Advancement of ovulation and oestrus after temporary calf removal and FSH supplementation in postpartum beef cows

Rivera, Gonzalo; Alberio, R. H.; Callejas, S.; Doray, J.M.

doi:10.1016/0378-4320(94)90049-3

Cited by 5 publications

(2 citation statements)

References 40 publications

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“…It should be mentioned that this selection may occur through a passive mechanism, wherein the largest follicle indirectly inhibits the growth of the immature follicles through a reduction of follicle stimulating hormone (FSH), to levels below those necessary for the maintenance of the other follicles, or in an active manner, where the dominant follicle inhibits the growth of the others by secreting substances that reduce the sensitivity of the subordinates to FSH, as reported by Driancourt (1991). It is likely that a slight increase in the concentration of FSH occurred 1 or 2 days prior to the emergences of the waves, as observed by Adams et al (1992) and Bodensteiner et al (1996), which demonstrates the importance of FSH for the occurrence of follicular waves, as also mentioned by Mihm et al (1997), Ginther et al (1998), Bodensteiner et al (1996), Fortune (1993) and Rivera et al (1994). After the transitory elevation of FSH, a decrease in the levels of this hormone occurs.…”

Section: Discussionmentioning

confidence: 62%

Ovarian Follicular Dynamics of five-eighths Girolando Cows

Filho¹,

Oliveira²,

Caldas³

et al. 2001

Reprod Domest Anim

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The objective of this study was to examine the follicular dynamics of five-eighths Girolando cows by observing the number of follicular development waves, days of emergence of those waves, diameters of the dominant and largest subordinate follicles and the processes of follicular selection and dominance. Ovarian follicle dynamics were monitored for 24 oestrous cycles in 12 cows, of 4 to 10 years of age, presenting regular oestrous cycles and with body scores between 3 and 4. Ovaries were observed daily for two consecutive oestrous cycles and follicles were measured with ultrasonographic equipment. The dominant follicle was considered to be that which presented a diameter > or = 10 mm for three consecutive days and on the day of wave emergence, when a group of follicles measuring 3-5 mm in diameter would appear. Of the 24 cycles monitored, 62.5% presented two waves of follicular development and 37.5% presented three waves. The cycles presenting two waves had an average duration of 20 days, with the emergence of the waves on days 1 and 9, whereas the cycles presenting three waves had an average duration of 22 days, with emergences on days 1, 10 and 16. For cycles with two waves, both the first and second dominant follicles reached an average size of 13.8 mm, with the first regressing on day 10 and the second ovulating around day 20. For cycles with three waves, the dominant follicles of the first and second waves reached maximum diameters of 11.8 and 12 mm, respectively, with the first regressing on day 11 and the second regressing on day 17. The third dominant follicle reached a maximum diameter of 12.4 mm on day 20, and ovulated on day 22. These results lead to the conclusion that the follicular dynamics of five-eighths Girolando cows are characterized by the presence of two to three waves of follicular growth.

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Section: Discussionmentioning

confidence: 62%

Ovarian Follicular Dynamics of five-eighths Girolando Cows

Filho¹,

Oliveira²,

Caldas³

et al. 2001

Reprod Domest Anim

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“…In cattle, short-term calf removal increased conception in synchronized lactating females (Smith et al, 1979;Kiser et al, 1980;Yelich et al, 1995). However, the effect of temporary calf removal on the duration of anestrus is variable (Wright et al, 1987;Rivera et al, 1994). Body-condition score (Alberio et al, 1984), duration of calf removal (Shively and Williams, 1989), and interval from calving to calf removal (Bonavera et al, 1990) all may combine to influence the outcome from this treatment.…”

Section: Temporary Lamb Removalmentioning

confidence: 99%

Effects of ovulation of aged follicles, pregnancy diagnosis by ultrasonography, and treatments during lactation on reproduction in ewes

Wurst¹

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Ewes are polyestrous and litter-bearing seasonal breeders. Although average ovulation rates are sufficient, many ovulations do not result in live offspring and ewes normally breed only once per year. As ovulation rate increases, so does the number of ovulations not represented by live births. When ultrasonographic analysis is limited to ovarian follicles that grow from 3 to 5 mm, follicular waves can be identified in sheep. In most cases, ovulatory follicle(s) develop from the ultimate follicular wave; however, ovulatory follicles can be derived from penultimate or earlier follicular waves. The relationship between lifespan of large follicles and fertility is controversial in sheep. In experiment 1, three approaches to create a model to compare fertility when ovulatory follicles developed from only the ultimate follicular wave or both ultimate and penultimate waves were tested. Ewes were treated on d 10 or 11 with 50 μg of GnRH i.m., the largest follicle(s) (≥ 4 mm) on each ovary were electrocauterized, or ewes were treated with 50 µg estradiol benzoate and 50 mg progesterone or 100 µg estradiol benzoate and 50 mg progesterone in attempts to induce follicular regression or luteinization. Corpora lutea were counted by ultrasound 7 days following estrus in order to verify ovulation of follicles that disappeared post estrus. Pregnancy was determined and embryos were counted 20 to 30 days following estrus. Neither treatment with GnRH nor estradiol and progesterone consistently caused regression or luteinization of ovulatory-sized follicles. Follicular ablation was successful in increasing the proportion of ovulations originating from the ultimate follicular wave in Dorset/Suffolk cross ewes, but did not alter the proportions of ovulations fom different waves in Polypay ewes. Average age of the ovulatory follicle was affected only in Dorset/Suffolk cross ewes. Due to lack of treatment effects, ovulatory follicles were evaluated regardless of treatment for effects on embryonic or fetal losses. Although loss tended to differ among follicular age combinations and wave sources of ovulatory follicles within ewes, older follicles did not have worse outcomes than younger follicles. Lactating ewes have not responded to treatments for the induction of estrus that are effective in dry ewes during the anestrous season. In experiment 2, lactating anestrous ewes 26 to 71 days postpartum were treated with either 25 or 50 mg progesterone/day for five days before ram introduction (RI). Twelve hours after RI, lambs were removed from half of the ewes in each group for 72 hours. Estrous response was recorded and ewes were scanned by transrectal ultrasonography on days 8 and 35 to 45 to determine ovulation rate, and pregnancy rate and number of embryos/fetuses, respectively. Number of lambs born was recorded at lambing. No effect of lamb removal was found for any variable examined. However, the lower dosage of progesterone reduced the mean time to estrus, increased the proportion of ewes ovulating, and decreased an incredible work ethic ...

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