The effects of monthly formalin treatments on the survival of salmonellae in earthen sheep yard debris |
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| Authors: | RA Robinson BVSc DipMicrobiol EH Shortridge MS BSc MRCVS Heather J MacDiarmid FNZIMLT |
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| Institution: | 1. Department of Veterinary Bacteriology and Public Health , University of Minnesota , St. Paul, U.S.A.;2. Department of Agriculture , P.O. Box 2298, Wellington;3. Ruakura Agricultural Research Centre , P.B., Hamilton |
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| Abstract: | Further field observations and laboratory studies on the biology and ecology of Damalinia bovis and Linognathus vituli, the two most common cattle louse species in New Zealand, are described. The life cycle of D. bovis was completed in 27–32 days while L. vituli took 26–31 days. The winter distribution of both species on individual animals was similar with the heaviest concentrations on the cranial half of the body. The effect of the haircoat composition on distribution was examined; correlations between louse counts and hair diameters, colour composition of hair populations, hair and debris density, and sample sites were estimated for both species. The only significant correlation of D. bovis counts was with sample site. Findings were similar for L. vituli except that there was also a significant correlation between louse numbers and weight of hair and skin debris. The importance of self-grooming is discussed in relation to louse distribution. Reasons for seasonal population fluctuations are considered including coat loss and temperature variations. It was shown experimentally that temperatures 5°C either side of the optimum 35°C prevented D. bovis eggs from hatching. |
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