Ovarian follicular Dynamics, Superovulatory Response, and In Vivo Embryo Production Potential of Boran (Bos indicus) and Boran *Holstein Cross Cattle in Ethiopia
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2016-06
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Addis Ababauniversity
Abstract
Boran (27) and Boran*Holstein crossbred (26) cows were used to study the characteristics of ovarian follicular dynamics, superovulatory response and embryo production potential. Follicular population and growth, CL number and size were monitored by ultrasonography for 61 days. Ovulation or formation of CL was used as a reference to compute the number of follicular waves and the inter-ovulatory-interval. Serum progesterone was determined every other day by immunoassay. Cows were superovullated with a combination of CIDR implant for 7days and three doses of FSH (300, 250 and 200IU), administered in a divided decreasing morning and afternoon doses over 4 days. Prostaglandin was injected on Day 6 of CIDR implantation. Cows were inseminated twice based on manifestation of standing heat. Time to estrus, duration of estrus, and CL count were used to determine superovulatory response. Embryos were flushed on Day 16/17 by non-surgical closed gravitational method. Recovered embryos/UFOs were evaluated for development stage, and quality grade. Viable embryos at stage 4-7 with quality grade 1-2 were separately loaded on to a 0.25ml straw and stored in liquid nitrogen. Some embryos (~12%) were fresh transferred to synchronized recipients. Frozen embryos were thawed and transferred to warmed slide for post thawing microscopic evaluation. Viability test was performed by culturing embryos in TCM 199 containing 10% BSA at 370C for 24 hours. The overall mean Inter-ovulatory-interval was 19.8±0.21 days and breed difference was not significant. All Boran and 56.2% of the Boran*Holstein crossbred cows had two follicular waves/cycle with a significant (P=0.001) breed difference. The mean Inter-ovulatory-interval for the cows with two and three waves/cycle was 19.48±0.94 and 20.86±2.14 days, respectively. The mean serum P4 level in Boran and Boran*Holstein cross cows were 2.01ηg/ml and 0.88 ηg/ml, respectively, and breed difference was significant (P=0.001). The total CL count was significantly higher (p=0.01) in Boran (10.1CL/cow/cycle) than Boran x Holstein crossbred cows (7.2CL/cow/cycle). A mean number of 4.1 and 2.67embryos‟/cow were flushed from Boran and Boran*Holstein crosses, respectively. The average number of transferable embryos/ cow was 3.8±0.57 and 2.67±0.99 in Boran and Boran*Holstein crosses, respectively. A significantly higher (p= 0.001) number of UFOs were collected from Boran cows (8.17±1.82). In total, 94% of the embryos were at stage 4 while 88.6% of the embryos were quality grade 2. The viability test confirmed development in 24% and 40% of the incubated Boran and Boran*Holstein
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embryos, respectively. Boran breeds showed a relatively better potential for application of embryo technology in terms of ovarian follicular growth, superovulatory response, and embryo production. The uniformity of waves of follicular growth in each cycle is an additional virtue of the Borans for application of biotechnology tools such as estrous synchronization and superovulation for breed improvement or conservation.
Key words: ovarian follicular dynamics, follicular waves, superovulatory response, embryo
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Keywords
ovarian follicular dynamics, follicular waves, superovulatory response, embryo