الفهرس 
REVIEW OF LITERATURE
Oestrous activityOnly 14 pages are availabe for public view
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Abstract
This study was carried out at Animal Production Department, Faculty of Agriculture, Mansoura University and the field work was carried out at the Experimental Station, Sakha, belonging to Animal Production Research Institute during the period from December, 2006 to December, 2007. 1. First trial (Treatment of mature ewes): Total number of 40 mature healthy crossbred ewes (1/2 Finnish Landrace x 1/2 Rahmani) having 3-4 years of age were divided into two equal groups (control and treatment), according to their live body weight and age. Ewes in the first group were served as a control group without injection, while those in the second group were treated with a subcutaneous injection of 160 mg rbST at 14-day intervals from one-month pre-partum up to insemination. Laparoscopy was performed during the period from day 7 to day 12 after first oestrus and mating. Ewe lambs were deprived from feeds and water for 24 hours prior to laparoscopy examination. 2. Second trial (ram lambs produced from ewes in the 1st trial): After weaning at 2 months of age, male lambs from rbST treated ewes were subcutaneously injected with 80 mg rbST at 14-day interval (treated group). However, male lambs of the control ewes were served as control group. Male lambs in the two experimental groups were subjected to observation to detect changes in sexual behaviour, once every 10 days interval during the period from 6 months of age till the onset of puberty (first successful ejaculate with motile sperm), and then age at puberty was recoded. 3. Third trial (ewe lambs produced from ewes in the 1st trial): After weaning at 2 months of age, female lambs from rbST treated ewes were subcutaneously injected with 80 mg rbST at 14-day interval (treated group). However, female lambs of the control ewes were served as control group. Age of puberty was recorded when ewe lamb start to exhibit its first oestrus behaviour. At 4 months of age, teaser rams were introduced to the ewe lambs to detect the onset of the 1st oestrus, three times daily at 6 and 12 a.m., and 6 p.m. for 20 minutes. Ewe lambs being receptive for teaser and standing for mounting by the teaser were considered in oestrus. The onset of first oestrus was used as an indicator for the onset of puberty. The obtained results could be summarized as following : FIRST TRIAL: Results revealed that rbST treatment significantly (P<0.05) increased oestrus (mating) rate (40 vs. 70%) and shortened postpartum period of ewes by about one month as compared to untreated ewes. The ovarian activity after the first oestrus during the post partum period revealed that the effect of treatment on number of follicles and corpora lutea /ovary on the ovarian surface of the right and left sides was not significant although these ovarian structures were numerous on the ovaries of treated than control group.Ewes treated with rbST showed significantly increased lambing rate of ewes based on number of treated or mated ewes (30 and 75 vs. 60 and 85.7%). SECOND TRIAL: Ejaculate volume and percentages of initial gross motility, sperm livability and sperm abnormality were affected significantly by rbST treatment. However, sperm cell concentration was not affected by rbST treatment. Semen evaluation of the 1st ejaculate of ram lambs show that all physical semen characteristics including ejaculate volume as well as initial motility, livability and normality of spermatozoa in semen of ram lambs in treated group was significantly higher than those of that in the control group. However, sperm cell concentration did not differ significantly in treated from control group. THIRD TRIAL: Ewe lambs were significantly heavier in treated than in control group only during the interval from the 4th to 7th week of suckling period. Live body weight of ewe lambs at puberty was about 36.0 kg, although age at puberty was significantly younger by about two months in treated than in control ewe lambs (240.6 vs. 300.3 days). Therefore, the current study concluded that rbST treatment (160 mg/ewe at 14-day interval) during pre- and post-partum period improved productive (live body weight and milk production) and reproductive performance (estrous and lambing rates) of crossbred ewes (1/2 Finnish Landrace x 1/2 Rahmani). In addition, improved performance and puberty characteristics of ewe and ram lambs.