رصد مستوى هرموني البروجستيرون و الأستراديول و علاقته بالبلوغ في عجلات البقر الشامي

الملخص EN

Twelve growing Shami heifers available in Dier-Al-Hajar Station for improving Shami Cattle weighing 115±3 kg and 178±4 days old were used to determine the weekly hormonal concentrations of progesterone (P4) and estradiol 17-β (E2) during the pre- and puberty stages (6-14 mos).

Blood samples were collected weekly from the Jugular vein using vacutainer tubes supported with K3EDTA.

Samples were dated and given identification numbers and left into ice box in a way to reach the analysis lab.

They were centrifuged for 15 minutes using cool centrifuge with a 3500 rotation/minute and then the plasma was separated, frozen and left in the freezer at -20 until the process of hormonal analysis took place using Enzyme Linked Immuno Sorbent Assay.

Results showed that there were significant differences (p < 0.05) between the monthly averages of esradiol and the concentration was increased as the animals advanced in their age and became closer to puberty.

The average concentration was 15.86 ± 0.86 pg/ml when the heifers were 6 months old and increased steadily with the age advances to reach 20.93 ±2.64 pg/ml at 14 months old.

However, these concentrations were higher with 3 to 5 times than those reported for international breeds.

On the other hand, no significant differences were recorded between the monthly averages of the concentrations of P4 and the general average was 0.29±0.01 ng/ml when the heifers were 6 to 13 months old.

A sharp increase (2.34±0.56 ng/ml) was observed when the animals reached 13 months old.

It was concluded that puberty occurs at 400 ±21 days old and 250 ±11 kg weight according to plasma level of P4 and E2 and it was suggested that further study is required to determine the reason(s) stand behind the increase level of E2 in Shami heifers.