Recent advances in ovulation synchronization and superovulation in ...

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Abstracts. II International Symposium on Animal Biology of Reproduction, Nov. 19-22, 2008, São Paulo, SP, Brazil. Age effects on follicle and hormone dynamics in mares J.C.F. Jacob 1 , M.O. Gastal 1 , E.L. Gastal 2 , M.A. Beg 2 , M.A.R. Siddiqui 1 , O.J. Ginther 1,2 1 Eutheria Foundation, Cross Plains, WI 53528, USA; 2 Department of Pathobiological Sciences, University of Wisconsin, Madison, WI 53706, USA. Introduction The striking similarities between mares and women in follicle dynamics and hormonal changes during the interovulatory interval (IOI; 1,2) have provided encouragement for the potential use of the mare as a relevant experimental model for the study of folliculogenesis and reproductive aging in women (3). The objectives of the present studies during the estrous cycle in mares were to characterize and compare age groups for follicle development; systemic concentrations of FSH, LH, estradiol, and progesterone; concentrations of preovulatory follicular-fluid hormones and factors; B-mode and color-Doppler characteristics of the follicle wall; and preovulatory oocyte characteristics. Materials and Methods Young (5 to 6 yr), intermediate (10 to 14 yr), and old (≥18 yr) age groups of mares separated by 4 yr were used (n = 14 to 16 IOIs/group) in experiments 1 and 3. In experiment 2, the age groups were continuous and were defined as young (3 to 7 yr, n = 11), intermediate (8 to 17 yr, n = 23), and old (≥18 yr, n = 10). None of the old mares were senescent or approaching senescence (4). In experiment 1, transrectal B-mode ultrasonographic examinations and blood sampling were done daily to encompass two consecutive IOIs. In experiment 2, mares were treated with 2500 iu of hCG when the largest follicle was ≥32 mm (Hour 0), and follicular fluid and the oocyte were collected at Hour 30 by transvaginal ultrasound-guided aspiration. Only mares with undetected plasma hCG antibodies at Hour 0 were used. At Hours 0 and 30, diameter of the follicle was measured, blood samples were collected, and the follicle wall was examined by Doppler ultrasonography (5). In Experiment 3, the induction of an ovulatory wave with prostaglandin F2α treatment and ablation of follicles ≥6 mm on Day 10 was used and daily ultrasonographic examinations and blood collection were performed. Results and Discussion In experiment 1, the IOI was one-day longer (P < 0.05) in the old group in association with a slower (P < 0.05) growth rate of the ovulatory follicle. The old group had diminished follicle activity, as indicated by significantly (P < 0.05) smaller and fewer follicles. Concentrations of FSH did not differ among age groups, except that the maximum concentration was greater (P < 0.05) in the old group. Concentrations of LH were greater (P < 0.0001) in the young group throughout the ovulatory LH surge and may have played a role in a shorter (P < 0.05) interval from maximum diameter of the preovulatory follicle to ovulation. Maximum circulating concentration of estradiol during the preovulatory surge was greatest (P < 0.05) in the young group. In experiment 2, no age effect was detected on oocyte status (meiotic stage, spindle orientation and quality, and microfilament content). Concentrations of ovarian steroids in the preovulatory follicular fluid were not affected by mare age, but the concentration of free IGF1 was greater (P < 0.05) in the old group. In experiment 3, during the common-growth phase (Days 12 to 17) of induced waves, diameter of the future ovulatory follicle was not different among ages, but the young group had more (P < 0.05) follicles that reached ≥10 mm. Concentrations of LH increased in all age groups during Days 12 to 17, but were greatest (P < 0.002) in the young group and continued to be greater (P < 0.0001) throughout the ovulatory LH surge. During several days before Day –1, there were no agerelated effects on systemic estradiol concentrations, diameter of the preovulatory follicle, or B-mode echotexture or color-Doppler signals of blood flow in the follicle wall. The present studies indicate the importance of the mare as a comparative research model for age effects, for consideration of age as a potential confounding factor in equine research protocols, and for consideration of age in development of theriogenology programs (e.g., optimal time of breeding and superovulation regimes). References (1) Ginther OJ, Gastal EL, Gastal MO, Bergfelt DR, Baerwald AR, Pierson RA. 2004. Biol Reprod, 71:1195-1201; (2) Ginther OJ, Beg MA, Gastal EL, Gastal MO, Baerwald AR, Pierson RA. 2005. Reproduction, 130:379-388; (3) Carnevale EM. 2008. Theriogenology, 69:23-30; (4) Carnevale EM, Bergfelt DR, Ginther OJ. 1994. Anim Reprod Sci, 35:231-246; (5) Gastal EL, Gastal MO, Ginther OJ. 2006. Reproduction, 131:699-709. E-mail: juliorep@ufrrj.br Anim. Reprod., v.6, n.1, p.209, Jan./Mar. 2009 209
Abstracts. II International Symposium on Animal Biology of Reproduction, Nov. 19-22, 2008, São Paulo, SP, Brazil. Ovarian follicular dynamics and plasma progesterone concentration and blood metabolites in Alpine breed goats, fed urea in the diet 210 C.A.A. Torres 1 , N.G. Alves 2 , E.A.M. Amorim 3 , L.G.B. Siqueira 4 , L.S. Amorim 3 1 Animal Science Department, CCA/UFV, Viçosa, Minas Gerais, Brazil, 36570-000. 2 Animal Science Department, CCA/UFLA, Lavras, Minas Gerais, Brazil. 3 Postdoctoral Student, UFV. 4 Graduate Student, CCA/UFV. Introduction Ultrasonographic examination of goats ovaries showed estrous cycles with an average of four follicular waves, ranging from two to six (1). Increasing the percentage of ruminal degradable protein in the diet from 11.1 to 15.7 % reduced the number of ovarian follicles of Holstein cows in the post-partum (2). The ammonia or urea excess can alter the hypothalamic-hypophyseal-gonad axis, decreasing the amplitude and the frequency of luteinizing hormone pulses, with the consequent reduction of progesterone (P4) secretion and, ultimately, the fertility (3). The objective was to study follicular dynamics in goats fed diets containing increasing concentrations of urea. Materials and Methods Twenty nine goats were randomly assigned to four treatments that received 0.0% (T1 - Controls, n = 7), 0.73% (T2, n = 7), 1.46% (T3, n = 7) and 2.24% of urea in the dry matter of the diet (T4, n = 8). The ovarian activity was monitored daily by transrectal ultrasonography during one, two or three consecutive interovulatory periods (1). Colorimetric enzyme assays were used to measure concentrations of urea and glucose in blood samples of all goats collected weekly. Blood plasma P4 concentrations were measured by solid phase radioimmunoassay (RIA) in samples collected on days 3, 7, 11, 15 and 19 after the estrus in goats that showed cycles of normal length. Results and Discussion From the 47 estrous cycles evaluated, 59.57, 14.89 and 25.53% were of normal, short and long length (17 to 25; 25 days), respectively. The normal length estrous cycles had two (n=6), three (n = 13), four (n = 8) and five (n=1) follicular waves. The short and the long length had one and two to 9 follicular waves, respectively. The animals plasma urea and glucose concentration did not differ among the treatments or weeks of collection. A quadratic effect of urea concentration in the diets on plasma P4 concentration at estrus day (Ŷ = 0.07+0.19U- 0.07*U 2 , r 2 = 0.96, P < 0.05) and on day 11 after estrus (Ŷ = 7.16+2.93U-1.54**U 2 , r 2 =0.99, P < 0.01) was observed. The highest plasma P4 concentration occurred with the intake of 1.36 and 0.95% of urea in the diets, respectively. At estrus and 11 days after, the addition of urea to the diet higher than ones used reduced the plasma P4 concentrations. On day 15 after estrus, the plasma P4 concentration was negatively and linearly associated with the proportion of urea in the diets (Ŷ = 8.29-0.98*U, r 2 = 0.58, P < 0.05). It is concluded that the interestrus and interovulatory periods, the luteal and follicular phase length and the ovarian follicular dynamics of non-lactating Alpine goats were not affected by the urea concentration up to 2.24% in the diet, but did affect the plasma progesterone concentrations. References (1) Ginther OJ, Kot K. 1994. Theriogenology, 42:987-1001; (2) Garcia-Bojalil CM, Staples CR, et al. 1998. J Dairy Sci, 81:1385-1395; (3) Kaur H, Arora SP. 1995. Nutr Res Rev, 8:121-136. Financial support: FAPEMIG and CNPq. E-mail: ctorres@ufv.br Anim. Reprod., v.6, n.1, p.210, Jan./Mar. 2009
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