Milk mainly composed of water, proteins (casein), sugar (lactose), fat and minerals (calcium and phosphorus). Also milk contains a few pigment, enzymes, vitamins, phospholipids and gas. A team showed a close relation between graziery feed composition, milk products quality and community health level. Although, statistical analysis in some references showed different correlations between milk parameters and consumed feed composition in grazieries. Currently, scientists are working hard on cow breeding programs to produce milk products having high values. The present work is concerned into adjusting the breeding program by defining the possible correlations between the repeatability of basic milk constituents. Different composite samples of herd milk have been collected in three periods [April-October, 2009] each month over an extended period of time. Twelve cows completed 27 scheduled sample days and five completed the first 18 days. Atmospheric records were gathered over 24-hr. during milk production. Some statistical components were estimated as the repeatability, variance due to days, and variance due to periods and the Chi-square was implemented to evaluate the differences between correlation coefficients. Low coefficients of variation have referred to the independent correlations among the variables in the breeding program.