Reproductive and endocrine responses to short-term safflower seed supplementation in anestrous ewes synchronized with progestagen

Abstract

Abstract. This study investigated the effects of short-term supplementation with safflower seed, a linoleic-acid-rich oilseed, on reproductive performance and endocrine responses in Hungarian Merino ewes during the non-breeding season. Forty-four clinically healthy multiparous ewes were allocated to two equal groups: a control group and a safflower group. Ewes in the safflower group (n=22) received 75 g ewe−1 d−1 of whole safflower seed in addition to the standard ration during the 7 d sponge period, whereas control ewes (n=22) received no oilseed supplementation. All ewes were treated with an intravaginal sponge containing 60 mg medroxyprogesterone acetate for 7 d during April. At sponge removal, 500 IU equine chorionic gonadotropin (eCG) was administered intramuscularly. Ewes showing estrus were mated with proven fertile Merino rams (ewe : ram ratio of 5:1). Blood samples were collected on day 0, day 7, and immediately after mating on the day of estrus to determine serum estradiol (E2) and 13,14-dihydro-15-keto prostaglandin F2α (PGFM) concentrations. Pregnancy was diagnosed by transabdominal ultrasonography 50 d after mating, and reproductive parameters were calculated. Under the present experimental conditions, short-term safflower seed supplementation did not produce statistically detectable improvements in estrus rate, pregnancy rate, lambing rate, or litter size compared with the control group (p>0.05). Serum E2 concentrations increased, whereas PGFM concentrations decreased over time in both groups; however, no treatment effect or treatment × time interaction was detected. In conclusion, supplementation with 75 g ewe−1 d−1 of whole safflower seed during progestagen treatment was not associated with measurable improvements in reproductive outcomes or detectable changes in circulating E2 and PGFM concentrations.