Comparison of ketosis, clinical mastitis, somatic cell count, and reproductive performance between free stall and tie stall barns in Norwegian dairy herds with automatic feeding.

Differences in ketosis and clinical mastitis rates, mean somatic cell counts (SCC) and reproductive performance scores (fertility status index = FS-index) between herds housed in free stall (n = 533) and tie stall (n = 59) barns were measured in relation to management and environmental factors in a retrospective cohort study of Norwegian dairy farms with automatic grain feeding systems. Herds with tie stalls were found to have a higher clinical mastitis rate, (61.6 cases per 100 cow-years versus 46.4 cases per 100 cow-years (p < 0.01)); a significantly higher proportion of herds with ketosis, (relative risk = 1.59, (p < 0.01)); and a lower mean fertility status index, (67.3 versus 82.8 (p < 0.01)). No significant difference in mean SCC was found between the 2 groups of dairies (p = 0.32). Large herds had higher Loge geometric mean SCC than small herds (p < 0.01) and herds with high SCC had lower milk production than herds with low SCC (p < 0.01). Herds that scored "very good" on cow cleanliness had significantly lower adjusted mean SCC than herds with scores of "average" or "good" (p < 0.05). Herds in barns with a concrete floor had an adjusted mean number of cases of clinical mastitis of 51.4 per 100 cow-years, 14 per cent higher than herds in barns with rubber mats, litter bed or wood (45.2 cases per 100 cow-years) (p < 0.05). Herds with high milk production level had higher FS-index than herds with low milk production (p < 0.01). Lower disease rates and the higher fertility status measured in the present study favor free stall herds over tie stall herds.