الفهرس 
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Abstract
The present study was applied through field survey in different regions of dairy cow farms (El-Sharkia and Alexandria governorates).A standardized data of 806 apparently healthy Holstein-Friesian cows was collected from reliable records stored in investigated farms. The data included age at first calving, calving season, parity, total milk yield (kg), days in milk (DIM), fat %, protein %, days to first insemination (DFI), days open )DO), calving interval (CI), number of services per conception(N/C), gestation length, and dry period. The incomplete records were discarded and avoided.Two statistical models were applied on this data.
Ι. First statistical model: Linear discriminant analysis (LDA) was applied to evaluate the association between milk production, reproductive performance, and calving season in dairy cattle. The results were summarized as follows:
There are three functions produced by discriminant analysis,305-day milk yield,days to first insemination (DFI), days open(DO), fat%and number of services per conception (N/C) have significant contribution in data classification of calving season. In the first function, there is a positive relationship between N/C with calving season,while 305-day milk yieldand days open showed a negative relationship with it. In the second function days to first insemination and days open were significant variables in discrimination between seasons of calving;where days openrevealed a negative relationship with calving season, while days to first insemination showed a positive relationship with it.
In conclusion:
1.Linear discriminant analysis is an efficient method for the discrimination between the group memberships (calving season).