The scrotal mange mite,Chorioptes bovis(Hering, 1845) on sheep: seasonality, pathogenicity and intra-flock transfer

Abstract

Abstract Lack of information on the seasonality and intra-flock transfer of mange in sheep caused by Chorioptes bovis led to this study and additional information was sought on the relationship between chorioptic mange and reduced fertility in rams. Romney rams and ewes were used throughout the study, and mites were collected by scarification of the scrotum and limbs. Individuals of one ram flock were examined for mites and lesions at monthly intervals over a 29-month period, and another flock was similarly sampled over 12 months. Ewes and their lambs were used in experiments to ascertain the spread of mange within a flock. Semen samples were taken from rams with scrotal lesions of different sizes and duration. The mite populations, and the lesions produced, exhibited a deasonal pattern. In rams, the prevalence of mange was high during the first and second year of life, decreased as the rams attained 4-tooth status and increased slightly the following year. It is not clear whether this is an age, or climate-related, phenomenon. In the ewes the prevalence of mites was always low, although mites were detected 6 weeks after birth in lambs born to one group of ewes. The absence of clinical symptoms of mange in rams did not necessarily indicate the absence of mites. There was no apparent relationship between the size and duration of scrotal mange lesions and semen quality.