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Fertility After Estrous Cycle Control Using Gonadotropin and Prostaglandin F₂ Treatment of Sows

Science and Education Administration U. S. Department of Agriculture, Beltsville, MD 20705

Abstract

Two experiments were conducted to determine farrowing rates in sows after estrus and ovulation were controlled by the use of gonadotropins and prostaglandin F₂ (PGF₂). Accessory corpora lutea (CL) were induced in 74 Yorkshire and Duroc sows by an injection of 1,500 IU of pregnant mare serum gonadotropin (PMSG) followed 72 hr later by 750 IU of human chorionic gonadotropin (HCG). Thirtyeight sows (Experiment 1) were injected on days 13 and 14 after HCG with 10 mg and 5 mg of PGF₂, respectively. Sows were artificially inseminated on the second day of estrus after PGF₂ treatment with 6 billion spermatozoa in the Beltsville L-l extender. Three groups of 12 sows each were used in Experiment 2. Group 2-1 sows were treated and inseminated as described for sows in Experiment 1. Groups 2-2 and 2-3 sows were injected on days 13 and 14 after HCG with 10 mg of PGF₂ and were injected at the time of a second PGF₂ injection with 1,000 IU of PMSG followed by 500 IU of HCG either 72 hr later (Group 2-2) or 96 hr later (Group 2-3). Groups 2-2 and 2-3 sows were artificially inseminated 30 to 32 hr after the 500 IU of HCG. Plasma progesterone was quantified in blood plasma to estimate whether corporalutea were present at the time of blood collection.

At the time of the first PGF₂ injection, plasma progesterone concentrations indicated that 89% of all sows had functional CL. The CL had regressed after PGF₂ treatment in 87% of the sows in Experiment 1 and Group 2-1 and in 100% of the sows in Groups 2-2 and 2-3. In Experiment 1 and Group 2-1, 70% of sows had a synchronized estrus 4 to 7 days after PGF₂ treatment; in Groups 2-2 and 2-3, 33% and 83%, respectively, had such an estrus. Percentage of inseminated sows that farrowed in Experiment 1 and Group 2-1 combined, in Group 2-2 and in Group 2-3 was 65.5, 25 and 75, respectively. These results showed that the treatment protocol used for sows in Group 2-3 effectively controlled ovulation and might facilitate the efficient use of artificial insemination in the pig.

¹ Reproduction Laboratory, Animal Physiology and Genetics Institute, Beltsville Agricultural Research Center, Beltsville, MD 20705. The author expresses appreciation to The Upjohn Co., for their generous gift of prostaglandin F2a (Prostin F2 Alpha), to Kathy Ogle and Dan Deaver for their technical assistance, and to L. T. Frobish, Chief of the Non-ruminant Nutrition Laboratory, Nutrition Institute, SEA, for use of the sows.

² Mention of a trade name, product of specific equipment does not constitute a guarantee or warranty by the U. S. Department of Agriculture and does not imply its approval to the exclusion of other products that may be suitable.