Dairy production and sources of cellular variability of milk of cow's in two large farms in semi-arid environment (Tunisia coastal)
This investigation, referring to a description of the Individual Counts Cellular (CCI) of milk, accompanied by an analysis , so some quantitative and qualitative milk parameters that a number of physiological and zootechnical factors of cellular evolution, was performed on two large cattle farms conducted in semi-arid coastal environment (region of Sousse, Tunisia), subject tri-daily in mechanical milking room. It is especially striking that the arithmetic mean (MA) of the CCI cows's was 371000 cell. / ml, while the geometric mean (MG) of the CCI cows's was only 107500 cell. / ml. The median was 73,000 cells. / ml, value close to the MG and widely spaced from the MA, thus telling the usefulness of the MG. A great heterogeneity of cell quality of the milk was noted, however, without clearly identify correlation with the chemical composition of milk. In two large herds followed, the variation of CCI was inversely related to dairy productions. On the other hand, the CCI found an increase with the rank of lactation, the stage of lactation and the spring season of calving.
Keywords: Dairy cattle, Cellular Counts Individual, milk production level, quality milk, Factors of cellular variation, semi-arid coastal environment