EFFECTS OF CAPRINE ARTHRITIS-ENCEPHALITIS VIRUS ON PRODUCTIVITY AND HEALTH OF DAIRY GOATS IN NEW-SOUTH-WALES, AUSTRALIA

The effects of caprine arthritis-encephalitis virus (CAEV) on performance of a dairy goat herd during a 2 year period were examined. The herd comprised approximately 200 head including 57-80 lactating does. A significant increase (P < 0.05) due to CAEV was apparent for reproductive failure among multiparous does (43% vs. 18%). Kid birth weights (mean +/- SE 3.4 +/- 0.1 vs. 3.6 +/- 0.1 kg) and growth rates prior to (148 +/- 14 vs. 194 +/- 5 g day-1) and during the weaning period (34 +/- 20 vs. 111 +/- 28 g day-1) were also adversely affected in kids of CAEV infected does (P < 0.05). Seropositive multiparous does had lower 300-day yields of milk (357 +/- 27 vs. 445 +/- 271) and had reduced lactation lengths (272 +/- 7 vs. 293 +/- 5 days) compared with seronegative does (P < 0.05). However, differences in monthly test-day results were significant (P < 0.05) for yields of milk protein and milk fat only when supplementary nutrients were fed at a low level (150 g dry matter (DM) per doe day-1) compared with higher levels (over 0.93 kg DM per doe day-1). In addition, the incidence of diseases was greater among does seropositive for CAEV (P < 0.05). The results demonstrated that CAEV affects the productivity of older does more than that of younger breeding age does, support suggestions of immunodeficiency due to CAEV, and provide some evidence of interactions between CAEV, nutrition and stressors. They provide further evidence of adverse effects of CAEV in dairy goat herds.