The Thai Journal of Veterinary Medicine


The objective of this study was to characterize the patterns of ovarian follicular waves, and FSH and P4concentration during estrous cycle in Thai native cattle (Bos indicus). Transrectal ultrasound examination of ovarieswas performed daily using a 7.5 MHz transducer and blood samples were collected after the ultrasound examinationduring May to August, 2010. There were 1-, 2- or 3-follicular waves per cycle in heifers, and 1-, 2-, 3- or 4-follicularwaves per cycle in cows. Moreover, in cows, only one cycle exhibited 4-follicular wave pattern. The majority of TNCcows (82.76%) exhibited a 3-follicular wave pattern, whereas the majority of heifers exhibited 2-(38.10%) and 3-(47.62%) follicular wave patterns, respectively. The numbers of follicles per wave were 6.67±0.69, 7.71±0.45, and6.29±0.45 in heifers and 4.50±0.85, 4.00±0.85, 4.82±0.29, and 5.00±1.20 in cows, respectively. The length of estrous cyclewas 9.33±0.79, 15.13±0.48, and 18.57±0.51 days in heifers and 10.50±0.96, 15.50±1.46, 21.63±0.51, and 25.00±1.36 days incows. The maximum diameters of dominant ovulatory follicles in heifers were 12.13±0.62, 11.31±0.38, and 11.28±0.34and in cows 12.65±0.76, 12.45±0.76, 12.82±0.22, and 12.80±1.08 mm. The growth rates were 1.17±0.14, 1.12±0.08, and1.16±0.07 and 1.16±0.17, 1.34±0.17, 1.16±0.05 and 1.29±0.24 mm/day in heifers that had 1-, 2-, or 3- follicular wavesand cows that had 1-, 2-, 3-, or 4-follicular waves, respectively. The greater numbers of small follicles emerged morein heifers than in cows (p<0.05), while the duration of the dominant ovulatory follicle was longer in cows than inheifers (p<0.05). The plasma FSH concentrations slightly increased on days 0-1, 6-7, 13-14, and 18 of the estrous cycle,then the wave emerged on the next day. Plasma P4 concentrations slightly increased on days 5-6 and remained high3-5 days before ovulation.In conclusion, the ovarian follicular dynamic in Thai native cattle developed into 1-, 2-, 3- or 4-follicularwaves. In cows 3-follicle waves were mostly found whereas in heifers 2- and 3- follicular waves were mostly found.The duration of estrous cycle correlated to the number of follicular wave. The waves of follicular development wereconsistent with the increase in amount of FSH. Moreover, when the level of P4 decreased, the largest follicle usuallyunderwent ovulation. The results revealed differences in ovarian follicular dynamics, and in plasma concentrations ofFSH and P4, which may account for the differences in the characteristics of ovarian follicular development betweenheifers and cows of Thai native cattle.

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