Some effects of adding p-LH in defined amounts to purified p-FSH to modify FSHLH ratios during the superovulatory treatment of anestrous ewes

Nonlactating Leccese ewes (n = 61) were used during seasonal anestrus to investigate the effects on ovarian response and embryo production of adding defined amounts of p-LH to purified p-FSH as well as decreasing the FSHLH ratio during treatment. The ewes were synchronized with FGA-impregnated intravaginal pessaries for 9 days and prostaglandin F2α (Cloprostenol) injected on the seventh day. They were divided into six treatment groups in a 3 × 2 factorial design: three amounts of purified p-LH (100, 50 or 25% equivalent to 525, 262 or 131 IU p-LH) × 2 regimen of p-FSH and p-LH administration (constant or decreasing FSHLH ratio). Each ewe received a total of 525 IU p-FSH at a decreasing dose, twice daily over a 3-day period. Group I (n = 11), Group II (n = 10) and Group III (n = 10) were treated with p-FSH supplemented with p-LH at 100%, 50% and 25%, respectively, of p-FSH dose and a constant FSHLH ratio throughout the treatment period. Group IV (n = 10), Group V (n = 10) and Group VI (n = 10) were treated with p-FSH supplemented with p-LH at 100%, 50% and 25%, respectively, of p-FSH dose but with a decreasing FSHLH ratio over the 3 days of the treatment: 1.7-0.86-0.43 for Group IV; 3.4-1.7-0.86 for Group V; 6-3-1.5 for Group VI. Embryos were flushed surgically on Day 6 after estrus. ulation rate did not differ among the groups (8–12.8). Superovulation with 100% p-LH and decreasing the FSHLH ratio (Group IV) resulted in: (i) the highest ova recovery (9.8 ± 1.7), and this was significant different (P < 0.05) from the 25% p-LH treated group (Group VI; 5.0 ± 1.7); (ii) the highest fertilization rate (90.6 ± 9.2%), with a significant (P < 0.01) difference compared with the constant ratio regimen (Group I; 62.6 ± 8.3%); (iii) the highest transferable embryo yield (6.4 ± 1.1), differing significantly (P < 0.01) from Group VI (2.2 ± 1.1) and Group I (2.7 ± 1.0). concluded that decreasing the amount of p-LH added to purified p-FSH did not improve the superovulatory response of ewes during the anestrous period. Transferable embryo production was significantly improved when ewes were treated with p-LH equivalent to 100% p-FSH, with the FSHLH ratio decreasing during treatment.