ANALYSE DESCRIPTIVE ET FACTEURS D’ÉVOLUTION DES NUMÉRATIONS CELLULAIRES INDIVIDUELLES DU LAIT CHEZ DES PETITS TROUPEAUX BOVINS HORS SOL DANS LA RÉGION DE MONASTIR (TUNISIE)

Abstract

The objective of this study is to analyze the variation of individual cell counts (CCI) of cows during an entire lactation while insisting on the effect of main variables of evolution. The monitoring was conducted on a sample of 40 non-grazing cattle farms in the region of Monastir (Tunisia). Mammary health diagnosis was performed by the method of direct cell count on individual cow milk using a cell counter of type Fossomatic4000. It appears from this study that CCI distribution, according to two rules estimation, gives two different results for the samples of healthy milk. In fact, 48% of samples correspond to a normal or healthy milk with CCI ≤ 200000 cell. / ml, while 57% of the samples are from healthy udders with CCI ≤ 300000 cell. / ml. It also noted that 66% of cows have arithmetic CCI > 200000 cell. / ml, whereas 52% of cows present geometric CCI > 200000 cell. / ml. In this overall context, and to better assess the distribution of CCI, it was used quartiles diagram which confirmed the reliability of using the geometric method for the study of CCI. In addition to the variation of CCI according to the study methodology, changes can result from physiological factors related to the cow. Indeed, the CCI are lower in the beginning of lactation for primiparas compared with the end of lactation and multiparas. For the relation between milk production and CCI, this latter was recorded lowest at peak lactation of cows. These results coincide exactly with those reported in previous studies