摘要:

Linear and shell-weight indices of size inVenus mercenariafrom three widely separated regions of the Atlantic Coast, namely, Gulf of St. Lawrence, Chesapeake Bay and North Carolina have been studied. The maximum variations revealed in the "b" values for the linear dimensions ofVenusfrom the different regions are appreciable, whereas differences in the actual widths and thicknesses of corresponding lengths are not considered significant. The shell weights of specimens collected in the northern latitude of the Gulf of St. Lawrence are heavier than those from the warmer waters of the Chesapeake Bay and North Carolina. The length–shell-weight relations for the three regions are: Gulf of St. Lawrence, Wt. = 0.00000214L3∙003; Chesapeake Bay, Wt. = 0.00000171L3∙032; and North Carolina, Wt. = 0.00000108L3∙151. No significant correspondence exists between linear growth dimensional ratios and known environmental influences, whereas shell weights seem to correspond with the temperature factor, an inverse relation being the r

ISSN:1923-4287    

DOI:10.1139/cjr38d-001

出版商:NRC Research Press    

年代:1938

数据来源: NRC

摘要:

Series of samples taken at consecutive milkings were analyzed to determine the reliability of indirect biochemical tests (chlorides, catalase and pH) for the detection of chronic contagious mastitis. It was found that infected quarters not infrequently yield normal milk while many non-infected quarters yield milk giving definitely abnormal reactions. Furthermore, the reactions to these tests frequently fluctuate widely from milking to milking for both infected and non-infected quarters.These findings suggest the need of caution in the use of these tests as the basis for diagnosing mastitis infection, especially since the proportion of apparently normal animals showing abnormalities in the secretion is probably much larger in many herds than is generally appreciated.These studies emphasize the value of examining a series of samples at consecutive milkings in order to obtain a true picture of the condition of a quarter. They also suggest that of the three tests studied, the catalase test appears to be the most sensitive indicator of infection.

ISSN:1923-4287    

DOI:10.1139/cjr38d-002

出版商:NRC Research Press    

年代:1938

数据来源: NRC