[Cell concentration of individual cow's milk: effect of the status of mammary infection, parity, lactation stage and milk production].
The relative effect of the intramammary infections and of different factors related to the cow (parity, stage of lactation, milk yield) on the individual cell counts, were studied for 30 months on the 62 black-and-white Holstein cows of an experimental herd. During this period, the cows were regularly submitted to bacteriological tests for intramammary infections, individual cell counts and controls of the milk yield. The infection status of the cows at the time of counting was the main factor affecting the cell concentrations in the milk: the values ranged from around 5 X 10(4) cells/ml in the absence of infection in the four quarters, to values that were on average twice as high in the case of infection by a minor pathogen and ten times as high in the case of infection by a major pathogen. The mean cell concentrations in the milk of uninfected cows were significantly lower during the first lactation; they varied during the lactation according to a curve which had the form of an inverted lactation curve. The mean cell count during a lactation was independent of the mean milk yield per day of lactation. In cows infected by a major pathogen, the effect of the number and stage of lactation was different. Only the variation apparently associated with the stage of lactation had a sufficient amplitude to bring the mean cell concentrations of uninfected cows close to the values recorded in cows infected by a minor pathogen. The average results from cows infected by a major pathogen were, however, much higher at all stages of lactation.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D002417:Cattle / Q000502:physiology*; D002452:Cell Count; D005260:Female; D007774:Lactation; D008414:Mastitis, Bovine / Q000503:physiopathology*; D008892:Milk / Q000166:cytology* / Q000378:metabolism; D010298:Parity; D011247:Pregnancy
Concentration cellulaire du lait individuel de vache: influence de l'état d'infection mammaire, du numéro, du stade de lactation et de la production laitière.