الفهرس 
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Abstract
1-The present study was carried out during the period from January, 1993 to April, 1995 on twenty female balady goats. from the period from January, 1993 till February, 1994 all females were kept non pregnant and after that all females allowed to mated by a fertile buck and get kidding at different seasons of the year.
2-The obtained results came as follows.
A - Clinical observations :
a-Signs of oestrus :
Does in estrus exhibited anxiety increased frequency of bleating and urination and redness oedema of valva. In absence of buck, does showed mutual mounting with each other. In the presence of buck, does showed great interest to buck and the amount of vaginal discharge were in copious amount.
b-Frequency and length of oestrous cycle :
The present results revealed that, oestrus occurred all over the year and respond more to warmer temperature and high humidity but not to day length. The shortest length of oestrous cycle (less than 16 days) was detected at the beginning of each season and the frequency of it was higher in spring in comparison to other seasons. The longest oestrous cycle (more than 25 days) was also detected in spring in comparison to other seasons. The normal length (16 - 25 days) of oestrous cycle was higher in summer followed by that detected in autumn, winter and spring. C- Duration of heat :
A significant variation in the duration of heat during different months of the year. The shortest duration was observed during January (38.4 ± 0.68 hours) and the longest duration was observed in June (52.63 ± 0.77 hours).
d-Vaginal smears during oestrous cycle :
The cells of vaginal cytology were classified into small cells (15 -26 M), medium cells (26 - 36 M) and large cellsl (40 - 50 M). The number of large cells was higher during estrus (66.6%) and decreased sharply during post oestrus phases. The small cells was higher during diestrus phase (70%). There were a slight fluctuation in the number of medium cells throughout the cycle.
e-Hormonal profiles during oestrous cycle :
1-Progesterone :
The highest level of progesterone was detected at diestrus phase during winter (4. 700 ± 0.990 ng /ml), summer (3.633 ± 0.878 ng /m1); autumn (3.44 ± 0.990 ng / ml) and spring (2.447 ± 0.856 ng / ml) respectively. Followed by that observed in other phases of oestrous cycle in different seasons.
There was a non significant variation in progesterone level among different seasons in each phases of the cycle.
2-Oestradiol - 17 13 :
The highest level of oestradiol - 17P was detected at estrus in winter (50.597 ± 10.398 pg / ml), summer (37.272 ± 8.236 pg / ml), autumn (32.103 ± 7.787 pg / ml) and spring (29.452 ± 5.623 pg / ml) respectively. There was no significant variation in oestradiol level among different seasons in each phases of the cycle.
F- Changes in the plasma macroelements during oestrous cycle :
In all seasons the highest level of calcium, inorganic phosphonis and magnesium was observed during estrus & proestrus phase followed by that observed in other phases of the cycle. The highest level of calcium (2.574 ± 0.21 mmol/L), inorganic phosphorus (1.905 ± 0.006 mmol/L) and magnesium (0.938 ± 0.005 mmol /L) was detected during estrus in winter in comparison to other phases in different seasons of the year.
g- Vaginal smears during gestation period :
Small cells were found to be the most predominant type during different months of gestation reached incidence ranged between 79-91.3/0. The large cells showed a lower incidence ranged between 1.15 - 2.36%. The medium cells accounted for a range between 6.64 - 19.13%.
h - Signs of kidding :
The signs of kidding was observed in few does and include restless ness, frequent lied down and get up, pawing of the ground and bleating.
I- Kidding interval, first post - partum heat and conception rate.
The longest kidding interval was recorded in goats that get birth in spring (189.5 ± 1.874 days) and autumn (183.25 ± 1.25 days). The shortest period was observed in does that get birth during summer
Regarding conception rate, there was no significant variation among different seasons.
J - Hormonal profile during pregnancy, parturition and post - partum period :
1-Progesterone :
Plasma progesterone increased gradually and steadily with the advancement of pregnancy reached its maximum level at day 120 of gestation in does that get birth in spring.
2-Oestradial - 17 13 :
Plasma estrogen level increased with the advancement of pregnancy period reached its maximum values at day of birth in spring.
The season of kidding had no effect on either progesterone or oestradiol during pregnancy, parturition and post - partum period. The variation in hormonal levels was attributed to the effect of number of foeti on both progesterone and oestradiol.