The intensity of resistance by mature Merino ewes against Haemonchus contortus and Tichostrongylus colubriformis in single-species and combined-species infection

Three-year-old, non-lactating and non-pregnant Merino ewes, raised on pasture under a program of strategic treatment with anthelmintic and found to be extremely resistant to "trickle" infection with Haemonchus contortus, were given single-dose infections with either H. contortus or Trichostrongylus colubriformis or both species together. The purpose was to ascertain the intensity of protective immunity against the 2 parasites in sheep with immunity acquired from a presumably slight exposure to infection. To provide a criterion, some infected ewes were immunosuppressed with corticosteroid, dexamethasone. Untreated ewes were extremely resistant to challenge infection with either 15,000 or 150,000 H. contortus or 15,000 T. colubriformis. Surprisingly, when mixed infection was given, egg counts for H. contortus were significantly elevated compared with infection by that species alone. Antibody to antigens from infective larval and adult H. contortus was measured in serum by enzyme-linked-immunosorbent assay (ELISA) during the course of infection. Serum titres against larval antigens were significantly depressed when infections with either H. contortus or T. colubriformis were permitted by immunosuppression with dexamethasone, whereas those against adult antigen were depressed when infection with T. colubriformis was permitted.     

Artificial Insemination of Gilts with 1.5 Billion Sperms Stored in Different Periods Associated with Different Pre-ovulatory Intervals

This study evaluated the reproductive performance of gilts inseminated at three intervals before ovulation (0-12, 13-23, 24-30 h) with sperm doses (SD) stored for 0-48 and 96-120 h. A total of 218 PIC Camborough 22 gilts were inseminated once with SD of 1.5 x 10(9) sperms. Pregnant gilts (n = 166) were slaughtered 30.8 +/- 3.7 days after artificial insemination. The number of corpora lutea (CL) and total embryos (TE) was counted. Pregnancy rates (PR) were analysed by chi-square test. TE and embryonic survival (ES), obtained as the ratio between viable embryos and CL, were analysed by GLM procedure (SAS) and mean values were compared by Tukey's test. Pregnancy rate was similar among artificial insemination-ovulation (AIOV) intervals when semen was stored for 0-48 h. However, the lowest PR was observed in the 24-30 h AIOV interval with storage time (ST) of 96-120 h (p < 0.05). There was a significant effect of the interaction between ST and AIOV (p < 0.05) on TE and ES variables. Total embryos and ES did not differ (p > 0.05) among AIOV intervals in ST of 0-48 h. However, gilts inseminated at 24-30 h AIOV interval with ST of 96-120 h showed a reduction of 6.7 embryos (p < 0.05) compared with gilts in the same interval inseminated with semen stored for 0-48 h. ES for the 24-30 h AIOV interval and ST of 96-120 h was lower than that observed in the other groups (p < 0.05).     

Discovery of intense gamma-ray flashes of atmospheric origin

Detectors aboard the Compton Gamma Ray Observatory have observed an unexplained terrestrial phenomenon: brief, intense flashes of gamma rays. These flashes must originate in the atmosphere at altitudes above at least 30 kilometers in order to escape atmospheric absorption and reach the orbiting detectors. At least a dozen such events have been detected over the past 2 years. The photon spectra from the events are very hard (peaking in the high-energy portion of the spectrum) and are consistent with bremsstrahlung emission from energetic (million-electron volt) electrons. The most likely origin of these high-energy electrons, although speculative at this time, is a rare type of high-altitude electrical discharge above thunderstorm regions.     

Marketing Locally Produced Organic Foods in Three Metropolitan Arkansas Farmers’ Markets: Consumer Opinions and Food Safety Concerns

Consumers embrace local food systems as an alternative to the global corporate model, and nearly 75% of consumers in the United States purchase organic foods occasionally. To assess consumers’ knowledge of locally grown organic foods, surveys were administered at three metropolitan farmers’ markets in Little Rock, Hot Springs, and Texarkana, Arkansas. Consumers with Bachelor's, Associate's, or technical degrees accounted for almost half of the people surveyed. Seventy-one percent believed organic foods were safer than conventional foods. Three times as many consumers were concerned about harmful bacteria in conventional foods than in organic. The number one reason for purchasing was to support local farmers.     

Pharmacological differentiation of allergic and classically conditioned asthma in the guinea pig

A whole-body plethysmographic technique was developed and then used to detect experimentally induced asthma in guinea pigs and to assess pharmacological treatments of allergic and classically conditioned attacks. Inhalation of a beta adrenergic compound (isoproterenol) controlled both forms of attack. Atropine and methscopolamine, parasympathetic blocking agents, prevented conditional but not allergic attacks; diphenhydramine, an antihistamine, prevented allergic attacks; and methysergide, which blocks serotonin (which is believed to trigger human asthma), prevented neither. The guinea pig's allergic reaction is probably the result of a bronchospasm induced by histamine released in tissue of the airway by a local combination of allergen and antibody. The conditional attack is believed to be a constriction of the airway mediated by parasympathetic fibers of central origin.     

Iodine-131 in Utah during July and August 1962

Nuclear explosions in Nevada in July 1962 caused an average intake of about 58,000 picocuries of I(131) and a peak intake of 800,000 picocuries of I(131) by Utah residents consuming one liter of milk per day. Corresponding infant thyroid doses were about 1 rad (average) and 14 rad (peak).     

Disease-husbandry associations in farmed crocodiles in Queensland and the Northern Territory

SUMMARY To investigate husbandry-disease associations in farmed crocodiles 7 farms in Queensland and the Northern Territory were visited and details of past and present farm design and husbandry practices were recorded. In addition pathological examination of 300 (mostly young) crocodiles was carried out (85 necropsied, one biopsied and 214 examined retrospectively). Mortality rate and occurrence of disease, especially opportunistic infections with bacteria and fungi, were highest during winter months and in farms located at greater latitudes. A difference in the presence and prevalence of disease between the initial establishment phase of Northern Territory crocodile farms (1984–87) and currently (1988–91) was apparent; parasitic infections are now relatively infrequent and bacterial septicaemias and mycoses less common as a result of some provision of artificial heating for juveniles. Gross and microscopic changes observed in visceral and periarticular gout, bacterial hepatitis/septicaemia, deep and superficial mycosis, pentastomiasis and other parasitic infections are described.