LAUSR

| Bovine leukemia virus (BLV) is a retrovirus, affects lymphoid tissue and causes malignant lymphoma and lymphosarcoma. There is strong evidence that BLV has deleterious impact on fertility and milk production of animal. The main objective of the present study was therefore to characterize the impact of BLV infection on reproduction efficiency and milk production in water buffaloes and Holstein-Friesian cattle raised in Egypt. The study was conducted on 100 buffaloes from one herd and 350 cows from three different herds to investigate antibodies against BLV and its association with service per conception (SPC) and milk production. The results revealed significant (P=0.001) increases in SPC in seropositive-buffaloes (N=9) compared to healthy buffaloes (N=91). However, no significance difference in SPC between seropositive and seronegative cows. The seropositive buffaloes showed significant (P<0.05) reduction in days in milk, daily milk and total milk production (N=9) than the seronegative buffaloes (N=91). Similar to SPC result, the seropositive cattle didn’t show reduction in milk production. In conclusion, BLV infection has more injurious impact on the reproductive performance and milk production in water buffaloes than dairy cattle. Therefore, this study recommends effective prevention strategies against BLV infection in water buffaloes farms in Egypt.