335 EFFECT OF PATERNAL LINE OF DONOR ON SUPEROVULATORY RESPONSE AND EMBRYO QUALITY IN JAPANESE BLACK HEIFERS

Abstract

The objective of this study was to investigate the effect of paternal line of donor on superovulatory response and embryo quality in Japanese Black cattle. Japanese Black cattle have paternal lines that can be classified into the following, according to meat quality and the growth rate: ‘high marbling meat type’, ‘high growth rate type’ and ‘high marbling meat and high growth rate (intermediate type)’. We hypothesized that paternal line of donor may affect superovulatory response. One hundred and forty superstimulations were performed on 56 Japanese Black heifers, and data on superovulatory response and embryo collection were analyzed. Japanese Black donors used in this study were from the following 4 paternal lines: Kedaka (large-framed with high growth rate;; n = 9, 30 times), Fujiyoshi (intermediate type;; n = 22, 47 times), Shigekane (high marbling meat type;; n = 13, 40 times), and Tajiri (high marbling meat type and small-frame with slow growth rate;; n = 12, 23 times). Donors were synchronized using a CIDR-B (EAZI-BREED, InterAg, NZ) for 8 to 12 days, and 500 μg PGF analog (Resipron-C; Teikoku Zouki, Japan or Clopromate-C; Sumitomo, Japan) administered at CIDR removal. Superstimulation was initiated on Day 10 (Day 0 = day of estrus) of the synchronized cycle;; FSH (Antrin R10;; Denka, Japan) was administered twice daily for 4 days with decreasing doses for a total of 28 Armour units FSH. PGF analog was administered in the morning on the last day of FSH treatment. Donors were given 50 or 100 μg GnRH analog (Sporunen, Denka, or Conceral, Takeda Schering prau, Japan) at the time of estrus detection, and were inseminated 12 h after the onset of estrus. Embryos were recovered on Day 7 after AI. The numbers of CL and follicles were recorded with transrectal ultrasonography immediately after embryo recovery. Embryos were classified according to the IETS Manual. Data were analyzed by Kruskal-Wallis test combined with Scheffe’s multiple comparison test. There were no significant differences in CL numbers among paternal lines: Kedaka (9.5 ± 4.2), Fujiyoshi (8.5 ± 5.1), Shigekane (7.8 ± 5.0) and Tajiri (8.6 ± 4.1). Mean number of recovered ova/embryos per donor was significantly (P < 0.05) higher in the Kedaka line (8.4 ± 5.1) than in the Fujiyoshi (4.9 ± 4.1) and Shigekane (5.5 ± 7.0) lines. The percentages of viable embryos was greater (P < 0.05) in the Fujiyoshi (73.7%) and Shigekane lines (62.8%) than in the Tajiri line (50.9%), whereas the percentage of unfertilized oocytes was significantly (P < 0.05) higher in the Tajiri line (41.5%) than in the Fujiyoshi (17.5%) or Shigekane (26.1%) lines. The percentages of freezeable and transferable embryos were not significantly different among paternal lines. Data suggest that the paternal line had an effect on the superstimulatory response in Japanese Black heifers, and especially the number and percentage of viable embryos per donor.