بررسي مقايسه‌اي غلظت ماهانه اوره در شير بز و ميش در يك دوره‌ي شيردهي

Monthly comparison of milk urea concentration in goats and ewes

اوره و مقادير آن در خون، ادرار، بزاق، عرق و ساير مايعات بدن بيانگر سوخت و ساز پروتيين‌ها و از انديس‌هاي مهم سلامتي در موجودات محسوب مي‌گردد. مقادير و ارزيابي اوره در شير نسبت به ساير مايعات كمتر مورد توجه قرار داده مي‌شود به همين منظور غلظت ماهانه اوره شير و ارتباط بين آنها در 220 راس بز و 136 راس ميش از ابتدا تا ماه پنجم شيردهي به روش برتوله مورد بررسي قرار گرفت. ميانگين اوره شير بز از يك تا پنجمين ماه شيردهي و در مجموع به ترتيب 2/35، 9/30، 7/19، 27، 4/35 و 6/28 و اوره شير ميش 7/21، 9/41، 2/41، 9/36، 2/50 و 7/36 ميلي‌گرم در دسي‌ليتر تعيين گرديد. دامنه‌ي تغييرات اوره شير بز و ميش در طي شيردهي به ترتيب بين 27/7 تا 7/72 و 9/11 تا 1/89 ميلي‌گرم در دسي‌ليتر متغير بود. مقايسه ميانگين غلظت اوره شير بز و ميش در پنج ماه شيردهي معني‌دار بوده است (P < 0.01). غلظت اوره شير بز در ماه سوم با بقيه ماهها (P < 0.05) و غلظت اوره شير ميش در ماه اول با تمامي ماهها معني‌دار بوده است (P < 0.05). حضور اوره در شير بز و ميش مشخص شده بود و مقدار آن در شير ميش بيشتر از بز بوده كه از نظر اقتصادي و بهداشتي نيازمند بررسي است. فقدان ارتباط بين اوره در ماههاي شيردهي در بز يا ميش بيانگر اختلافات متابوليسمي در روند فيزيولوژيك حيات دام مي‌باشد.

Monthly comparison of milk urea concentration and their interrelationships were studied in 220 goats and 136 ewes in 2005-6 in Urmia. The amount of 50 ml milk was prepared monthly up to 5 months. Milk urea concentration was evaluated by Bertholet method using urea kit (Ziest-Chimi, Iran) in spectrophotometer. Mean for goat’s milk urea concentration (GMU) from one to 5 months and overall were 35.2, 30.9, 19.7, 27, 35.1, 28.6 and for ewes milk urea (EMU) were 21.7, 41.9, 41.2, 36.9, 50.2, 36.7 mg/dl, respectively. GMU concentration decreased irregularly while EMU increased regularly during the lactation. The range for the whole period of lactation for GMU and EMU were from 7.74 to 72.7 and 11.9 to 89.1 mg/dl, respectively. Mean comparison of the GMU and EMU showed differences (P < 0.01) among lactation months. Mean GMU at 3 months and EME at first month were different from other months of lactation. There was no correlation among lactation months in GMU and EMU, but correlation was found between GMU at 2 and 4 months of lactation (r=0.40, P < 0.01) It is concluded that milk urea concentrations in goats and ewes were different during the lactation months but they were at the recommended level in bibliography. The presence of differences between GMU and EMU during the lactating months were the reflection of the metabolism and physiological procedures, but the differences were statistical and not biological values. Urea was confirmed in milk goats and ewes and the concentration in ewes milk was greater than in goats milk that requires further study in relation to economic and hygiene importance. The lack of correlations between parameters under study shows their non-independent characteristic in source of their production.