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Journal of Embryo Transfer 2012; 27(4): 237-243

Published online December 31, 2012

## Relationship between Estrous Expression Rate, BCS and Transferable Embryos in Holstein Donor Cows

Son, Jun-Kyu, Jung, Yeon-Sub, Cho, Sang-Rae, Baek, Kwang-Soo, Yoon, Ho-Beak, Lim, Hyun-Joo, Kwon, Eung-Gi, Kim, Sang-Bum, Choe, Changyong

Dairy Science Division, National Institute of Animal Science, RDA, CheonAn 331-801, Korea, Subtropical Animal Experiment Station, National Institute of Animal Science, RDA, JeJu 690-150, Korea

### Abstract

This research was investigated the relationship between the number of the transferable embryos and estrus expression rate, BCS (Body Condition Score), which affect the nutritional state of the cow, in Holstein donor cows. CIDRs were inserted into the vaginas of twenty two head of Holstein cows, regardless of estrous cycle. Superovulation was induced using folliclar stimulating hormone (FSH). For artificial insemination, donor cows were injected with $PGF_{2{alpha}}$ and estrus was checked about 48 hours after the injection. Then they were treated with 4 straws of semen 3 times, with 12-hour intervals. Embryos were collected by a non-surgical method 7 days after the first artificial insemination. When BCS was $$leq_-$$2.5, the total number of collected ova was 7.3 + 1.9, which is significantly lower (p<0.05) than the numbers 15.4 + 2.8 and 15.4 + 2.1 that were obtained when BCSs were 2.75 and $$geq_-$$3.0, respectively. Whereas the numbers of transferable embryos were 5.2 + 1.4 when BCS was $$leq_-$$2.5, which was smaller than the numbers 6.0 + 2.1 and 8.5 + 1.8 that were obtained when BCSs were 2.75 and $$geq_-$$3.0, respectively; however, the differences were not significant. As for estrus induction rate, the cow groups whose BCSs were 2.75 and $$geq_-$$3.0 showed 100.0% and 95.0%, respectively. Whereas the cow group whose BCS was $$leq_-$$2.5 showed 57.1%, and the differences were significant (p< 0.05). As for estrous expression rate, the cow groups whose BCSs were $$leq_-$$2.5, 2.75 and $$geq_-$$3.0 showed 100.0%, 100.0% and 85.7%, respectively; however, the differences were not significant. According to the result of this research, it is considered that the total number of collected ova and the number of transferable embryos will be affected by the nutritional state before and after in vivo embryo production and superovulation treatment, and that although the mechanism is not clear, poor stockbreeding management and nutritional level would cause the decrease of ovum recovery rate and the number of transferable embryos in high-producing cows. On the other hand, diverse researches on the superovulation treatment method that is suitable for high-producing Holstein donor cows would contribute to preventing ovarian cyclicity disorder, as well as to the early multiplication of cows with superior genes by increasing the utilization value of donor cows.

Keywords: Holstein donors, transferable embryo, BCS, estrus expression

### Article

Journal of Embryo Transfer 2012; 27(4): 237-243

Published online December 31, 2012

## Relationship between Estrous Expression Rate, BCS and Transferable Embryos in Holstein Donor Cows

Son, Jun-Kyu, Jung, Yeon-Sub, Cho, Sang-Rae, Baek, Kwang-Soo, Yoon, Ho-Beak, Lim, Hyun-Joo, Kwon, Eung-Gi, Kim, Sang-Bum, Choe, Changyong

Dairy Science Division, National Institute of Animal Science, RDA, CheonAn 331-801, Korea, Subtropical Animal Experiment Station, National Institute of Animal Science, RDA, JeJu 690-150, Korea

### Abstract

This research was investigated the relationship between the number of the transferable embryos and estrus expression rate, BCS (Body Condition Score), which affect the nutritional state of the cow, in Holstein donor cows. CIDRs were inserted into the vaginas of twenty two head of Holstein cows, regardless of estrous cycle. Superovulation was induced using folliclar stimulating hormone (FSH). For artificial insemination, donor cows were injected with $PGF_{2{alpha}}$ and estrus was checked about 48 hours after the injection. Then they were treated with 4 straws of semen 3 times, with 12-hour intervals. Embryos were collected by a non-surgical method 7 days after the first artificial insemination. When BCS was $$leq_-$$2.5, the total number of collected ova was 7.3 + 1.9, which is significantly lower (p<0.05) than the numbers 15.4 + 2.8 and 15.4 + 2.1 that were obtained when BCSs were 2.75 and $$geq_-$$3.0, respectively. Whereas the numbers of transferable embryos were 5.2 + 1.4 when BCS was $$leq_-$$2.5, which was smaller than the numbers 6.0 + 2.1 and 8.5 + 1.8 that were obtained when BCSs were 2.75 and $$geq_-$$3.0, respectively; however, the differences were not significant. As for estrus induction rate, the cow groups whose BCSs were 2.75 and $$geq_-$$3.0 showed 100.0% and 95.0%, respectively. Whereas the cow group whose BCS was $$leq_-$$2.5 showed 57.1%, and the differences were significant (p< 0.05). As for estrous expression rate, the cow groups whose BCSs were $$leq_-$$2.5, 2.75 and $$geq_-$$3.0 showed 100.0%, 100.0% and 85.7%, respectively; however, the differences were not significant. According to the result of this research, it is considered that the total number of collected ova and the number of transferable embryos will be affected by the nutritional state before and after in vivo embryo production and superovulation treatment, and that although the mechanism is not clear, poor stockbreeding management and nutritional level would cause the decrease of ovum recovery rate and the number of transferable embryos in high-producing cows. On the other hand, diverse researches on the superovulation treatment method that is suitable for high-producing Holstein donor cows would contribute to preventing ovarian cyclicity disorder, as well as to the early multiplication of cows with superior genes by increasing the utilization value of donor cows.

Keywords: Holstein donors, transferable embryo, BCS, estrus expression

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