Bu araştırma, düzenli östrüs gösteren ve göstermeyen ineklerde, siklus boyu kan serumu kalsiyum (Ca), çinko (Zn), bakır (Cu), potasyum (K) ve magnezyum (Mg) düzeyleri arasında bir fark olup olmadığını tespit etmek amacıyla yapıldı. Çalışma (1996 yılı Haziran-Ağustos ve 1997 yılı OcakrMart) aylan arasında, toplam 16 inekte yapıldı. İnekler Prpstaglandin F-2 alfa ile senkronize edildi. Prostaglandin F-2 alfa uygulamasını izleyerek östrüs gösteren tüm hayvanlardan, yaklaşık bir siklus süresince (20-24 gün) gün aşın kan örnekleri alındıöstrüslerden ortalama 21 gün sonra kızgınlık gösteren inekler düzenli östrüs gösterenler (A grubu), kızgınlık göstermeyenler ise düzenli östrüs göstermeyenler (B grubu) olarak gruplandırıldı. A grubunda, serum Ca düzeyinin siklusun 10 (P

This study was carried out to determine the presence of any differences between the serum levels of calcium, zinc, copper, potassium and magnesium in cows with regular and irregular estrus cycles. The study was conducted on a total of 16 cows between June-August of 1996 and January-March of 1997 year. The estrus cycles of these animals were synchronized using prostoglandin F-2 alpha and their blood samples were collected overnight during a cycle, starting on the following estrus of the synchronization. The cows having estrus around 21 days after synchronization were allocated to regular estrus cycle group (group A) and those with no sign of estrus at this particular time were allocated to irregular estrus cycle group (group B). Serum Ca level on days 10, 16, and-22, serum Zn level on days 8,16 and 18 and serum K level on days 0, 2, 8, 10 and 18, of the cycle were found to be significantly higher (P0.05). While mean serum levels of Ca, Zn, K and Cu obtained during the sexual cycle were found to be higher in group A than group B cows, difference between mean serum Mg level of these two groups was nonsignificant. When groups A and B were divided into winter and summer subgroups, it was observed that serum Cu, Mg and K levels in group B cows were lower in winter season than summer one. Howewer, there was no seasonal variation between serum Ca and Zn levels (P>0.05) in this group. In group A, serum Zn level was higher, but K was lower in winter than summer season. On the other hand, there was no difference (P>0.05) between winter and summer seasons of thesame group regarding to serum Ca, Cu and K levels. In conclusion, the findings of the present study show that serum Ca, Zn, Cu and K levels of cows with regular estrus cycle (group A) were significantly higher than those with irregular estrus cycle (group B), whereas difference between the serum Mg level of the same groups was nonsignificant.