In order to study the effect of some parameters on the reproduction performances, a review of the reproduction of nine herds of dairy cattle located in the East of Algeria was established in a period of five years. The females demonstrated an infecundity following an extension of the interval between calving ICC= 405±50,9d, the interval calving-first service ICS1 =99±36, 5 as well as the interval calving-fecundate service ICFS =132± 25, 22. The fertility is good as the success rate at the first insemination SR1 and the fertility index are acceptable (SR1= 53, 8±21, 46 and IF= 1, 68±0,49 respectively). Simple correlations are investigated between different data of reproduction, thus between the parameters of reproduction and the other factors, susceptible to affect them. A correlation was proven between the interval calving-first service and the success rate at first service R=0, 74; also with the interval between calving ICC R=0,81. A strong correlation between the interval calving-fecundate service ICFS and the interval between calvings ICC was shown R=0, 86. The study of the models for the major livestock shows that the best model is obtained for the parameter interval between calving ICC and the interval calvingfecundate service ICFS (R2=80%). Another model highly significant was that between interval calving and the interval calving-first service (R2=70%), the other models are less significant. The effect of certain factors like age, number of lactation, season and moment of the realization of the first insemination and milk yield on different parameters of the evaluated reproduction parameters, was investigated, no correlation was highlighted. Nevertheless, the absence of the effect of the politic of the first insemination on the fertility of cows doesn`t exclude the importance of the choice of the moment and the season of the realization of the first insemination, because the excellent success rate obtained in spring is at (50- 70d) of the post partum SR1=72%. The knowledge of the risk factors, object of this study, helps to the establishment of an efficient strategy of control and monitoring in order to limit at least the lost in calves and in milk yield associated with bad performances.
