J Yapura

Publications (3)6.18 Total impact

• Article: Lengthening the superstimulatory treatment protocol increases ovarian response and number of transferable embryos in beef cows.

  A García Guerra, A Tribulo, J Yapura, J Singh, R J Mapletoft
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  ABSTRACT: This study determined if lengthening the superstimulation protocol from 4 to 7 days would result in an increase in the superovulatory response with no adverse effects on oocyte/embryo competence in beef cows. Follicular ablation was performed, a progesterone-releasing intravaginal device (PRID) was inserted, and cows were assigned to one of two treatment groups 5 to 8 days after ovulation: Control (4 days of follicle stimulating hormone (FSH)) or Long (7 days of FSH; n=12 per group). The FSH treatments were initiated 1.5 days later (Day 0). A dose of 400 mg NIH-FSH-P1 (Folltropin-V) was distributed equally over 8 (Control) or 14 (Long) im injections at 12-h intervals. Prostaglandin F2α (PGF) was administered twice, 12 h apart, on Day 2 (Control) or Day 5 (Long), and PRID were removed 12 h after the second PGF. Both groups were given 25 mg pLH (lutropin-V) im 24 h after PRID removal and AI was done 12 and 24 h later. Ova/embryos were collected 7 days after the pLH injection. The mean (±SEM) number of ≥9 mm follicles at the time of first AI did not differ (P=0.24) between groups, but more ovulations (30.9±3.9 vs. 18.3±2.9, P=0.01) and CL (27.2±2.1 vs. 20.8±2.2, P=0.04) occurred in the Long group. A higher proportion of the ≥9 mm follicles ovulated between 12 and 36 h after pLH in the Long group (93 vs. 69%; P=0.001). Although numerically higher in the Long group, mean numbers of total ova/embryos, fertilized ova, transferable or freezable embryos did not differ. In conclusion, a lengthened superstimulatory treatment protocol resulted in more follicles acquiring the capacity to ovulate with an increased number of ovulations, and without a decrease in oocyte/embryo competence.
  Theriogenology 04/2012; 78(2):353-60. · 1.96 Impact Factor
• Article: 224 effect of lengthening the superstimulatory treatment protocol on the ovarian response and numbers of transferable embryos in beef cows.

  A Garcia Guerra, A Tribulo, J Yapura, J Singh, R J Mapletoft
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  ABSTRACT: The present study was designed to test the hypothesis that an increase in the length of exposure of ovulatory follicles to progesterone and FSH during ovarian superstimulation will increase the number of ovulations and viable embryos in cattle. Twenty-four beef cows were initially subjected to follicle ablation at random stages of the oestrous cycle to determine the number of follicles at wave emergence; cows with comparable numbers of follicles were randomly allocated to groups by replicate. A single dose of prostaglandin F(2α) (PGF; Estroplan, Vétoquinol, QC, Canada) was given IM 7 to 9 days after follicle ablation and daily ultrasound examinations were performed to detect ovulation. Follicular ablation of all follicles ≥5mm was done 5 to 8 days after ovulation and a progesterone-releasing intravaginal device (PRID, Vétoquinol) was inserted. The Control group (n=12) was treated with 4 days of FSH and cows in the Long group (n=12) were given 7 days of FSH treatment. The FSH treatments were initiated 1.5 days after ablation (Day 0) with a total dose of 400mg of NIH-FSH-P1 (Folltropin-V; Bioniche Animal Health, Belleville ON, Canada). The total dose of FSH was distributed equally over 8 (Control) or 14 (Long) IM injections at 12-h intervals. Prostaglandin F(2α) was administered twice (at 12-h intervals) on Day 2 (Control) or Day 5 (Long) and PRID were removed 12h after the last PGF. Both groups received 25mg of porcine LH (pLH) IM (Lutropin-V; Bioniche Animal Health) 24h after PRID removal and AI with frozen-thawed semen of proven fertility was done 12 and 24h later. A third AI was done 12h later in cows with 2 or more follicles ≥9mm (12/12 and 9/12 in Control and Long groups, respectively; P=0.22). All animals were subjected to transrectal ultrasonography every other day and at the time of ova or embryo collection. Ova or embryos were collected nonsurgically 7 days after the pLH injection and evaluated following IETS guidelines. Embryos were defined as transferable (Grades 1, 2 and 3) and freezable (Grades 1 and 2). Procedure Genmod was used to compare variables between treatments and results are presented as means±SEM (Table 1). There was no significant difference in the total numbers of ova/embryos recovered, but there were more ovulations, corpora lutea (CL), fertilized ova and transferable and freezable embryos in the Long group (P<0.05). Collection efficiency (number of ova/embryos over the number of CL) was lower in the Long group (P<0.05). In summary, lengthening of the superstimulatory treatment resulted in an increased number of ovulations without a decrease in oocyte or embryo competence. Data suggest that the traditional 4-day superstimulatory treatment protocol provides inadequate time to maximize ovulatory response.
  Reproduction Fertility and Development 12/2011; 24(1):224. · 2.11 Impact Factor
• Article: 4 effect of a prolonged aromatase inhibitor treatment on pre-ovulatory ovarian follicles in cattle.

  J Yapura, J Singh, R J Mapletoft, R Pierson, D Rogan, G P Adams
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  ABSTRACT: Letrozole, a non-steroidal aromatase inhibitor, prevents the body from producing its own oestrogen. The potential use of this compound for herd synchronization is supported by previous studies in which letrozole treatment increased mean plasma LH concentrations, prolonged the period of dominance of the extant dominant follicle and delayed emergence of the next follicular wave. Heifers given a 3-day regimen of letrozole exhibited greater corpus luteum diameter indicative of a luteotrophic effect. The objective of the present study was to test the hypothesis that letrozole treatment during the development of the preovulatory follicular wave will delay ovulation. Post-pubertal beef heifers were given 2 luteolytic doses of PGF (12h apart) and monitored by ultrasonography for ovulation. Ovarian follicular wave emergence was synchronized by ultrasound-guided transvaginal follicular ablation 5 to 8 days after PGF-induced ovulation (Day -1=follicular ablation, Day 0=wave emergence) and a luteolytic dose of PGF was given 60 and 72h later. On Day 1, heifers were divided randomly into 2 groups (n=15/group) and given an intravaginal device containing 1g of letrozole or a blank device (control). The intravaginal devices were removed on Day 7, or at the time of ovulation, whichever occurred first. The ovaries were monitored by ultrasonography and a blood sample was collected daily from day of ablation to 12 days post-ovulation. Single point measurements were analysed by t-tests and serial data were analysed by analysis of variance for repeated measures. Multiple contrasts were made by Tukey's test. The interval from placement of the intravaginal device to ovulation was longer in letrozole-treated animals (6.1±0.25 vs 5.1±0.26 days, P<0.01). Compared with controls, the day-to-day diameter profile of the dominant follicle of the ovulatory wave was larger (P<0.05) and the maximum diameter greater (14.6±0.51 vs 12.4±0.53mm; P<0.01) in letrozole-treated heifers. The diameter profile of the corpus luteum formed post-letrozole treatment did not differ between groups; however, plasma P4 concentrations were higher (P<0.01) in heifers treated with letrozole. In summary, a slow-release intravaginal letrozole device delayed ovulation by 24h and induced the formation of a corpus luteum that secreted higher levels of progesterone. A slow-release intravaginal letrozole device may become useful for the development of an aromatase inhibitor-based protocol to control ovulation for herd synchronization and to enhance fertility by increasing circulating progesterone concentrations during the first 7 days post-AI or embryo transfer in cattle.
  Reproduction Fertility and Development 12/2011; 24(1):113. · 2.11 Impact Factor