Abstract
Summary
1. The average plasma prothrombin time value of 115 matured dairy cows was 23.20 ± 4.42 and for 90 dairy calves 24.82 ± 4.47. The differences in the prothrombin time values among 6 herds of Jersey cows were highly significant (1% level) and significant 5% level) among breeds between Jerseys and Guernseys. The principal factor contributing to these effects was ascribed to rations. Age, breed, ration, and sex did not alter the prothrombin time values of dairy calves. 2. The holding of the blood plasma samples for 2.5 and 3.5 hours after collection of blood samples did not change the prothrombin time significantly when compared with the 0.5 hour values. 3. The plasma prothrombin time of newborn calves, prior to nursing, could not be determined since a clot or gel did not form in the blood plasma-thromboplastin mixture after the addition of calcium chloride. This finding corresponds with the observations made with blood plasma from human infants during the first week of life. 4. The average hematocrit value of 92 dairy cows consisting of Jersey, Guernsey, Ayrshire, and Holstein breeds was 35.08 ± 3.30. Breed differences in hematocrit values were not present; however, the differences among herds of the Jersey breed were significant at the 5 % level.
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