ABSTRACT
Four trials were conducted to study synchronous estrous response in beef cows and in beef and dairy heifers to Luprostiol (13, thia-PG-F(2)alpha analog) in comparison with other prostaglandin products. In Trial 1, 60 virgin beef heifers were observed for estrus for 5 d and artificially inseminated. Heifers not observed in estrus within 5 d were randomly assigned to receive 15 mg Luprostiol or 25 mg Lutalyse. In Trial 2, 75 multiparous, lactating beef cows were randomly assigned to receive either 15 mg Luprostiol, 25 mg Lutalyse or 500 mcg Estrumate. All cows received a second injection of the respective treatment 11 d later. In Trial 3, 96 multiparous, lactating beef cows were randomly assigned to receive 15 mg Luprostiol or 25 mg Lutalyse. All cows received a second injection of the respective treatment 11 d later. In Trial 4, virgin dairy heifers were palpated per rectum. Seventy-seven heifers with a palpable corpus luteum (CL) were randomly assigned to receive 15 mg Luprostiol or 500 mcg Estrumate. In all trials animals were artificially inseminated 12 h following observed estrus. Estrous response during the 5-d synchronized period was 44% for Luprostiol and 42% for Lutalyse treated heifers in Trial 1. It was 52, 56 and 60%, respectively, for Luprostiol, Lutalyse and Estrumate treated cows in Trial 2; 23% for Luprostiol and 19% for Lutalyse treated cows in Trial 3; and 68% for Luprostiol and 70% for Estrumate treated heifers in Trial 4. Treatment with Luprostiol results in a similar synchronous estrous response as with the other prostaglandin products used in these studies.
ABSTRACT
Multiparous lactating beef cows were observed for estrus and randomly assigned to one of four Luprostiol (13, thia-PG-F(2)alpha analog) treatment groups receiving 3.8 (LI), 7.5 (LII), 15 (LIII) or 30 (LIV) mg Luprostiol, respectively, or to an untreated control group (C), or to a positive control group (E) receiving 500 mcg Estrumate. Cows received their respective treatments in a single dosage on Day 7, 8 or 9 of the estrous cycle (estrus = Day 0) and were artificially inseminated 12 h following the subsequent estrus. Blood samples were collected from all groups immediately prior to treatment and at 12-h intervals to 48 h post treatment and analyzed for progesterone (P(4)). Blood samples were collected at 3-h intervals from 24 to 72 h post treatment for animals in Group LIII and for 48 h (or observed estrus) starting on Day 19 of the estrous cycle for animals in Group C. These samples were analyzed for estradiol-17beta(E(2)), follicle stimulating hormone (FSH) and luteinizing hormone (LH). Treatment with Luprostiol at doses >/= 7.5 mg resulted in a synchronous estrous response during the first 5 d post treatment in 75 to 95% of cows treated. Luteal function, as evaluated by systemic P(4) concentration, paralleled results observed for estrous response. Treatment with a 15 or 30 mg dose of Luprostiol resulted in greater overall pregnancy rate at synchronized estrus. No biologically significant differences were found in blood levels of E(2), FSH or LH around the time of estrus between cows in Groups C and LIII. Results from these studies indicate treatment with Luprostiol at doses >/= 7.5 mg resulted in a synchronous estrus during the first 5 d after treatment. Pregnancy rates and endocrine changes were similar to those observed in control and Estrumate-treated cows.
