الفهرس 
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Abstract
The prese t study was designed to study the effect of dose (1500, 2000, 2500 and 3000 IU) of PMSG injection, day (10th, 12th and 14th of estrous cycle) of BMSG injection, day (5th, 6th, 7th
and 9th after the beginning of estrus) of embryo recovery and type ( natural or artificial insemination with different doses of spermatozoa ) of breeding on the on farm system of embryos transfer. The main results could be summarized as follows:-
A) Effect of dose of PMSG:
1-there was a significant increase in the number of recovered and transferred embryos and pregnancy rate (%) associated with the increase in PMSG dose from 1500 IU (1.6 + 0.2, 1.6 + 0.2 and 25.0, respectively) to 2000 IU (7.4 + 0.9, 5.4 + 0.7 and 40.7, respectively) and 2500 IU (9.8 + 0.5, 7.9 + 0.6 and 60.0 respectively), followed by a significant decrease after injection of 3000 IU (5.0 ± 0.9, 4.0 + 0.6 and 43.8, respectively).
2-The rate of’ embryo recovery appeared to be significantly higher after injection of 2500 IU (42.98%) followed by 2000 IU (32.46%) and 3000 IU (17.34%), while the lowest rate of embryo recovery was associated with injection of 1500 IU (7.02%) of PMSG.
3-Regardless of the injected dose of PMSG, morula percentage was the highest (35.09%) followed by compact morula (28.08%) and blastocyst (26.31%). The lowest rate was obtained for the hatched blastocyst (10.92%).
4-A total number of 51, 28 and 35 recovered embryos were identified to be of good, fair and bad quality, respectivly. Of these number 43, 5 and 0 cases were conceived.
5- The hgihest rate of pregnancy for recepient cows was associated with tranfer of good quality embryos (particularly morula and compact morula).
B) Effect of day of PMSG injection:
1-The number of recovered and transferred embryos and pregnancy rate appeared to be significnatly higher after injection of 2500 IU PMSG on the 12111 day (9.4 + 0.7 , 7 + 0.4 and 46.2, respectively) than that on the 10111 day (4.0 + 0.3 , 3.0 + 0.3 and 40.0, respectively) or on the 14’1’ day (2.2 + 0.6 , 1.6 + 0.5 and 25.0, respectively).
2-The rate of embryo recovery aNeared to be significantly higher after injection of PMSG on the 12111 day (60.26%) than that on the 10th and 1411’ days (25.64 and 14.10%, respectively) of the estrous cycle.
3-Regardless the effect of day of PMSG injection, the highest rate of recovery was found with morula (42.31%) followed by compact morula (26.92%) and blastocyct (20.51%). The lowest rate of recovery obtained for hatched blastocyst (10.26%).
4-A total number of 44, 18 and 16 recovered embryous were identified to be good, fair and bad quality, respectively. Of these number 23, 3 and 0 cases, respectively were conceived.
5-The highest rate of pregnancy for recepient cows being associated with transfer of good quality embryos (particularly morula and compact morula).
C) Effect of day of embryo recovery :
1- The number of recovered and transferred embryos and pregnancy rate (%) appeared to be significantly higher after recovery of embryos from the donor cows on the 611’ day (8.0 + 0.7, 6.6 + 0.5 and 48.5, respectively), 7111
day (8.5 + 0.4, 6.0 + 0.4 and 50.0, respectively) and 9th day (7.3 + 1.2, 4.3 + 0.9 and 61.5, respectively) than on the 5th day (4.0 + 0.4, 3.0 + 0.4 and
33.3, respectively) after beginning of estrus.
2-The rate of embryo recovery appeared to be higher when the embryos were collected from donors on the 6th and 7th days (35.71 and 30.36%, respectively) than on the 561 and 9th days (14.29 and 19.64%,
respectively) after onset of estrus.
3-Regardless the effect of day of embryo recovery, the highest rate of recovery came with the compacted morula (31.25%) followed by the blastocyst and morula (25.89 and 25.00%, respectively). The lowest rate of recovery was obtained with hatched blastocyst (17.86%).
4-A total number of 57, 33 and 22 recovered embryos were identified to be of good, fair and bad quality, respectively. Of these numbers, 31, 6 and 0 cases, respectively were conceived .
5-The highest pregnancy rate for recipient cows being associated with transfer of good quality embryos (particularly morula and compact
morula).
D) Effect of type of breeding:
1- the number of recovered and transferred embryos appeared to be significantly higher after the donor cows were naturally mated (12.0 + 0.6 and 5.3 + 0.2 , respectively) or artificially inseminated with 90 x 106 (10.0 + 0.6 and 8.7 + 0.9, respectively) spermatozoa than after insemination with 60 x 106 spermatozoa (3.0 + 0.3 and 1.3 + 0.3 , respectively). Meanwhile, the pregnancy rate for recipient cows appeared to be higher after transfer of embryos recovered from donors that artificially inseminated with 90 x 106 spermatozoa (54.5%) followed by those inseminated with 60 and 120 x 106 spermatozoa (50.00 and 42.30%, respectively) and those naturally bred
(43.70%) .
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SUMMARY
2- The rate of embryo recovery appeared to be higher from donors cows that naturally mated (34.00%) or artificially inseminated with 120 and 90 x 106 spermatozoa (30.00 and 27.00%, respectively) than from
donors inseminated with 60 x 106 spermatozoa (9.00%).
3-Regardless the effect of type of breeding, the highest rate of recovery came with morula (43. 14%) followed by the compact morula (32.35%) and blastocyst (18.36%). The minimum rate of recovery
was recorded for hatched blastocyst (5.88%).
4-A total number of 51.31 and 20 recovered embryos were identified to be good, fair and bad quality, respectively. Of these numbers 26, 5
and 0 cases were conceived, respectively.
5-The highest pregnancy rate for recipient cows were recorded after transfer of good quality embryos (particularly morula, compact
morula and blastocyst).
For the on farm application of embryo transfer, it could be concluded 1-For superovulation a single dose of 2500 IU, PMSG should be injected
mostly around the 12th day of the estrous cycle.
2-The largest number of embryos can be collected on the 6th, 7th days of natural service or artificial insemination.
3-Natural breeding or artificial insemination with sperm dose of 90 x 106 could be recommended to achieve high conception rate after transfer of embryos.