First follicular wave pattern of Kedah-Kelantan cows stimulated with different types of gonadotropin hormone regimes for transvaginal oocyte aspiration

The aim of the study was to compare the first wave pattern of follicular development in terms of mean number of follices and follicular size of Kedah-Kelantan beef cows stimulated with four different protocols of gonadotropin hormone regime. Twenty four Kedah-Kelantan (KK) beef cows were treated with four different regimes: A) Follicle Stimulating Hormone (FSH) administered a total of 18 NIH units in a dividing dose at decreased volume twice a day for 3 consecutive days beginning on day 4 of controlled internal drug release (CIDR®) insertion, B) FSH, administered a total of 18 NIH units in a dividing dose at decreased volume twice a day for 4 consecutive days begining on day 4 of CIDR® insertion, C) Pregnant Mares’ Serum Gonadotropin administered 2500 iu intramuscularly on day 4 of CIDR insertion, and D) FSH injected a total of 18 NIH units intramuscularly in a dividing dose at decreased volume twice a day for 4 consecutive days beginning on day 9 of prostaglandin injection. Ovaries were visualized with a 7.5 MHz linear array transrectal transducer attached to a portable ultrasound scanner. In regimes A and B, a higher number of follicles was available on days 1 and 2, and on days 0 to day 2, respectively. However, the medium size follicles of regimeB and C were mostly available in greater number on day 1, and day 1 to day 2, respectively. Similarly in regime C, availability of higher number of medium follicles was on day 1 to day 2, small follicles on day 0, and total number of follicles was in greater number on day 2. While in regime D, a greater number of follicles was available on day 2. The results showed that regimes A and B had significantly higher (P<0.05) total number of follicles compared to C and D. The trend of follicular development with various types of gonadotropin hormone regimes was similar for all regimes with small follicles were in greater number at the early part of the growth phase and subsequently followed by an increase in medium and larger follicles. As a conclusion OPU could be done on day 1 for regimes A and B and day 2 for regimes C and D, or the whole duration of OPU could be conducted from day 1 to 3 after CIDR removal or the last injection of PGF for all four gonadotropin hormone regimes.