Effect of precooling incubation time on the efficiency of added antibiotics on total bacterial count and viability of frozen ram semen

A total of 16 pooled raw ram semen samples were collected from healthy rams cross bread (Rahmani & Barki). Semen samples of at least 70 % initial sperm motility and 3000 x 106 sperm / ml were used. Semen samples were tested bacteriologically through determination of total colony count, Enterobacteriaceae count and staphylococci count. Additionally, percentage of sperm motility, percentage of live sperm and total abnormality percentage were performed at 0, 30 and 45 minutes after dilution and holding at 35°C, then freezing process of semen was carried out at the previous time. The post thawing semen samples were evaluated as percentage of post thawing motility, viability index and acrosomal defects. Bacteriological examination of post thawing semen samples was also done at the same time intervals. At 35°C, the percentage of alive sperm increased significantly (P < O.05) at 0 minute than at 30 min. and 45 min incubation. The percentage of sperm motility was non significant between 0 min. and 30 min., while it was decreased significantly (P < 0.05) at 45 min. The percentage of sperm abnormalities decreased significantly (P < 0.05) at 0, 30 and 45 min. The post thawing motility was highy significant (P < 0.05) at 30 min. than 0 min. and 45 min. The viability index decreased significantly (P < O.05) at 0, 30 and 45 min. respectively, while post thawing acrosomal defects showed non significant difference between 0 min. and 30 min., but increased significantly (P < O.05) at 45 min. Before, freezing and post thawing, the total bacterial and Enterobacteriacea counts at 0 time were the highest values, which decreased at 30 min. At 45 min. the total bacterial and Enterobacteriacea counts increased than that at 30 min. The staphylococci count was detected with low value at 0 min. and not detected at 30 and 45 min. before freezing, while it wasn't detected in the post thawing samples at all times. The obtained results revealed that the best time for antibiotic action on semen was 30 minutes before freezing process. تناولت الدراسة تجميع 16 عينة من السائل للكباش، حيث تم اختبار هذه العينات المجمعة من كباش ناضجة جنسيا خليط (رحماني و برقي)، بحيث لا تقل حركة السائل المنوي لهذه العينات عن 70% و عدد الحيامن عن 3000 × 106 لكل مللي لتر و عمل تخفيف للسائل المنوي و تقييمه (نسبة الحركة التقدمية، نسبة الحيامن الحية، نسبة الشواذ الحيامن) عند درجة 35ºم لمدة 0.30 و 45 دقيقة كما تم تجميد السائل المنوي و عمل تقييم لنسبة حركة الحيامن بعد الإسالة و نسبة تشوهات الأكروسوم و كذا معدل الحيوية