Physiological studies on the reproduction of sheep. " Artificial insemination and early pregnancy diagnosis in sheep"
Abstract: Mature Finn cross bred ewes and rams (Finn. X Ossimi, and Finn X Rahmani) were used in this study.
1-Experiment 1:
Five mature crossbred rams (39.2 months of age), were used for natural mating and for Artificial Insemination. Semen was collected from the rams 4 to 5 months in advance (April - May) to the time of insemination. Semen was frozen and stored until use.
All ewes (160 ewes) were subjected to estrous detection two times daily using two teaser rams starting from 2 September 1996 to 10 Oct. A total number of 128 ewes exhibited estrus. Eighty of them were synchronized for the second estrus. Animals were distributed randomly between four breeding methods. The rest (n=48 ewes) were left to show natural estrus but were bred similarly by the 4 breeding methods and fertility were tested.
Animals were bred either naturally or by A.I (Vaginal, Transcervical and Laparoscopic), to test the effect of site of semen deposition on fertility. The effect of oxytocin (10 IU into the vaginal submucosa),on ewes was tested for the cervical dilation of the transcervical inseminated ewes. Oxytocin treated ewes came in heat both by synchronization by Estrumate+PMSG and naturally.
The four methods of breeding were used to represent three sites of semen deposition in the female reproductive tract (vagina, cervix and uterus).
Insemination of synchronized ewes; by vaginal and transcervical technique were carried out at 44 and 52 hr post PG / PMSG injection using two straws of 180 x 106 total sperm / straw for each insemination.
As for laparoscopic inseminated ewes they received one straw only (180 x 106 total sperm), in one insemination, at 52 hr. post hormone injection.
Ewes naturally came in heat were checked for estrus twice daily (8 am and 4 p.m.). Those treated with vaginal and transcervical insemination were bred twice (at the onset of estrus and 12 hr later).
The laparoscopic inseminated ewes were bred once 12 hr post the onset of natural estrus.
Ewes failed to conceive after insemination from both groups (synchronized or natural heat) were reinseminated at the following estrus using the same method as in its first insemination. Similarly ewes returned to estrus after natural mating were remated.
Twenty-four hours post PG injection estrus was detected by teaser rams at 4 hr. interval and onset and duration of estrus were recorded. The ewes examined for pregnancy at different stages of gestation period using different four methods (Non-return to estrus; Progesterone level; Laparoscopyand Ultrasound).
2- Experiment 2
The aim of this experiment was to study the effect of two different levels of oxytocin, intravenously injected (10,20 IU),on cervical dilation and pregnancy rates as affected by site of semen deposition in the reproductive tract using fresh extend cooled semen.
A total number of 57 ewes exhibited estrus naturally were used for breeding. According to the onset of estrus in a sequential manner each three ewes were intravenously injected with 0, 10 and 20 IU oxytocin, respectively and inseminated 8 minutes later using fresh Tris buffered extender (5C°). Semen of second ejaculates was only used (0.8 ml, 2 x 10. motile sperm) .Semen was deposited and depth of insertion was measured.
The inseminated ewes within each group were classified according to semen deposition into 3 categories.
1- Less than 1 cm depth ,considered as vagina.
2- One cm or more ,cervical.
3- Deep inserted catheter , intrauterine.
All inseminated ewes were ultrasonically diagnosed for pregnancy 40-60 days following insemination. Depth of semen deposition and pregnancy rates were calculated for each treatment group. Chi square (x2) of independence was used to compare pregnancy rates between treatments and between site of semen deposition categories.
Results.
I Experiment 1:
1- Overall mean of time at which estrus has occurred post hormonal injection for the 60 synchronized ewes was 32.26:t 0.5 hr. with a range from 26 to 42 hr. Differences between breed groups were statistically not significant.AII PG treated animals responded by exhibiting estrus.
2- Average estrus period duration for the 60 synchronized ewes was 41.73:t 1.45 hr. with a range from 24-68 hr.
3- The overall conception rate was higher for the synchronized ewes (83.3%) than that of the natural estrus, (77.1 %) but differences were not significant.
4- Overall means of conception percentages regardless to type of cycle were 65.6,75.0,87.1and 96.8% for vaginal, trans-cervical and laparoscopic insemination methods and natural mating, respectively.
5- The inseminating catheter passed into the uterus of 4 out of 32 (12.5%) of the submucosally injected ewes with 10 IU Oxytocin.
6- A progesterone level of 1 ng/ml or higher at day 15, 16 and 17 was considered as a sign of pregnancy. Accuracy of positive response to the test was 78.7, 82.2 and 94.9 % on the three days. All ewes diagnosed as non-pregnant on any day of the test actually failed to conceive.
7 -The overall accuracy of non-returning to estrus as pregnancy diagnostic method was 91.9%.
8- Accuracy of laparoscopic pregnancy diagnosis (24-26 days post breeding) was 100% (all diagnoses were correct)
9- Accuracy of ultrasonic of positive diagnosis was 90.9% during the stage from 29 to 45 days of gestation, increased to 95.6 and 100% during the periods 46-60 and 61-88 days post insemination, respectively. For ewes diagnosed as non-pregnant, the accuracy of the test was markedly lower being 50.0, 70.6 and 80.0% during the' three stages, respectively.
10- Overall superiority of synchronized ewes (L.S.=2.3/ewe) over those with natural heat (L.S.=1.96/ewe) was 17.3% and differences were statistically significant (P<0.05).
11- Overall mean of litter size was significantly (P<0.01) higher in 1/2 F.
1/2 R group (2.57 ±0.34) than all other breed groups. Ewes of the other three groups had about similar litter size values (1.89 ± 0.11, 1.80 ±0.24 and 1.80 ±0.14 in 1/2 F. 1/2 O, 1/4 F. 3/4 R and ¼ F. % 0 ewes, respectively) .
12- Mean values of ovulation rate were 3.44, 2.08, 2.40 and 2.86 in the ½ F. ½ R., ¼ F. ¾ R., ½ F. ½ O and ¼ F. ¾ O groups, respectively. The corresponding litter size values were 3.22, 1.83, and 2.14 lambs born / ewe. Percentage of ova wastage were 6.40, 12.00, 8.33 and 25.00% in the ewes of the four breed groups, respectively.
13- All ova wastage occurred in ewes having >3 CLs (12.5% of the ova were wasted).About 41 % of ewes with >3 ovulations lost ova, while none of the ewes with single or double ova lost any ovum.
14- Overall mean of daily progesterone level during the 12th to the 17th day of pregnancy ranged from 2.62± 0.47 ng/ml on day 12 to 3.45 ±o.63 ng/ml on day
15-The overall mean value (ng/ml) of progesterone concentration was similar in ewes lambed twins and triples. Differences in level of P 4 were only significant between those lambed singles and quadrates or more.
Experiment 2:
15- The highest rate of successful penetration into the uterus (78.95 %) occurred in ewes injected with 20 IU oxytocin (group 3) followed by those treated by 10 IU oxytocin (group 2 , 68.42 % ). On the other hand, the inseminating tube failed to exceed the external oscervical of ewes in group 1 (0 IU oxytocin) .
16- The overall pregnancy rates were 63.2 , 73.7 and 84.2 % for groups 1 , 2 and 3 ,respectively.
On the light of the results of this study i.v. injection of 20 I.U.
oxytocin before insemination may be useful in dailating the ewe cervical canal and allowing deep semen depostion which in turne may increase fertility level.
Publication year 1999
Pages 120p.
Availability location مكتبة معهد بحوث الانتاج الحيوانى -شارع نادى الصيد- الدقى - الجيزة
Availability number 672
Organization Name
Country Egypt
Department Sheep and Goat Research Department
Author(s) from ARC
Agris Categories Animal physiology - Reproduction
AGROVOC
TERMS		 Artificial insemination. Copulation. Ewes. Fertility. Oxytocin. Pregnancy. Rams. Reproduction. Semen. Sheep.
Publication Type PhD Thesis
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