133 Effect of administration of mycobacterium cell wall fraction during the periovulatory period on the proportion of pregnancies obtained in virgin dairy heifers receiving in vitro-produced embryos
W. Brown A , M. Oliveria B , R. Reis Silva C , D. Demetrio B and J. Block AA Department of Animal Science, University of Wyoming, Laramie, WY, USA
B RuAnn Genetics, Riverdale, CA, USA
C Federal University of Goias, EVZ, Golania, CO, Brazil
Reproduction, Fertility and Development 35(2) 194-194 https://doi.org/10.1071/RDv35n2Ab133
Published: 5 December 2022
© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS
Pro-inflammatory cytokines play an important role in reproductive events that occur in the early post-oestrus period, including regulation of ovulation and recruitment of immune cells that assist in establishing uterine receptivity. The objective of the present study was to determine whether induction of a pro-inflammatory response during the periovulatory period could improve the proportion of pregnancies established per embryo transfer (P/ET) following the transfer of in vitro-produced (IVP) embryos. The study was conducted at a commercial dairy in central California from March to July 2022. Ovum pickup (OPU) was performed on a weekly basis using a cohort of virgin, Holstein heifers (n = 4), age 8–15 months. Each cohort was submitted to two successive OPUs at 14-day intervals. Prior to each OPU, donors were submitted to a follicle superstimulation regimen that included administration of gonadotrophin-releasing hormone (GnRH; Fertagyl®, Merck Animal Health, 129 µg, IM) 4 days before OPU, followed by a single injection of follicle stimulating hormone (FSH; Folltropin®, Vetoquinol, 80 mg, IM) 36 h later. Then, OPU was performed 46–48 h after FSH administration. The experiment included 8 separate cohorts of donor animals (n = 32). Following each OPU, recovered oocytes were submitted to in vitro embryo production (Ruann Genetics). At Day 7 after in vitro fertilisation, transferable embryos (stages 4 to 9 and grades 1 to 2, according to the classification criteria of the International Embryo Technology Society) were harvested from culture for ET. Virgin, Holstein heifers (n = 180), age 13–15 months, were used as recipients. Visual observation for the occurrence of spontaneous oestrus was performed on weekly basis. Following oestrus detection, recipients were randomly assigned to receive either sterile saline or mycobacterium cell wall fraction (MCWF; Amplimune®, NovaVive) with both treatments administered intramuscularly in a 5 mL dose. Treatments were administered ∼12–24 h after oestrus observation. At Day 7–8 after oestrus, a single IVP embryo was transferred fresh into all recipients with confirmed presence of a corpus luteum by rectal palpation. Blood was collected at Day 40 ± 3 of gestation for determination of pregnancy based on levels of pregnancy-associated glycoproteins (IDEXX PAG test). Data for P/ET was analysed using the PROC GLIMMIX procedure of SAS. Overall, there was no effect of administration of MCWF during the periovulatory period on P/ET (control: 55/83 = 66.3% vs MCWF: 52/88 = 59.1%). There was also no effect of embryo stage, embryo grade, day of transfer (i.e. 7 vs 8 days post-oestrus), number of prior services, or any two-way interactions on P/ET. Results of the present study indicate that induction of a pro-inflammatory response via administration of MCWF during the periovulatory period does not affect P/ET in virgin, dairy heifer recipients who receive IVP embryos.
