Rates of diagnosis of six diseases of Holstein cows during 15-day and 21-day intervals
Erb, H.N.; Smith, R.D.; Hillman, R.B.; Powers, P.A.; Smith, M.C.; White, M.E.; Pearson, E.G.
American Journal of Veterinary Research 45(2): 333-335
1984
ISSN/ISBN: 0002-9645 PMID: 6711956 Document Number: 230611
The lactations of 3172 Holstein dairy cows were divided into intervals of 15 and 21 days. The numbers of new diagnoses of metritis, cystic ovary, miscellaneous reproductive disorders, mastitis, left displaced abomasum, and milk fever in each interval were counted. The numbers of cows at risk in each interval were also counted. A cow was at risk if still milking in the herd, and a diagnosis had not already been made for that condition in that lactation. A cow was also at risk if not pregnant. For each interval, the incidence rate of new diagnoses was calculated by dividing the number of new diagnoses by the number of cows at risk. Metritis, mastitis, left displaced abomasum occurred mostly in the first month of lactation, although they continued to be diagnosed through the fifth month. Milk fever occurred (apart from one case) in the first month of lactation. Cases of ovarian cysts peaked around the second month of lactation.