Case Study: Combined risk factors and digestive disorders in mid-lactation Holstein cows
2022
Quanz, S.T. | Griswold, K.E. | Mamedova, L.K. | Kvidera, S.K. | Brouk, M.J. | Fry, R.S. | Bradford, B.J.
Digestive disorders can be a significant cause of disease in dairies and are frustrating because of their unpredictability. There is limited research on these conditions, and experimental exposure to individual risk factors often fails to cause disease. In this case study, we document the outbreak and resolution of digestive disorders among 15 control cows enrolled in a larger study. Over 14 wk, cows were individually fed, with milk yield and composition, blood variables, and health observations recorded. The diet included drought-stressed corn silage that introduced difficulties including low energy density, high DM content (making it unstable at feed-out), and mycotoxin contamination. By wk 4 to 5 of the study, fecal consistency decreased and milk fat content had dropped from 3.7% (±0.20) to 3.4% (±0.20), on average. Coincident with the onset of environmental heat stress, 3 cows developed severe digestive disorders, resulting in a displaced abomasum in one cow. At that point, the diet was changed to replace some corn silage with wheat straw, a direct-fed microbial was added to the diet, and organic acid treatment of the silage face was initiated. Within a month after these changes were implemented, essentially all signs of digestive problems resolved, including milk fat content, fecal consistency, and blood plasma concentrations of haptoglobin and d-lactate, although milk yield decreased. This case study points to multiple factors that likely combined to lead to microbial and gastrointestinal disruptions resulting in clinical disease in a subset of cows.
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