Peerayut Nilchuen, Sukanya Rattanatabtimtong, and Srisuwan Chomchai

pp. 679 - 683

Abstract

An experiment was conducted to investigate the effect of different doses of follicle stimulating hormone (FSH) used
in a superovulation program on numbers of corpora lutea, total ova/embryos and transferable embryos in Kamphaeng Saen
beef cattle. Cyclic cows (n=3) and heifers (n=3) of Kamphaeng Saen beef breed were assigned to two levels of FSH (200 and
250 mg. NIH-FSH-P1) in Crossover Design by which two changes over treatments were studied over two periods in all
animals. Cows and heifers were estrous synchronized by Cloprostenol (500 µg). Estrus detection was performed by teaser
bull (Day 0 = day of the onset of standing estrus). On day 9 after the onset of standing estrus, all animals were treated with
FSH twice daily in decreasing doses over 4 days. On day 3 of FSH injection, each animal was treated with Cloprostenol (500
µg). At the first standing estrus, all animals were artificially inseminated three times at 12 h intervals. Two straws of frozenthawed semen of Kamphaeng Saen bull were used per insemination. All animals were treated with gonadotropin releasing
hormone (10 µg of Buserelin) at first insemination. Numbers of corpora lutea were determined by rectal palpation and embryos
were flushed seven days after the onset of standing estrus and classified according to the development stage and quality.
The results showed that numbers of corpora lutea, percentages of total ova/embryos and percentages of transferable embryos
were not significantly different (P>0.05) between treatments (FSH: 200 versus 250 mg) in either cows or heifers.