalm et al. 1975). Zervanos and Hadley (1973) noted seasonal variation in the mean hematocrit (%) values of five to nine peccaries on two diets and a dehydration regime. This paper presents 12 hematological values for captive and wild peccaries and examines the influence of season, sex, age, and nutritional change on the various parameters.

Indigestible Particulate Passage in White-Tailed Deer

Relationships among intake, digestion, and passage rates for white–tailed deer (Odocoileus virginianus) eating guajillo (Acacia berlandieri) were examined in a completely randomized balanced design metabolism experiment. Dry matter intake was positively correlated (P = 0.0005) with rate of indigestible particle disappearance from the rumen. The more highly digested diets had longer ruminal and total tract mean retention times (MRT). There were seasonal differences in ruminal and total tract MRT. Differences in total tract MRT were a function of ruminal turnover rates, not of time spent in the lower tract. No chemical or physical criteria were related directly to ruminal or total tract MRT. Dietary NDF concentrations varied seasonally, but permanganate lignin concentration was similar across seasons. Passage rates were not a function of permanganate lignin concentration; rather, low cell wall content of the forage allowed for rapid excretion of indigestible particles.

In vitro Digestability of Fall Forages by Coexisting Deer Species in Texas

Percent in vitro digestible dry matter (%DDM) of seven common fall forages was estimated using rumen inocula from three fallow deer (Dama dama), two sika deer (Cervus nippon), and two white-tailed deer (Odocoileus virginianus). Inocula were collected from animals sacrificed on 4 November 1987 on a ranch in Bandera County, in the Edwards Plateau Region of south-central Texas. Forage samples were collected during October 1987 in Bandera County and adjacent Kerr County. Estimates of %DDM were compared to determine if exotic falllow and sika deer are better able to digest common fall forages than native white-tailed deer. Sika deer inocula digested three of the seven forages better (P 0.05) in %DDM among deer species. These results support the hypothesis that sika deer are at a competitive advantage over white-tailed deer due to their ability to more completely digest common range forages.