Descriptive aspects of two fawn populations as delineated by reproductive differences
Urbston, David F.
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Prior to 1971, doe fawns from a river swamp portion of the Energy Research Development Agency's Savannah River Plant near Aiken, South Carolina, bred at significantly lower rates than did fawns from a proximal upland habitat. During the fall and early winter of 1971, nutritional, stress, genetic, and pathological aspects of male and female fawns from these habitats were evaluated in an attempt to delineate possible factors affecting their past reproductive performance. Kidney fat index was correlated with percent body fat as determined by whole body analysis. Although KFI was not significantly different between sexes or areas, swamp fawns had significantly more body fat than did individuals from the uplands. No differences in growth rates between individuals from both areas were detected. Upland fawns contained significantly more body magnesium than did swamp individuals. Although calcium, nitrogen, manganese, and phosphorus values were similar between the 2 areas, seasonal and sex differences were observed. Rumen protein was significantly greater in upland fawns; crude protein levels from swamp rumina were marginal for optimum growth and development. Swamp rumina contained significantly more acorns than did those from the uplands. However, significantly greater amounts of honeysuckle were observed in upland rumina, and species diversity was greater. Adrenal weights were similar between the 2 areas and both sexes. Larger animals had heavier adrenal glands. Several animals judged to be in poor condition had adrenal weights within the range of those which appeared to be in excellent physical condition. Increased levels of vanilmandelic acid were indicative of increased stress levels. Although the technique was not applicable to blood, increased urinary levels of the catecholamine were observed in confined deer and those run by dogs. Significant differences between areas and sexes were not detected. Older animals had significantly greater VMA levels than younger individuals. Ninety-eight fawns and 114 older deer were evaluated for genetic heterozygosity by electrophoretic analysis of 22 proteins. Average heterozygosity for all deer was 12. 7 percent. No significant differences in average heterozygosity between fawns or yearlings of the 2 areas was observed, but upland adult females were significantly more heterozygous than adult swamp females. Changes occurred in average heterozygosity in swamp females during 1970 and 1971; fawns and yearlings were significantly more heterozygous than adult deer. Significant relationships were observed between VMA level, mineral content, and sex for several loci. Brucellosis and leptospirosis were not significant factors in either population. Neither follicle sizes nor ovulation rates were significantly different between doe fawns of the 2 habitats. Onset and development of spermatogenesis was similar in males of the 2 habitats, although individuals from the swamp had significantly greater testes weights in relation to body sizes. Reproductive rates were evaluated during the period 1971 through 1973; no significant differences between the 2 populations were observed. It was concluded that factors which inhibited doe fawn breeding in the swamp prior to 1971 were high animal density, fluctuating mast crops, and low protein availability. By 1971, animal density in the swamp had been reduced to the extent that these were no longer factors.
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