This study was conducted on 30 Friesian cows in Joub-Ramlea station at the south side of El-Ghab valley in Syria which characterize with soil fertilizing, more raining and more under ground water saving. The objective was to investigate the effect of milk quantity on the milk components especially fat and protein. The animals divided into three groups. Each group included 10 cows. The milk components was studied in each group during three stages : In the beginning of lactation (the second

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... , in the middle of lactation (the fourth month), and in the last of lactation (the sixth month). Results, showed that the differences in milk quantity among studied groups, were highly significant, where, milk quantity for high performance group was 5843 kg during lactation, compared 3275 kg with of low performance group. This evidence difference in yield indicated to wide range in major genes among cow individuals in spite of their same environment conditions. The findings illustrated that the differences in protein and fat percentages were in agreement with natural changes, where the percentages were higher in low performance ones. The results also indicated that the protein and fat percentages increased with the advancing.