The effects of dose and route of administration of prostaglandin in cattle
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Two studies were designed to determine effects of different doses of prostaglandin (PGF) by different routes of administration on luteolysis, behavioral and tissue responses, fertility, interval to estrus, luteinizing hormone (LH) peak and ovulation rate in cattle. In the first study, four experiments were done. In Experiment 1, 19 heifers with a functional CL (diameter /= 17 mm) were given cloprostenol as follows: 500 ug IM, 250 ug SC, or 100 ug SC. Compared to the groups given 500 ug IM or 250 ug SC, the group given 100 ug SC tended (P 0.05) to have a longer interval from treatment to estrus (means, 56.0, 57.6 and 88.8 h, respectively), and had a longer interval from treatment to ovulation (P 0.03; means 84.0, 92.0, and 120.0 h respectively. In Experiment 2, 28 heifers were given 5, 10 or 25 mg (Armour Standard) of pLH, followed in 7 d by cloprostenol (as described in Experiment 1 ), and a second dose of pLH (each heifer received the same dose as previously) 48 h later. There was no significant difference among treatment groups for luteolysis, ovulation rate (all heifers responded to the treatment) and interval from treatment to ovulation (mean, 101 h; P 0.9). In Experiment 3, 38 heifers with a functional CL (progesterone concentrations /= 1.0 ng/mL) received 500 or 125 ug cloprostenol by either IM or SC injection in a 2 x 2 factorial design. The interval from cloprostenol to estrus was shorter (P 0.02) in the group that received 500 ug IM (58.5 h) than in the other three groups (75.0, 78.0 and 82.3 h). However, there was no significant difference among groups in the interval from cloprostenol treatment to ovulation (mean, 110 h) or in the proportion of heifers that were detected in estrus (78.9percent; p 0.3) or ovulated (92.1 percent; p 0.6). In Experiment 4, 36 heifers received the same treatments as in Experiment 3 on Day 7 (ovulation = Day 0). The proportion of heifers detected in estrus and ovulating after 125 ug SC (33 and 44percent) or 125 ug IM (55 and 55percent) were lower (P 0.05) than those that received 500 ug SC (100 and 100percent); the proportion of heifers detected in estrus (77.0percent) and ovulating (88.0percent) after 500 ug IM were different (P 0.05) from the 125 ug SC group but not from the 125 ug IM group. In the second study, three experiments were conducted. In Experiment l, 21 nonpregnant, nonlactating Holstein cows at unknown stages of the estrous cycle were given 100 ug gonadotropin releasing hormone (GnRH) IM and 7 d later, 25 mg of dinoprost into the ischiorectal fossa (IRF). Sixteen of these cows were subsequently shown to have a functional CL and all had rapid and complete luteolysis. There were minimal adverse behavioral reactions to the IRF injections and no visual or palpable tissue reactions at the injection site. In Experiment 2, Holstein heifers (n = 74), at unknown stages of the estrous cycle, were given 25 mg dinoprost by IRF injection. Fifty-one heifers (68.9 percent) were subsequently shown to have a functional CL at dinoprost treatment; 24 to 30 h later, luteolysis had occurred in 45 heifers (serum progesterone 0.7 +- 0.4 ng/mL). Thirty-three heifers were detected in estrus and were either artificially inseminated or bred naturally; 21 of these (63.6percent) were diagnosed pregnant 45 to 60 d after breeding. In Experiment 3, crossbred beef heifers (n = 48) were randomly allocated to receive dinoprost 7 d after ovulation as follows: 25 mg IM (n = 9); 25 mg IRF (n = 10); 10 mg IRF (n = 10); 10 mg SC (n = 10); or 10 mg intravulvosubmucosal (IVSM; n = 9). The proportions of heifers detected in estrus and ovulating in the 10 mg IVSM group (0 and 11percent) were lower (P 0.05) than in the 25 mg IM (100 and 100 percent), 25 mg IRF (90 and 100 percent), or 10 mg IRF groups (80 and 80percent). Estrus rate in the 10 mg SC group was higher (P 0.05) than in the 10 mg IVSM (50 vs. 0percent) and ovulation rate tended (P 0.06) to be higher (50 vs 11 percent). Estrus and ovulation rates were lower (P 0.05) in the 10 mg SC group than in the heifers that received 25 mg IM or IRF. In summary, PGF by IRF or SC injections were as efficacious as an IM injection in inducing luteolysis in cattle. Reduced doses of PGF injected SC or IM were efficacious when administered to heifers at random stages of the estrous cycle or in an Ovsynch-type protocol. A reduced dose of PGF injected into the IRF was as efficacious as a full dose IM in heifers on Day 7 after ovulation. However, reduced doses of PGF injected SC. IM or IVSM were less efficacious. (The summary of this thesis was consulted at University of Saskatchewan. University Library Catalogue https://sundog.usask.ca/)
Autor/a
Colazo, Marcos German
Director/a
Mapletoft, Reuben J.;
Institución
University of Saskatchewan
Fecha
2002Tipo de documento
tesis de posgrado
Subtipo de documento
tesis de maestría
tesis de maestría
dc.language.iso
eng
Materias
Ganadería : : Ganado vacuno;
Ubicación en el estante: T 636.2=20 COLe
Utilizar el siguiente identificador (URI) para citar o enlazar este registro:
https://repo.unlpam.edu.ar/handle/unlpam/841Registros en colección
- Tesisp [327]