Effect of Prepartum and Postpartum Diet on Histamine Metabolism of Young Holstein Cows

Abstract

Animals preconditioned with low levels of concentrate for three to four weeks before changing to a high-concentrate diet at parturition showed higher histamine concentration in the rumen (P<.05) than those going from an all-hay diet to a high-concentrate diet, or than those on a low-concentrate diet during the postpartum period. These higher levels of histamine could not be related to a reduction in rumen pH. Increases in plasma histamine concentration (P<.05) during the postpartum period did not appear to be related to the elevations observed in the rumen. A higher (P<.01) histamine concentration was found in mammary secretions obtained before parturition than in those obtained after parturition. An increase in blood glucose (P<.01) on the day of calving did not appear to be due to dehydration, because a similar response was not observed in hemoglobin. Treatment-related health disorders were observed in two animals. Whereas histamine may have been responsible for the manifestation of some of the observed symptoms, other undetermined factors must be involved, because cows in groups with the highest histamine levels were not adversely affected.