The Gonadotrophic Content of Pituitary Glands from Gilts at two Stages of Early Pregnancy and on two Levels of Energy Intake

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Abstract
Fifty-seven Duroc gilts were sacrificed at either 3 or 25 days after breeding and their pituitary glands obtained. The gilts had all been bred during their second estrous period. One-half of the gilts were given a full-feed ration while the others were limited-fed approximately 50% of the energy intake of the full group from a weight of 115 lb. to the time of sacrifice. The total gonadotrophic content of the anterior pituitary gland was assayed by the use of immature male chicks. The gonadotrophic content of pituitaries from gilts sacrificed at 3 days postbreeding was not sufficient to produce significant testes growth response above control chicks. The pituitary glands from gilts pregnant for 25 days possessed a significantly greater gonadotrophic content than those from gilts killed 3 days postbreeding. A commercial gonadotrophin containing 8,000 I.U. of chorionic gonadotrophin stimulated testes growth significantly more than pituitary material from gilts of 25-day pregnancy. The gonadotrophic content of 3 mg. of pituitary powder from gilts killed at 3 and 25-days postbreeding was estimated to be 236 and 1,948 I.U., respectively. The ration treatment to which gilts were subjected did not affect the gonadotrophin content of pituitary glands. The results also indicated that 3 mg. of anterior pituitary lobe powder per chick was sufficient for comparing gonadotrophin response due to stage differences. Copyright © . .