The P4 movement in normal estrous cycle of crossed breed dairy cattle followed the regulation: the lowest on the day of estrus (0.17ng/ml), increased from day 3-9, reached the peak at days 1215 (2.19 - 2.20ng/ml), then decreased by day 18 and the lowest reduction was on day 21 (0.26ng/ml). Quantification of progesterone (P4) by EIA (Enzyme Immuno Assay) associated with ovarian rectal examination allows us to identify the exact causes of infertility cow (6-8 hours after sampling). The quantitative of P4 by EIA method combined with ovarian rectal examination in 31 retarded calving cows revealed that 11/31 (percentage 34.48 percent) retarded heat cows due to retained of corpus leteum
7/31 (percentage 22.58 percent) retarded heat cows due to cystic ovaries
9/31 (percent age 29.03 percent) retarded heat cows due to undeveloped ovaries and 4/31 (perceniage 12.91 percent) cows with normal ovarian activity.