The aim of this study was to determine the difference in biochemical serum constituents of Arabian mares during different phases of the reproduction cycle. According to there reproductive status, mares were assigned to one of the following six groups, i.e., filly (n=5), late pregnancy (n=7), early pregnancy (n=11), estrual mares (n=8), infertile mares (n=8) and mares in post partum less than 8 days (n=4). Serum calcium, phosphorus, sodium, potassium, magnesium, glucose and triglycerides were determined. Calcium and phosphorus levels were significantly (P<0.05) higher in infertile and filly group, respectively. Sodium level was significantly lower in infertile than in all other groups and the higher serum level was observed in early pregnant mares. Concerning potassium, mean levels were significantly higher than in filly and the lowest mean values was observed in post foaling mares, however, no significant difference were observed in magnesium levels between all groups. Glucose concentration in early pregnant mares was lower than all other groups, but the difference was significant with mares in estrus and fillies. Triglycerides were significantly (P<0.05) higher in late pregnancy and infertile mares than in filly, in early pregnancy, in estrus and in post foaling mare groups. In this study, results pointed towards the significant influence of reproductive statues on some biochemical serum constituents in mares.

Key words: Arabian Mares, Glucose, Reproduction, Serum macro-minerals, Triglycerides