Effect of seropositivity to bovine leukosis virus, bovine viral diarrhea and neosporosis on productive and reproductive indices in dairy herds

The objective was to compare seropositive and seronegative animals to bovine leukosis virus (BLV), bovine viral diarrhea (BVD) and Neospora canis (Nc) in seven productive characteristics (adjusted milk production (PDNa), percentage of adjusted protein (PPa), kilograms of adjusted protein (KgPROa), percentage of adjusted fat (PFa), kilograms of adjusted fat (KgFa), somatic cell score (SCS), all adjusted to 305 days, and duration of lactation (DurL)), and in six reproductive characteristics (age at first service of heifers (AgeFSh), services per conception in heifers (SCh), services per conception in cows (SC), age at parturition (AgeP), days open (DO) and calving interval (CI)). The presence of BLV resulted in low levels for KgPROa, KgFa, and high CI in infected cows. For AgeP, SCh and SC there was no effect of BLV seropositivity. It was a tendency of BLV to affect negatively AgeFSh, PDNa, DO, and SCS. Nc presence had negative effect on SC. A tendency to present a negative effect by DVB was found for PDNa; a significant effect of the interaction between DVB-Nc pathogens on PFa was found, and a tendency to present a negative effect of the interaction between DVB-Nc on KgFa and between BLV-DVB on CI.