Regulatory aspects of fluoride toxicity.

The polybrominated biphenyl (PBB) contamination incident that occurred in Michigan from 1973 to 1978 brought about an acute consciousness of dairy herd health. At the insistence of owners with assumed low level PBB health complaints and problems, an intensive examination was made of their herds. One of the distinct problems emerging from these team investigations was chronic fluorosis. The discovery of this problem led to state regulations limiting fluorine contentin feeds. The resulting restrictions on this element in Michigan are the most stringent in the United States.

Ectopic fetuses in two cottontail rabbits.

Mummified fetuses were discovered in the abdominal cavities of two cottontail rabbits (Sylvilagus floridanus) collected during separate years from the same geographical location in Virginia. One of these rabbits had a patent opening through the vaginal wall to the abdominal cavity. The uterus and vagina of the second rabbit appeared normal.

A modified blow-gun syringe for remote injection of captive wildlife.

A modified syringe capable of automatic injection and suitable for use with a blow-gun is described. The syringe has been used successfully with white-tailed deer (Odocoileus virginianus) under confined conditions. Desirable characteristics for blow-gun syringes are discussed.

Hematologic comparisons of shot and live trapped cottontail rabbits.

Comparisons were made between hematologic measurements of shot and box-trapped cottontail rabbits (Sylvilagus floridanus). Trapped rabbits had significantly (P less than 0.001) higher serum corticoid levels and segmented neutrophil percentages and significantly (P less than 0.001) lower lymphocyte percentages than did shot rabbits. Trapped rabbits also had significantly (P less than 0.05) higher packed cell volumes and blood urea nitrogen values than did shot rabbits.

Effects of a polychlorinated biphenyl (PCB) on sleeping times, plasma corticosteroids, and testicular activity of white-footed mice.

Forty adult male white-footed mice (Peromyscus leucopus) were divided into four equal groups and fed diets containing 0, 100, 200 or 400 p.p.m. of a polychlorinated biphenyl (PCB) for 2 weeks. PCB ingestion increased liver weights and reduced pentobarbital-induced sleeping times at all levels tested, indicating increased hepatic microsomal enzyme activity. Plasma corticoid levels, seminal vesicle weights and testicular spermatozoa numbers were reduced at the 400 p.p.m. level.

Bioavailability of lead from contaminated sediment in northern bobwhites, Colinus virginianus.

Sediment from Killarney Lake, Idaho was added to the diet of captive northern bobwhites (Colinus virginianus) to determine absorption of Pb from contaminated sediment. The sediment, containing 4,500 micrograms g-1 Pb dry weight (d.w.), was added to ground poultry ration at 8% dry matter intake (DMI) for 21 days. Concentrations of Pb in blood, liver, and kidneys of each bobwhite were determined and compared to concentrations in untreated control bobwhites. Treated bobwhites showed no significant decline (P > 0.05) in food intake or body mass over time. In 90% of treated bobwhites, blood Pb concentrations reached levels associated with clinical Pb poisoning (> 0.8 microgram g-1 wet weight, w.w.); and all treated bobwhites had elevated liver and kidney Pb concentrations. It was shown that tissue Pb accumulation can occur from ingestion of Pb-contaminated sediment.

Effect of tannins on galliform cecal partitioning.

Winter diets of ruffed grouse (Bonasa umbellus) and other galliformes are high in tannins. We fed quebracho, a condensed tannin, to ruffed grouse and found no effect on dry matter intake or body mass at levels up to 6% of the diet. However, a high-fiber diet with 8% quebracho resulted in reduced dry matter intake and body mass loss. Grouse could not tolerate a diet with 8% tannic acid, a hydrolyzable tannin, which caused a large reduction in dry matter intake and body mass. Northern bobwhite (Colinus virginianus) and ruffed grouse responded to dietary quebracho tannin by increasing the proportion of digesta that was excreted from the ceca. In the northern bobwhite, 59%-76% of the tannin recovered from the feces was in cecal feces. There was no difference in average passage rates of liquid and fiber digesta, although variation was high in tannin-fed birds. The role of the ceca in handling tannin requires further investigation.

Effects of tannins on digestion and detoxification activity in gray squirrels (Sciurus carolinensis).

Acorn tannins may affect food preferences and foraging strategies of squirrels through effects on acorn palatability and digestibility and squirrel physiology. Captive eastern gray squirrels (Sciurus carolinensis) were fed 100% red oak (Quercus rubra) or white oak (Quercus alba) acorn diets to determine effects on intake, digestion, and detoxification activity. Red oak acorns had higher phenol and tannin levels, which may explain the lower dry matter intakes and apparent protein digestibilities and the higher glucuronidation activities observed in squirrels. Although the white oak acorn diet had lower apparent protein digestibilities than the reference diet, it did not suppress dry matter intake for a prolonged period or stimulate glucuronidation. Negative physiological effects of a 100% red oak acorn diet suggest gray squirrels may require other foods to dilute tannin intake and provide additional nutrients. To distinguish the roles of different tannin types in the observed effects of acorn diets on squirrels, squirrels were fed rat chow containing no tannins, 4% or 8% tannic acid (hydrolyzable tannin), or 3% or 6% quebracho (condensed tannin). Apparent protein digestibilities were reduced by tannic acid and quebracho diets. Only the 8% tannic acid diet tended to increase glucuronidation. Specific effects of tannins may largely depend on tannin type, composition, and source and on other nutritional and physiological factors.

Muskrat populations in Virginia's Elizabeth River: physiological condition and accumulation of environmental contaminants.

This study evaluated the physiological condition and environmental contaminant concentrations in muskrats inhabiting the contaminated lower region of the Elizabeth River, Virginia, (USA). Muskrats trapped in the lower region of the Elizabeth River weighed less, had lower mean fat indexes, lower relative spleen weights, greater relative adrenal weights, and an increased incidence of disease and parasitism compared to muskrats trapped in the less contaminated upper region of the Elizabeth River or Nansemond River. Concentrations of the metals aluminum, cadmium, copper, nickel, and zinc and the number of polyaromatic hydrocarbon compounds were greater in lower Elizabeth River muskrats compared to upper region Elizabeth River or Nansemond River muskrats. These physiological data indicated that muskrats in the lower region of the Elizabeth River were in poor health relative to muskrats from the other regions studied. However, no significant difference in fecundity or density was observed among regions studied, suggesting that the level of environmental contaminant exposure was not sufficient to elicit a population level response. Greater population declines following severe natural environmental stresses (large storms, extreme cold, etc.) would be anticipated in lower region Elizabeth River muskrats; however, the muskrat population in this region does not now appear to be at risk of extirpation.