The effect of a natural maedi-visna virus infection on the productivity of South African sheep.
نویسندگان
چکیده
A cohort study was conducted in order to measure the effect of the chronic indurative lymphocytic mastitis caused by the South African strain of maedi visna virus (MVV) on the pre-weaning growth of lambs born either of naturally infected or uninfected ewes kept under similar conditions. Fifty naturally infected ewes as well as another 40 from a maedi-visna-free source to be used as control animals, were purchased and kept in separate flocks which were managed in a similar way. All the ewes were of the same breed and 3-4 years old. During the adaptation period, and through the mating, pregnancy and lactation periods they were periodically monitored for the presence of MVV serum antibodies. The lambs were weighed at birth and thereafter every 2 weeks until the age of 90 days, when they were weaned. The ewes were then slaughtered, and their udders examined histologically and the number of lymphocytic follicles were counted and assessed. Although the calculated values indicated a correlation between the number of follicles in the udder and the reduction in the growth rate of the lambs, this was not statistically significant. Similarly, despite higher counts of lymphoid follicles in the udders of sero-positive ewes as compared to those that were sero-negative and the lower ewe productivity indexes in infected ewes, no statistically significant differences were found in the indexes of ewes in different follicle categories.
منابع مشابه
Vaccination delays maedi-visna lentivirus infection in a naturally-infected sheep flock
BACKGROUND The Maedi-Visna (MV) lentivirus causes two slowly progressive eventually fatal diseases of sheep, Maedi, a progressive interstitial pneumonia, and Visna, a progressive demyelinating disease of the central nervous system. Other lentiviruses also cause fatal slow infections in their natural hosts, e.g. the HIV virus in humans. Results of experimental vaccination against any lentivirus ...
متن کاملCaprine Arthritis and Encephalitis
Caprine arthritis and encephalitis (CAE) is an economically important viral disease of goats. The caprine arthritis encephalitis virus (CAEV), a lentivirus; infects its hosts for life. Although most infections are subclinical, a minority of animals develops progressive, untreatable disease syndromes including polyarthritis in adults and encephalomyelitis in kids. This virus also causes indurati...
متن کاملCaprine Arthritis and Encephalitis
Caprine arthritis and encephalitis (CAE) is an economically important viral disease of goats. The caprine arthritis encephalitis virus (CAEV), a lentivirus; infects its hosts for life. Although most infections are subclinical, a minority of animals develops progressive, untreatable disease syndromes including polyarthritis in adults and encephalomyelitis in kids. This virus also causes indurati...
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ورودعنوان ژورنال:
- The Onderstepoort journal of veterinary research
دوره 67 2 شماره
صفحات -
تاریخ انتشار 2000