Effects of bovine leukemia virus infection on production and reproduction in dairy cattle.

摘要: The purpose of this study was to determine the effects bovine leukemia virus (BLV) infection on production, reproduction and longevity in dairy cattle. population a commercial Holstein herd approximately 400 milking cows. Cattle were tested for antibodies BLV at least annually three years when culled. Four groups culled cows compared: seronegative (n = 79), seropositive without lymphocytosis 176), with (> or 9,000 lymphocytes/microliter) 74), lymphosarcoma 29). Seropositive bred more times had longer calving intervals than greater 305-day ME (mature equivalent) FCM (3.5% fat-corrected milk) per lactation older However, percent fat In last complete lactation, differences FCM, days open cull age between reduced none significant (p > 0.05). only milk production relative cows, although difference not significant. After adjustment initial reproductive values, nonlymphocytotic significantly Lymphocytotic four months younger average Hence, infected uninfected Adverse primarily limited lymphocytotic which earlier lactation.