The objective of this study was to evaluate eight cowside ketone tests when used with milk for detection of subclinical ketosis. A total of 469 dairy cows in the first week of lactation were studied. Twelve percent of these cows had subclinical ketosis, defined as >1400 micromol of beta-hydroxybutyrate/L of blood serum. The Pink test liquid and the Ketolac test strip were highly sensitive for subclinical ketosis when used with milk. The Uriscan and Rapignost test strips were poorly sensitive; the Ketostix, Ketur-Test, and Medi-Test-Keton test strips and the Acetonreagenz test tablet were insensitive for subclinical ketosis when used with milk. Pink and Ketolac milk ketone tests are potentially useful tools for use in a routine monitoring program to detect subclinical ketosis in early postpartal dairy cows.

The objective of this study was to evaluate the characteristics of five ketone tests for use with milk to detect subclinical ketosis [defined as > 1200 mumol of beta-hydroxybutyrate (BHBA)/L of blood] in dairy cows. The tests studied were the Ketolac BHB strip to detect BHBA (Hoechst, Unterschleissheim, Germany) and four tests based on sodium nitroprusside to detect acetoacetate (Rothera tests) [Ketostix strip (Bayer, Etobicoke, ON, Canada), Bioketone powder (Societé d' Analyses Biopharmaceutiques, Laval, QC, Canada), Ketocheck powder (Great States, St. Joseph, MO), and Utrecht powder (University of Utrecht, Utrecht, The Netherlands)]. Milk samples (n = 529) from 266 cows in 25 Ontario dairy herds were used for this investigation. The Ketolac BHB strip at 50 and 100 mumol of BHBA/L of milk showed sensitivities of 92 and 72%, respectively. This test was more sensitive for subclinical ketosis than were any of the Rothera tests. The sensitivities of the Rothera tests were 43, 33, 28, and 5%, respectively, for Utrecht powder, Bioketone powder, Ketocheck powder, and Ketostix strip. The Rothera tests were highly specific, as was the Ketolac BHB strip at 200, 500, and 1000 mumol of BHBA/L of milk (specificity, > 97%). The prevalence of subclinical ketosis was highest during the first 6 wk of lactation, and a peak was detected during the 2nd wk of lactation. Of the tests evaluated in this study, Ketolac BHB strip was the most useful to monitor subclinical ketosis in dairy herds.

Summary Literature on the subject of character, history, occurrence, causes and pathogenesis of abomasal displacement in the bovine is listed and summarized. The chapter on occurrence is subdivided according to heritibility, sex, age, season, husbandry, milk yield and concomitant diseases. In the chapter on causes special consideration is given to feeding. The chapter on pathogenesis is subdivided according to mechanical influences, disturbances of the abomasal motor activity, collection of gas and dilatation of the abomasum and artificial displacement of the abomasum. Displacement of the abomasum is seen predominantly in the spring in herds with above‐average milk yield in dairy cows between the age of 4 and 7 years which have calved within the last month and have ketosis. The etiology and pathogenesis of abomasal displacement are unclear.

The objective of this study was to evaluate factors associated with ruminal pH at herd level. Four hundred and thirty-two cows of a Thuringian dairy herd were sampled before claw trimming using a rumen fluid scoop. Volume and pH of the rumen sample were measured, and lactation number, percentage of concentrates in the ration, days in milk (DIM), time of day, and daily milk yield were recorded. Rumen sampling was successful in 99.8% of the cows. The average sample volume was 25 mL. Rumen sample pH decreased with increasing percentage of concentrates in the ration. Ruminal pH decreased from calving to 77 DIM, and grew subsequently to 330 DIM. During the day, rumen pH followed a sinus curve, with maxima in the morning (0915 h) and afternoon (1533 h), and a minimum around noon (1227 h). Ruminal pH decreased with increasing daily milk yield. Lactation number interacted with daily milk yield on rumen pH. The percentage of concentrates in the ration, DIM, time of day, and daily milk yield were significant factors affecting ruminal pH at the herd level.

The objective of this study was to analyze the survivorship of dairy cows after displaced abomasum was diagnosed. Survivorship from the calving preceeding diagnosis of displaced abomasum to removal from the herd was investigated for cows that were diagnosed with displaced abomasum compared with herdmates. For cows that were diagnosed with displaced abomasum, factors that affected survivorship from the diagnosis of the disease to removal were investigated. Data from a total of 135 cows that had been diagnosed with displaced abomasum and 373 controls matched by herd and lactation number were available from a database at the University of Guelph. The hazard rate of removal from the herd was estimated using proportional hazard regression adjusted for intraherd correlation. Diagnosis of displaced abomasum significantly increased the hazarad rate of removal from the herd. For cows that were diagnosed with displaced abomasum the hazard rate of removal increased as parity increased. However, the hazard rate decreased with recurrent displaced abomasum and with higher days in milk at diagnosis of the disease. Although the 305-d milk production of cows that were diagnosed with displaced abomasum was lower during the lactation when the disease was diagnosed, 305-d milk production was not associated with removal of cows with that disease from the herd. Milk production during subsequent lactations did not differ between cows that were diagnosed with displaced abomasum and control cows. Low milk production during the subsequent lactations increased the hazard of removal of cows with that disease from the herd.