الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 215 |  |  |
| | | from | 215 | | |
Abstract
The present study was carried out at Sheep
Experimental Farm, Department of Animal Production,
FaCulty of Agriculture, Zagazig University (Benha
Branch). Radioimmunological assays for plasma estrogen
were performed in laboratories of the Endocrinology
Research Unit, Atomic Energy Establishment.
It was aimed to detect plasma estrogen pattern
in Ossimi sheep during different stages of estrus
cycle, pregnancy period and 60 days postpartum period
in ewes of different ages, parities and body weights.
The study was performed on 63 Ossimi ewes,
which were sUbjected to normal husbandary system
applied at the station.
Hormonal assay was carried out at different
stages of estrous cycle, at IO!!!., 40!!!., 70!!!., IOO!!!.
and 130!!!. days of pregnancy period and at lambing
day and at the 10lh, 30lh and 60th days after
parturition in ewes of different ages, parities and
body weight.
In addition assay was performed at
the same periods in ewes having different types of
birth (Single or twins) and different Sex of embryo
(male or female).
RESULTS OBTAINED COULD BB SUMMARIZED AS FOLLOWS:
1- Plasma Estrogen Level At Different Stages Of
Estrous Cycle:
1- Except
birth,
the ewe’s body weight and the type of
which showed significant (P<O.Ol) effect
on plasma estrogen level during estrous cycle,
other studied factors had no significant effect
on this trait.
2- There was’nt any significant variation in plasma
estrogen level due to estrous cycle stage.
Which may indicate the absence of the feedback
oscillation of hypothalamic- hypophyseal- ovarian
system. This may be the main physiological
reason explaining the ’relative’ low productivity
in Ossimi sheep.
3- No significant interaction effect was found
between any of the factors studied and estrous
cycle intervals.
4- Analysis of variance for the data of ewes having
irregular estrous cycle, did
significant variation in plasma
not show any
estrogen level
due to the parity number, successive estrus
phases and the interaction between them•
5- The first degree equation of regression was
(158)
not found to be the form of the best fitting
curve for predicting the level of estrogen
during estrous cycle.
6- The coefficients of correlation between plasma
estrogen level and time intervals throughout
the estrous cycle in ewes of l~, 2~,
3-rd and 4!h parities were,
0.075, 0.164, 0.109
and 0.022, respectively.
II- Plasma Estrogen Level During 130 Days Of
Pregnancy Period:
1- Any of the factors studied had significant
effect on the level of plasma estrogen level
during the pregnancy period. This indicates
that estrogen levels in plasma of the pregnant
ewes along the pregnancy period is a result
of hormonal activity of either hYPothalamus
or pituitary gland rather than any other factor.
2- Gradual and continuous rise in the level of
plasma estrogen was observed in all experimental
groups of ewes. Variation in plasma estrogen
level during various intervals of pregnancy
period Was found to be significant (P<O.OlJ
in all groups.
3- The interactions between each of the factors
studied and intervals of pregnancy period were
found to be of no significant effect on the
level of plasma estrogen.
4- The linear regression equation was found to
be the form of the best fitting curve for predicting
the level of estrogen in any date during
pregnancy.
5- The coefficients of correlation betwe”m plasma
estrogen level and time intervals throughout
the pregnancy period in ewes of nulr , first,
second, third and fourth parities were, 0.783,
0.634, 0.692, 0.581 and 0.676, resPectively.
6- Gestation period averaged 151.68 days which
was not affected by any factor studied. On
the other hand, average of birth weight of
new born lambs was found to be 3.27 kg. Partial
regression coefficient indecated that for One
day increase in gestation length, there is
an increase of 0.06 kg.
111- Plas:ma Estroqen Level Along 60 Days Of The
Postpartum Period.
1- Any of the factors studied had· significant
effect on level of plasma estrogen level along
60 days of the postpartum period.
2- In all experimental groups of ewe’s plasma
estrogen level was relatively higher at lambing
day, then gradually decreased towards the 60!!!.
day after lambing. Variations in this trait
due to the postpartum intervals of estimation
was found to be significant (P<O.Ol).
3- The interaction between each of the studied
factor and intervals of estimation was found
to have insignificant effect on the level of
plasma estrogen along the 60 days of postpartum
period.
4- The linear regression equation was fOund to
be the form of the best fitting curve for predicting
the level of estrogen in any intervals
during the postpartum period.
5- The coefficients of correlation between plasma
estrogen level and time intervals throughout
the postpartum period were -0.450, -0.504,
-0.563, -0.418 in ewes of the 1st, 2m!, 3!1!
and 4th parities, respectively.