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in Boise, ID. He earned a B.S. degree in forest management from Iowa State University in 1957, an M.S. degree in wildlife management from Colorado State University in 1959, and a Ph.D. degree in range ecosystems from Colorado State University in 1976. His research has included studies in mule deer ecology, big-game range improvement, mule deer population modeling, and nongame bird and small mammal ecology and habitat management. GORDON D. BOOTH is leader of the Statistics and Computer Sciences Group for the Intermountain Research Station in Ogden. UT. He received a B.A. degree in 1960 and a B.S. degree in statistics in 1963, both from Brigham Young University. Then he was granted an M.S. degree in 1967 and a Ph.D. degree in 1973, both in statistics and both from Iowa State University. From 1963 to 1965, he worked as consulting statistician with U.S. Steel Corporation and with Phillips Petroleum Co. From 1967 to 1981 he worked as consulting statistician with the Agricultural Research Service, U.S. Department of Agriculture. He has been in his present position since 1981.

Abstract. Coronavirus titers in small intestine, degree of villous atrophy and apparent rates of regeneration of intestinal villi were compared in newborn, 3-week-old and adult pigs for 1 week after they were exposed to the transmissible gastroenteritis virus of swine. The response within the newborn group was homogeneous, resulting in high virus titers, maximal villous atrophy and comparatively slow regeneration. In general, virus titers were lower, villous atrophy was less severe and regeneration more rapid in both older groups than in the newborn pigs. However, the response varied greatly in the older groups. The 3-week-old group was divided into two populations. The major population had low virus titers and developed partial villous atrophy, whereas the minor population had marked villous atrophy and virus titers comparable to those of the newborn pigs. These observations support the hypothesis that the accelerated replacement of villous epithelium in the small intestine of pigs during the first 3 weeks contributes to the innate age-dependent resistance to transmissible gastroenteritis. The accelerated replacement of villous epithelial cells in older pigs contributes to resistance in two ways. The increased proliferative capacity of crypt epithelium results in a more rapid regeneration of atrophic villi; and the comparatively young villous absorptive cells resulting from accelerated replacement produce less virus per cell than the older ones of the newborn pig.Transmissible gastroenteritis of swine is an acute diarrheal disease caused by destruction of absorptive epithelial cells of the intestinal villi by a specific coronavirus. The resultant lesion is called villous atrophy. Crypt epithelium is not affected directly by the virus, and intestinal villi rapidly regenerate in pigs that survive the acute diarrheal phase of the disease [16]. Acute viral diseases of the small intestine in several species follow a similar sequence of selective cell destruction, leading to variable degrees of villous atrophy and diarrhea, followed by rapid regeneration of villi and the return of normal function. Epizootic diarrhea of infant mice [ 11, lethal intestinal virus infec-

Observations suggest spring grazing of riparian areas is a good management strategy because of a reduced tendency for cattle to concentrate along streams during that season. In this study, June cattle distribution was examined within 4 experimental pastures located along Stanley Creek, Sawtooth National Recreation Area, Sawtooth National Forest, in central Idaho. Two pastures were grazed at a light stocking rate and 2 pastures were grazed at a medium stocking rate. Streamside graminoid utilization averaged about 24% under light stocking, while on the adjacent meadow graminoid utilization was 28%. Under medium stocking the average utilization at streamside was 37%, while that on the adjacent meadow was 50%. Residual herbaceous stubble heights under light stocking were 11 to 12 cm for both grazing locations, whereas streamside and meadow stubble heights were 10 cm and 7 cm, respectively, under moderate stocking. Cattle were not disproportionately attracted to the streamside areas during the June period. As stocking rates increased from light to medium, the cattle concentrated most of their additional use on the adjacent drier meadow. Utilization of riparhtn plant communities during this early summer period had no relationship to the amount of phmt moisture content, but was negatively associated with surface soil moisture.