مجلة علوم ذي قار (Jun 2019)
Effect of Late Pregnancy, Parturition and Early Lactation on T3, T4and Cortisol Level of Heifers and Cows
Abstract
The present study was carried out in the Al-Dujalah Cows Station which is located in Wasit governorate, Iraq. From 305 crossbred cows (Holstein x Friesian breeds), thirty six heifers (2.5-3.5) years old and thirty six multiparous cows (5-7) years old at different physiological conditions. The heifers and cows were divided into six equal groups depending on their physiological conditions as follows, group 1: Non-pregnant heifers (control), group 2: (Heifers in 7th month of pregnancy), group 3: (Heifers in 8th month of pregnancy), group 4: (Heifers in 9th month of pregnancy), group 5: (Heifers at 1-4 hours of parturition), group 6: (Heifers in first month of lactation). The multiparous cows were divided as that of heifers. The blood samples (5ml) were collected from Jugular vein at 2 weeks interval during pregnancy, at parturition (1-4 hours after parturition) and first month of lactation and deposited into plastic tube without anticoagulant to obtaining the serum samples for hormonal analysis. The study revealed the following results: A significant increase (p?0.05) in serum (T4) level was recorded in last month of pregnancy in both heifers and cows compared with control and other studied groups and a significant decrease in T3 level was observed in 7th month of pregnancy, at parturition and first month of lactation in cows while there was a significant increase in T3 level was recorded in 9th month of pregnancy in heifers compared with control and other studied groups. A significant increase (p?0.05) in serum cortisol level was recorded in first month lactating animals compared with control and other studied groups in both heifers and cows, and a significant increase in serum cortisol level was observed in control, 8th and 9th month of pregnancy and at parturition in cows compared with that of heifers.
