Reproductive performance of dairy cows with cystic ovaries following administration of Procystin.

Eighty-five postpartum Holstein cows were randomly assigned to receive 0, 50, 100, or 250 micrograms of the gonadotropin-releasing hormone product, Procystin when follicular cysts were diagnosed by palpation per rectum. Accurate reproductive records were maintained, and milk samples were collected at the time of diagnoses for assay for progesterone. An additional 101 cows were injected with only the 100 micrograms dose of Procystin when cysts were identified. Data showed that days from treatment to first observed estrus decreased with increasing doses of Procystin with no advantage of 250 micrograms over 100 micrograms. Days open and conception rates were similar among the treatment groups. Cows with less than 1 ng/ml progesterone in their milk at the time of treatment returned to estrus sooner than cows with progesterone concentrations greater than 1 ng/ml. In addition, gonadotropin-releasing hormone administered to those cows with low progesterone at the time of treatment led to significantly increased progesterone concentrations by 7 and 14 d posttreatment. We conclude that although Procystin administration hastened estrus of cows with ovarian cysts, breeding practices on the farms did not lead to an improvement in reproductive efficiency of the cows that possessed cysts.

Pregnancy rate among beef heifers from timed insemination following synchronization with a progestin treatment.

Five trials were conducted with 958 virgin beef heifers to evaluate the effects of various breeding management methods on pregnancy rate at synchronized estrus and during a 45-day artificial insemination (AI) season. Synchronization was achieved with the progestin treatment regimen Syncro-Mate-B (SMB). Pregnancy rate at first service and cumulative pregnancy rate were affected (P less than .01) by trial. Pregnancy rate at first service was 55% for all heifers on the SMB treatment regimen and 67% for nontreated control heifers (P less than .01). However, cumulative pregnancy rate during the 5-day synchronized period was higher (P less than .01) among treated heifers (54%) than among control heifers (21%). The pregnancy rate was 6% higher (P less than .06) after 27 days of breeding for treated heifers than for control heifers. Neither pregnancy rate at 21 days nor final pregnancy rate after a 45-day AI season was significantly affected by treatment. Pregnancy rate at first service among heifers undergoing the SMB treatment regimen and inseminated 12 hr after first detected in estrus was not significantly different from that among heifers inseminated once from 45 to 55 hr after implant removal or heifers inseminated twice at 48 and 60 hr after implant removal, regardless of occurrence of estrus.

The biological properties of aspartame. IV. Effects on reproduction and lactation.

Intragastric administration of approximately 300 mg/kg/day of aspartame (APM) to female rats for seven days and to female hamsters for five days after mating did not affect postcoital fertility as measured by the number of implantation sites and normal appearing fetuses. In additional studies, the effect of APM fed at 1 to 14% in the diet to lactating rats and their litters of suckling young was studied using a pair-feeding experimental design. Levels of APM up to 4% in the diet (about 7 g/kg/day) did not affect food consumption, body weights, serum prolactin, serum gonadotropins, the mammary gland histology of the dams or the growth and survival rates of their pups. However, higher levels of 7.5 and 14% APM (about 9 g/kg/day) caused reduced food consumption due to diet palatability and resulted in body weight loss in dams and retarded growth rates in the young.

Controlled drug release from polymeric delivery devices. III: In vitro-in vivo correlation for intravaginal release of ethynodiol diacetate from silicone devices in rabbits.

Forty female rabbits were implanted with silicone vaginal devices containing ethynodiol diacetate for up to 8 weeks. As predicted from in vitro studies, a Q - t1/2 (matrix-controlled) release profile was observed in vivo. The in vivo drug release profile was compared with in vitro data measured at three hydrodynamic conditions, and the diffusional resistance across the vaginal wall was estimated. Drug released from silicone devices yielded a prolonged plasma level when compared with data following intravaginal or intravenous administration of a solution dose. The rate constant for elimination was unchanged. The plasma concentration of the drug was related to the intravaginal drug release profile both theoretically and experimentally and was above the concentration required to inhibit fertilization.

11 beta-methyl-19-norsteroids: novel progestational hormones.

PIP: The synthesis and biological properties of 2 11beta-methyl-19-norsteroids (17alpha-ethynyl-17beta-hydroxy-11beta-methylestr-4en-3-one and 3beta, 17beta-diacetoxy-17alpha-ethynyl-11beta-methylestr-4-ene) are described. In experimental animals both compounds exhibited potent progestational activities, antiestrogenic activities, and estrogenic responses in the estrogen-deficient state. It is suggested that the latter compound may be similar to other progestational agents in failing to alter hepatic excretory function and may possess anovulatory properties without some of the side effects associated with steroid contraceptives presently employed.^ieng