The paper emphasizes the results of the research performed on 317 Romanian Spotted cows from six private exploitations located in the central part of the country. The main qualitative and quantitative traits of the milk production, season and familial structures (half sisters by father) effect were recorded in dynamics by four lactations on the above mentioned population. The research concerning the evolution of some traits of the quantitative and qualitative milk production in dynamics by

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... tion reveals many aspects, which in all cases equally reflects both the genetic potential of the biological material that can be expressed and putting into practice of the rearing and exploitation technologies. Concerning the quantitative milk production, by normal and total lactation an almost plane curve is described (Table 1, Figure 1). This aspect was also reported for the collecting areas and farms (Tables 2 and 3). Concerning the season effect, it is observed function of the adopted technology of exploitation, that for effectives is significantly observed only in summer (Table 4). In last part of the paper, the main traits of the milk production in 16 familial structures of primiparous half sisters by father, classified function of the quantity of fat and protein yield by normal lactation are emphasized (Table 5). The obtained results are concluding.