89 EFFECT OF NONESTERIFIED FATTY ACIDS ON IN VIVO OR VITRO EMBRYO PRODUCTION IN KOREAN NATIVE CATTLE (HANWOO)

Abstract

Recent reports suggest that high concentrations of nonesterified fatty acids (NEFA) negatively affect oestrous cycle, fertility, in vitro oocyte maturation, embryo quality, and viability. This study was performed to determine the relationship between plasma concentration of NEFA and embryo quality in Hanwoo cattle. In experiment 1, embryo recovery rate from superovulated donor cows 7 days after AI was evaluated. Donors, at random stages of the oestrous cycle, received a CIDR (Day 0). On Day 7, 200 mg of FSH was administered followed by 40, 30, 20, and 10 mg of FSH in declining doses twice daily by intramuscular injection for 4 days. On the third day of FSH administration, 25 mg of prostaglandin F_2a was given and the CIDR was withdrawn. After FSH injections were complete, donors were artificially inseminated twice on Day 11 and 12 at 12-h intervals. At first AI, 250 μg of gonadotropin-releasing hormone (GnRH) was administered. During embryo collection, plasma samples were obtained from jugular veins to measure NEFA concentrations by chemistry analyzer. Next, the effect of NEFA on embryo development in vitro was examined (experiment 2). After in vitro maturation and fertilization of abattoir oocytes using standard procedures, zygotes were cultured in mSOFaa supplemented with 5% (vol/vol) oestrous cow serum (ECS) collected from 8 random cows representing 8 different NEFA concentrations (72.6, 126, 175.5, 244.6, 311, 393, 527.3, and 979 g dL^–1) and compared with mSOFaa without serum (no-serum control). Statistical analysis was performed by ANOVA (SAS 9.1, SAS Institute Inc., Cary, NC, USA) and Duncan's multiple range tests where appropriate. Recovery of total and transferable morulae and blastocysts was related to NEFA levels of donor cows. The donor group with the lowest plasma NEFA levels yielded the most embryos, of which most were high quality (n = 3, 173 ± 11 g dL^–1 NEFA; 14 ± 3 total recovered embryos of which 85 ± 7% were transferable). Higher NEFA plasma levels reduced both the absolute number of embryos recovered and the fraction of transferable embryos (n = 8, 301 ± 20 g dL^–1 NEFA with more than the 10 recovered of which 56 ± 5% were transferable; n = 6, 301.5 ± 37 g dL^–1 NEFA with 8 ± 2 total embryos recovered of which 19 ± 8% were transferable; n = 4, 288.5 ± 58 g dL^–1 NEFA with <7 embryos recovered of which 45 ± 4% were transferable). In experiment 2, cleavage and blastocyst rates were not significantly different (P > 0.05) between the groups. However, embryos exposed to the 2 lowest concentrations of NEFA showed a higher hatching rate compared with control and embryos exposed to the 3 highest NEFA levels (126 and 175.5 g dL^–1 NEFA: 75.33, 77.67% hatching respectively v. control, 979, 527.3, 393 g dL^–1 NEFA: 48.33, 32.78, 45.33, 44.52% hatching; P < 0.05). However, embryo developmental rate was highly variable. Our data suggest that high plasma NEFA concentrations can have negative effects on in vivo and in vitro embryo production, whereas low levels may be beneficial.

This research was supported by Bio-industry Technology Development Program (No.112130-3), Ministry for Food, Agriculture, Forestry and Fisheries, Republic of Korea.