Blood characteristics of free-ranging white-tailed deer in southern Texas

Blood analytes of clinically normal and diseased neonatal and weaned farmed white-tailed deer (Odocoileus virginianus) fawns

Recent research focused on farmed deer has exposed many knowledge gaps regarding health assessment protocols for white-tailed deer (WTD). The objectives of this study were to establish de novo blood analyte reference intervals for farmed WTD fawns at birth (1-2 days of age; n = 84) and again at weaning (76-125 days of age; n = 28), to compare data at birth and at weaning to understand how these analytes are affected by the intrinsic factors age and sex in clinically normal WTD fawns, and to compare between clinically normal and sick WTD weanlings (respiratory disease n = 12; orbivirus-infected n = 6). Reference intervals were established for WTD fawns at birth and weaning. Female WTD neonates had significantly higher red blood cell counts, hematocrit, and hemoglobin compared to males. Most blood analytes were significantly different in clinically normal WTD neonates compared to weanlings, suggesting an effect of age. The observed sex- and age-related variations in WTD highlight the need to establish reference intervals that account for intrinsic factors. The comparison of clinically normal and sick WTD weanlings in this study identified higher MCHC and absolute monocytes in sick weanlings but these findings were presumably not biologically relevant given the small sample size for sick fawns. While the reference interval data presented herein will be useful for the veterinary care of WTD fawns at critical time periods in a high-density farm setting, this study also demonstrates the need to identify more sensitive and specific biomarkers for the assessment of health status in farmed WTD with specific underlying diseases.

Immune function and hematology of male cotton rats (Sigmodon hispidus) in response to food supplementation and methionine

We examined effects of supplementation of food quantity and quality (=enhanced methionine) on hematologic and immunologic parameters of wild, but enclosed, adult male cotton rats (Sigmodon hispidus) in north-central Oklahoma. Sheet metal enclosures were stocked with a high density of wild-caught cotton rats (160 animals/ha) and randomly assigned a treatment of no supplementation, mixed-ration supplementation or methionine-enhanced supplementation. Aside from small increases in counts of red blood cells and hematocrit levels, most indices of erythrocytic characteristics were not affected by supplementation with the mixed-ration or enhanced methionine. In contrast, platelet counts were highest in mixed-ration and methionine treatments and counts of total white blood cells were highest with methionine supplementation, albeit relative proportions of different leukocytes did not differ among treatments. Immunologically, neither delayed-type hypersensitivity response nor hemolytic-complement activity differed among treatments. Supplementation of food quantity and quality did not broadly affect hematologic parameters and immune function of male cotton rats, but enhanced platelet and leukocyte counts may confer advantages to overall health. Clarification of the role of such effects on population limitation or regulation requires additional research.

Physiological responses of neonatal white-tailed deer reflective of maternal dietary protein intake

Previously, we observed a strong correlation between immunity parameters of neonatal white-tailed deer (Odocoileus virginianus) fawns and probability of survival in an overpopulated herd. As a result, we monitored age-related changes in neonatal fawn physiology, with an emphasis on measures of passive immune transfer, to test the hypothesis that maternal protein malnutrition adversely influences the vigor and immunocompetence of newborn fawns. Body mass and physiological data were collected from 55 neonatal fawns (1–28 days old) born to captive does on either a high-protein (16%) or low-protein (6.5%) diet during the latter half of gestation through lactation (15 March – 1 September). The study was conducted over two breeding seasons (1992 and 1993), with does receiving the same diet the second year to assess diet × year interactions. We found little evidence of compromised immunocompetence of neonatal fawns born to protein-malnourished does in either year. The absence of any sign of suppressed in utero development suggested that the nutritional deficiencies of the diet regime we used may not have been chronic enough to mirror conditions that exist in the wild. Birth mass, hematology, and serum chemistries of fawns suggested that low-protein diets caused reductions in maternal nutritional status by the second year. The results of this study and those of preliminary field observations suggested that compromised immunocompetence of neonatal fawns may be manifested only during chronic malnutrition, when the protein reserves of does become depleted or insufficient.