Confronto della variabilità del casein number nel latte di bufala nell'azienda a conduzione biologica vs convenzionale

EVALUATION OF MILK CASEIN NUMBER VARIABILITY IN ORGANICAND CONVENTIONAL BUFFALO FARMS. During the twentieth century, milk production has profoundly changed, both in terms of quantity and quality, as a result of the introduction of new breeding techniques and genetic improvement that has affected the entire buffalo herd, as well as the effect of the 178 subsequent application, and ever more effective diffusion of new technologies for feeding and breeding. Considering that the buffalo milk is, almost entirely, intended for transformation in cheese; the attitude of coagulation is a vital requirement in the technical evaluation of the milk for the cheese processing. The casein number (CN), defined as casein nitrogen/total nitrogen, expressed as a percentage, is one of the most important parameters for assessing the suitability of milk for the production of "mozzarella" cheese. The aim of this research was to study the variability of the casein number of buffalo milk in relationship to the stage of lactation and to the breeding technology. The study was conducted on 140 individual milk samples of buffalo reared using organic methods and 140 milk samples of buffalo reared according to the conventional method. The samples were taken fortnightly always on the same animals, the entire lactation. The milk samples were divided into 8 intervals according to the distance from the delivery: 1(0-30); 2(31-60), 3 (61-90), 4 (91-120), 5(121-150); 6 (over 150). All samples were analyzed for protein content and casein , while the casein number was obtained as indicated previously . The data were analyzed with the ANOVA procedure of the statistical package SPSS. Figures 1 and 2 shows the trend in the total protein, casein and casein number in organic farm (Fig. 1 ) and in conventional farm (Fig. 2). The exam of both figures show how the parameters vary with the stage of lactation according to a similar trend in both farm, but it is equally clear the significant differences in the estimated values, for each parameter, between the conventional and organic farm. Moreover, it also appears evident that, while, in organic farm the trend of casein content is similar to that of casein number in conventional farm this does not happen. From this preliminary study, we can say that the breeding of organic management significantly improves the quality of the milk produced used for cheese processing. It is, however, necessary to further study the characteristics in coagulation function of all the parameters of quality of milk.