Investigation of laparoscopic ovum-pickup in juvenile heifers followed by in vitro embryo production and embryo transfer in dairy cattle.

Abstract

The objectives of this pilot study were (1) to investigate the potential application of juvenile in vitro fertilization and embryo transfer (JIVET) in seasonal pasture based dairy systems and (2) to provide insights into donor and recipient management that might be useful in designing future studies. Oocytes were collected from the ovaries of elite Holstein Friesian donor calves (n = 49) by laparoscopic ovum pickup. Following in vitro maturation, oocytes were fertilized with frozen-thawed X-sorted semen from a panel of proven fertility Holstein Friesian sires (n = 8) and cultured for 7 d. A total of 87 embryos were transferred fresh to Holstein Friesian heifers or lactating dairy cows that had been synchronized using a progesterone-Ovsynch protocol. Pregnancy diagnosis was carried out using transrectal ultrasound at d 35 after synchronized estrus and was confirmed at d 63. Pregnancy loss was characterized as loss between d 35 and d 63. Gestation length (GL), birthweight (BiW), calving difficulty (CD) and vitality scores were recorded from the resulting calves (n = 21) and a contemporaneous cohort of calves derived from artificial insemination (AI; n = 44). Blood samples were collected from a subset (n = 35) of these calves for hematological analysis on d 0 and biochemical analysis on d 0 and d 14. There was evidence that the number of blastocysts produced (0.3 vs 2.1), and blastocyst yield (percentage of presumptive zygotes that formed blastocysts; 0.8% vs 15.1%) were both less for donors that had experienced a health event before LOPU than for those that had not. Fewer oocytes were recovered from donors that were in the bottom 25% category for plasma anti-Müllerian hormone (AMH) compared with those in the middle 50% category, and these in turn had lower oocyte recovery compared with donors in the top 25% category (3.9, 8.1 and 26.9, respectively). Fewer transferrable embryos were produced from donors that were in the bottom 25% category for plasma AMH compared with those in the middle 50% and the top 25% category (0.6, 1.1 and 4.4, respectively). Mean serum concentration of pregnancy specific protein-B (PSPB) on d 21 was lowest in recipients that were diagnosed not pregnant on d 35 (0.16 ng/mL) and was greatest in recipients that maintained the pregnancy to term (0.96 ng/mL). Gestation length and BiW were similar for calves derived from AI and JIVET. Calving difficulty and calf vigour scores were not affected by calf origin. In conclusion, donor calf health before LOPU and plasma AMH concentration were associated with subsequent embryo yield, and calves derived from JIVET had similar GL, BiW, CD and calf vigour scores to AI-derived calves.