Determination of progesterone directly in milk fat as an improved method for fertility control in cattle

A simple and reliable method for the determination of progesterone in milk fat by radioimmunoassay has been developed. Application of the assay under field conditions has shown that all samples diagnosed " questionable" in the former milk progesterone test (MPT) could be characterized as positive or negative. Thus the total figure of animals daignosed correctly rose from 72.3% to 85.8%. The borderlines (ng progesterone / 10 mcl milk fat) set up for this assay were (1) pregnant and (1) nonpregnant (Day 20) and (.3) in estrus and (.3) not in estrus ( Day 0). Within the application for diagnosis of pregnancy, 81.4% were diagnosed correctly as pregnant while 96.3% were diagnosed correctly as not pregnant. The latter figure is somewhat lower than in the MPT (100%), but under the practical conditions the error lies within the range of false diagnosis due to problems with sample identification.     

Epidemiology of leptospirosis in dairy farm workers in the Manawatu. Part II. A case-control study of high and low risk farms

Subsequent to a cross-sectional serological survey of Manawatu dairy farm workers, a case-control study was carried out to investigate the correlation between titres to leptospiral serovars in workers and those in cattle in their herds. A total of 52 herds was investigated, 25 of which were high risk where milkers had titres of 1:96 or greater, and 27 were case-controls where milkers had no detectable agglutinin titres at a minimum serum dilution of 1:24. The serological prevalence of titres to hardjo in cattle on high risk farms (76.5%) was significantly higher (P<0.05) than on the case-control farms (60.0%). The geometric mean titres of seropositive cattle on high risk farms were also significantly higher (P<0.01) than in the cattle from the case-control farms, especially in the younger cohorts. These findings suggest that there was active endemic hardjo infection in the two- to three-year-old cattle on the high risk farms. Titres to pomona were demonstrated in only 5.2% of the cattle from both types of farm. Workers with titres to pomona tended to be from farms on which stock, especially calves, were bought-in and pigs were kept. Conventional measures for protecting milkers from contact with infected urine appeared to be ineffective and it is concluded that prevention of leptospirosis in dairy farm workers can only be achieved by elimination of infection in the herd by vaccination of cattle.     

Radiographic changes in the lungs of horses with exercise-induced epistaxis

This paper describes the distinctive radiographic changes detected in the dorso-caudal lungfields of four racing thoroughbreds recently affected by exercise-induced epistaxis. A diffuse but localized increase in density was seen in all four cases, which demonstrated a variation from a predominantly alveolar density to an interstitial pattern and finally to increased bronchial markings. Evolution of the radiographic pattern of the pulmonary densities appeared to be related to the time that had elapsed since the bleeding incident. The implications of the changing pattern and site of the densities are discussed.     

Primary sulfates in atmospheric sulfates: estimation by oxygen isotope ratio measurements

The relative amounts of primary and secondary sulfates in atmospheric aerosols and precipitation can be estimated from measurements of the stable oxygen isotope ratios. The oxygen-18 content of sulfates formed in power plant stack gases before emission into the atmosphere is significantly higher than that of sulfates formed from sulfur dioxide after emission. Results show that 20 to 30 percent of the sulfates in rain and snow at Argonne, Illinois, are of primary origin.