225 EFFECTS OF PEDIGREE, MEAT QUALITY, AND MEAT QUANTITY OF SLAUGHTERHOUSE DONOR COWS ON OOCYTE RECOVERY, EMBRYO DEVELOPMENT, AND PREGNANCY AFTER EMBRYO TRANSFER

Abstract

In conventional in vitro embryo production, oocytes are obtained from various ovaries, and donor characteristics, such as pedigree type, meat quality, or meat quantity, are not considered. The aim of this study was to examine the effects of pedigree type and meat quality and quantity of slaughterhouse donor cows on oocyte recovery, embryo development, and pregnancy rates. The ovaries of individual Korean native cows were obtained from a slaughterhouse. The ear tag numbers were obtained 24 h after slaughter, and the donor data were compared according to the pedigree type (no registration to third bloodline registration), meat quantity according to the percentage of carcass weight (more than 69%, 66 to 69%, and below 66%; Grades A, B, and C, respectively), and meat quality according to the marbling grade (marbling grade 8 to 9, 6 to 7, 4 to 5, 2 to 3, and 1; Grades 1⁺⁺, 1⁺, 1, 2, and 3, respectively). There were 390 donors in total, and each group had 30 donors. Recipients (Holstein heifers; n = 222) were synchronized with a progesterone device, and a single blastocyst was transferred nonsurgically on Day 7 from the onset of oestrus. Data on embryo development were compared by Duncan’s multiple range tests, and pregnancy rate was analysed by chi-square test. Values of P < 0.05 were considered to indicate a significant difference. No significant difference was detected in the average number of oocytes recovered (17.5 ± 2.9 to 22.9 ± 1.2%) or blastocyst development (16.4 ± 2.6 to 19.5 ± 3.4%) from cows of different pedigrees. A higher number of oocytes were recovered from Grade A (22.9 ± 1.0) than from Grade B (19.8 ± 0.7; P < 0.05) cows. However, the meat quantity grade had no significant effect on blastocyst development (14.3 ± 1.2 to 15.0 ± 0.8%). A greater number of oocytes were recovered from the Grade 1⁺⁺ (25.0 ± 1.6), 1⁺ (27.7 ± 2.4), and 2 (23.6 ± 1.5) groups than from the Grade 3 group (19.7 ± 1.0; P < 0.05). The developmental rate to the blastocyst stage was significantly higher in the Grades 2 and 3 groups (22.1 ± 2.2 and 19.4 ± 1.7) than in the Grade 1⁺⁺, 1⁺, and 1 groups (9.0 ± 1.2 to 13.8 ± 2.0). Pregnancy rate was not affected by pedigree type, meat quantity, or meat quality (41.7 to 58.6%). We concluded that 1) pedigree type had no effect on oocyte recovery and embryo development; 2) meat quantity affected oocyte recovery but did not affect embryo development; 3) high meat quality (Grades 1⁺⁺ and 1⁺) resulted in greater oocyte recovery but lower embryo development; and 4) pregnancy rate remained unaffected by pedigree type, meat quantity, and meat quality.