No description available.

Thesis (doctoral)--Universität Hamburg, 1977.

No description available.

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No description available.

Changes in follicular dynamics were monitored in forty-four Brahman multiparous (n=30) and primiparous (n=14) cows randomly assigned to control (n=22) and once-daily suckling (n=22) treatments. Daily transrectal ultrasonography images were taken from d 21 through 88 post-calving or detection of first estrus. Suckling treatment was introduced on d 28 post-calving. Follicular waves were profiled and characterized by development and regression of a variable number of small and medium sized (2-9 mm) follicles before one of the follicles differentiated and became the dominant follicle. Primiparous cows had 34% more (P<0.04) follicular waves (4.8 + 0.6) than did the multiparous cows (3.1 + 0.4) prior to first ovulation (FO). Once-daily suckled multiparous cows had 37% fewer (P<0.03) follicular waves (2.4 + 0.5) prior to FO than controls. Interval from calving to FO was reduced (P < 0.05) by an average of 12 d by once-daily suckling in multiparous cows. Primiparous cows developed 30% more (P<0.02) dominant follicles (6.3 + 0.6) from d 21 to estrus than did the multiparous cows (4.3 + 0.4). Ovulation before d 88 occurred in 42 of 44 (95%) cows. Behavioral estrus was not detected in 40 of 42 (95%) cows at FO. The length of the subsequent estrous cycle was short (<17 days) in 39 of 42 (93%) cows. We can conclude from these data that ovarian function is resumed shortly after parturition and ovulation of a dominant follicle ends postpartum anestrous. Primiparous cows experienced more follicular waves and therefore grew more dominant follicles prior to first estrus. Once-daily suckling hastened return to estrus and reduced the number of follicular waves prior to first post-partum estrus in multiparous cows. The incidence of first ovulation being associated with behavioral estrus was low. Short cycles followed first ovulation. It appears obligatory that postpartum Brahman cows experience a silent ovulation with formation of functional luteal tissue prior to resumption of normal estrous cyclicity.

Changes in follicular dynamics were monitored in forty-four Brahman multiparous (n=30) and primiparous (n=14) cows randomly assigned to control (n=22) and once-daily suckling (n=22) treatments. Daily transrectal ultrasonography images were taken from d 21 through 88 post-calving or detection of first estrus. Suckling treatment was introduced on d 28 post-calving. Follicular waves were profiled and characterized by development and regression of a variable number of small and medium sized (2-9 mm) follicles before one of the follicles differentiated and became the dominant follicle. Primiparous cows had 34% more (P<0.04) follicular waves (4.8 + 0.6) than did the multiparous cows (3.1 + 0.4) prior to first ovulation (FO). Once-daily suckled multiparous cows had 37% fewer (P<0.03) follicular waves (2.4 + 0.5) prior to FO than controls. Interval from calving to FO was reduced (P < 0.05) by an average of 12 d by once-daily suckling in multiparous cows. Primiparous cows developed 30% more (P<0.02) dominant follicles (6.3 + 0.6) from d 21 to estrus than did the multiparous cows (4.3 + 0.4). Ovulation before d 88 occurred in 42 of 44 (95%) cows. Behavioral estrus was not detected in 40 of 42 (95%) cows at FO. The length of the subsequent estrous cycle was short (<17 days) in 39 of 42 (93%) cows. We can conclude from these data that ovarian function is resumed shortly after parturition and ovulation of a dominant follicle ends postpartum anestrous. Primiparous cows experienced more follicular waves and therefore grew more dominant follicles prior to first estrus. Once-daily suckling hastened return to estrus and reduced the number of follicular waves prior to first post-partum estrus in multiparous cows. The incidence of first ovulation being associated with behavioral estrus was low. Short cycles followed first ovulation. It appears obligatory that postpartum Brahman cows experience a silent ovulation with formation of functional luteal tissue prior to resumption of normal estrous cyclicity.

Thesis (Ph. D.)--Virginia Commonwealth University, 2009. / Prepared for: Dept. of Microbiology and Immunology. Bibliography: leaves 213 - 235. Available online via the internet.

Ovarian steroids assist in the development of the follicle and its enclosed oocyte as well as prepare the maternal environment for pregnancy. The objective of experiment 1 was to elucidate the differences between dominant follicles of each follicular wave in terms of intraollicular concentration of steroids after 4 d of dominance. Differences in blood perfusion between the dominant follicle of the first and second non-ovulatory wave were also examined. Follicular waves were monitored daily via ultrasonography from emergence to aspiration of the dominant follicle. It was determined that although the dominant follicles aspirated from ovulatory waves possessed a greater concentration of estradiol and a greater ratio of estradiol to progesterone, there was no difference in concentrations of steroid hormones or the ratio of estradiol to progesterone between dominant follicles collected from non-ovulatory waves and ovulatory waves. In a subset of cows, blood perfusion tended to be greater in dominant follicles that developed during the second non-ovulatory wave. The objective of experiment 2 was to determine whether or not the follicular wave had an effect on diameter of the ovulatory follicle, thickness of the endometrium, or subsequent pregnancy rates. Estrus was synchronized in females in such a way that females would ovulate the dominant follicle of the first or second follicular wave at timed artificial insemination. Diameter of the ovulatory follicle and endometrial thickness were not different between treatments; however, increased pregnancy rates were observed in heifers that ovulated the dominant follicle of the second follicular wave. There was no effect of follicular wave on pregnancy rates in cows. In conclusion, the role of follicular wave on the dominant follicle, maternal environment, and subsequent pregnancy rates is not fully understood. Additional experiments need to be conducted to further elucidate the differences in developmental potential of the oocyte and maternal environment when the dominant follicle of the first and second wave are destined to become the ovulatory follicle at timed insemination.