Effects of a Dietary Multi-Mineral Bolus on Udder Health in Dairy Cows: A Clinical Assessment

The clinical effects on the udder health of several trace elements—copper, iodine, cobalt, and selenium—contained in an intraruminal slow-release bolus were explored for the first time. Fifty-four dairy cows received the bolus (treated group, TG), while fifty-three were left untreated (control group, CG). Monthly composite milk samples were collected from 30 to 300 days in milk to measure somatic cell count (SCC); milk production was also recorded on the same days. Cows with SCC > 200 × 103 cells/mL were considered as affected by mastitis (with or without clinical signs). The effects on udder health were evaluated using several clinical indices employed for mastitis monitoring. The TG cows had a higher average daily milk yield than CG (p < 0.001), as well as a lower overall daily average of SCC (p < 0.0001). Fewer overall mastitis cases were detected in TG than in CG (p < 0.0001), although no significant differences were observed in new or cured mastitis cases. Finally, fewer failures of existing mastitis to cure cases were detected in TG as compared to CG (p < 0.0001), as well as fewer chronic mastitis cases (p < 0.0001). By looking at the clinical findings, some potential benefits on udder health might be hypothesized; nevertheless, additional studies are necessary to confirm these encouraging results.