Evaluation of Control Program of Maedi-Visna by Foster Feeding with Cow Colostrum and Other Measures

A serological and clinical case control study of Maedi-visna virus (MVV) infection in sheep was carried out at the sheep ranch of Sheno Agricultural Research Center from November 2004 to March 2005 with the objective of characterization the clinical and pathological features of the MVV disease in the center and to evaluate the effectiveness of the control program that practiced in the ranch to produce MVV free flocks. A total of 250, Yearlings (125) and Ewes (125) serum samples were collected and Agar Gel Immunodiffusion (AGID) test was used to identify the presence of antibodies against MVV infection. All sampled sheep were clinically examined whereas few seropositive sheep were examined for gross and histopathological lesions. The overall seroprevalence of MVV infection in the station was 176(70.4%). Therewas statistically significant difference (P<0.000) between the two feeding types in the mean seroprevalence of the yearling sheep that were fed on their dam colostrum and milk was 79(79%) and that were fed with cows colostrum and milk 0 (0%). The seroprevalence of MVV infection varied significantly (P < 0.05) between Awassi 19(38%), crosses 33(66%) and local Menze 124(82.7%). MMV infection increased with increasing age of sheep from 80(64%) in yearlings with out considering the rearing type to 100%) in seventh years old and hence, the seroprevalence was also significantly different (P < 0.05) with the variation in age. 21 (11.9% ) MVV seropositive sheep were found to express the clinical disease.The serological and clinical findings suggested that MVV infection is a major health problem in the center. Based on the above result, artificial rearing by isolation of ovine colostrum deprived lambs offers an effective method of maedi-visna control that could be successfully applied in station.