166 Superovulation with mainly constant doses of Pluset: reconsideration of the decreasing doses dogma

Typical superovulatory treatments use protocols based on FSH that contain varying LH levels depending on the commercial brand. These are administered in decreasing doses for 4 to 5 days. This research aimed to evaluate the response of donors to a superovulation protocol (SOV) where doses are mainly constant compared to decreasing doses protocol. Aberdeen Angus cows between 3 and 14 years old were randomly assigned to two treatment groups in a double-blind study. Group 1 (n = 7) was treated with the decreasing doses SOV protocol, and group 2 (n = 7) was treated with the mainly constant doses protocol. All animals received a controlled internal drug release (CIDR®) device of 1.9 g of progesterone (P4) (CIDR, Zoetis) for 7 days for group 1 and 8 days for group 2. The assessment started with cows receiving 5 mg of 17β-oestradiol (17-B Oestradiol Rio de Janeiro, Allignani Hnos S.R.L) and 100 mg of P4 (Progesterona Rio de Janeiro, Allignani Hnos S.R.L), followed by the superovulatory treatment 4 days after the application of the CIDR + 17β-oestradiol. Every 12 h, group 1 received, IM, 720 IU of pFSH (Pluset, Calier) with doses decreasing for 5 days (100 IU, 100 IU, 90 IU, 90 IU, 70 IU, 70 IU, 60 IU, 60 IU, 40 IU, 40yIU). Group 2 received, IM, 720 IU of pFSH in constant doses every 12 h for 5 days, following slightly higher doses during the first day (80 IU, 80 IU, 70 IU, 70 IU, 70 IU, 70 IU, 70 IU, 70 IU, 70 IU, 70 IU and 70 IU). In the morning and afternoon of the third day of treatment, all cows received 150 μg of D-Cloprostenol (Enzaprost DC, Biogenesis Bagó). Each donor was inseminated 12, 24, and 30 h after oestrus. Seven days later, collection of embryos was carried out nonsurgically. Embryos were classified according to stage of development and quality and washed and cryopreserved according to the IETS manual. The superovulatory response of both treatments was measured in terms of the number of corpora lutea (CL) and transferable embryos obtained. The differences of both superovulatory protocols were statistically analysed with a Student’s t-test for independent samples. There were no significant differences (P > 0.05) between the use of the decreasing and mainly constant dose protocols to superovulate donors measured, both in terms of number of CL (13.43 ± 3.9 vs. 10 ± 7.7) and transferable embryos obtained (11.71 ± 7.87 vs. 9.86 ± 7.56). This study demonstrated the effectiveness of a mainly constant dose protocol for superovulation with Pluset, having similar results to the decreasing protocol. In practice, constant-dosing protocols could decrease treatment errors, especially considering that the superovulation is normally carried out by farmers.

The authors acknowledge Barcia-Holzer, Cabaña Bototí Picú, Gualeguaychú, Entre Rios, Argentina.