The effect of a natural maedi-visna virus infection on the productivity of South African sheep

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 natura...

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Veröffentlicht in:Onderstepoort journal of veterinary research Jg. 67; H. 2; S. 87
Hauptverfasser: Dungu, B, Vorster, J, Bath, G F, Verwoerd, D W
Format: Journal Article
Sprache:Englisch
Veröffentlicht: South Africa AOSIS (Pty) Ltd 01.06.2000
Schlagworte:
Animals
Antibodies, Viral - blood
Cohort Studies
Female
Growth Disorders - pathology
Growth Disorders - veterinary
Growth Disorders - virology
Lymphocytes - pathology
Male
Mammary Glands, Animal - pathology
Mastitis - physiopathology
Mastitis - veterinary
Mastitis - virology
Milk - chemistry
Pneumonia, Progressive Interstitial, of Sheep - pathology
Pneumonia, Progressive Interstitial, of Sheep - physiopathology
Pneumonia, Progressive Interstitial, of Sheep - virology
Sheep
South Africa
Visna-maedi virus - immunology
Visna-maedi virus - pathogenicity
South Africa
ISSN:0030-2465, 2219-0635
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Beschreibung
Zusammenfassung: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.
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ISSN:0030-2465
2219-0635