Observing cows in estrus and inseminating them at the optimal time are necessary steps for effective reproductive management of a dairy herd. However, increasing herd sizes can lead to reproductive inefficiency resulting in decreased profits on dairy herds. Synchronization of estrus, through pharmacological control, has been used to improve reproductive efficiency. Systematic breeding programs provide an organized approach for administering artificial insemination (AI) at first service. Moreover, reproductive management is based on a methodical approach for the entire herd rather than for the individual cow. Seven-hundred and thirty four Holstein cows from 16 commercial dairy herds were used to conduct this study evaluating three systematic breeding protocols; 14-d PGF2a, timed AI (TAI), and GnRH-PGF2α, in comparison with an untreated control group. Eight herds relied on visual observation as their primary method for detection of estrus, and 8 herds utilized the HeatWatch® (DDx, Inc., Denver, CO) electronic estrus detection system. The average days to first postpartum AI were longer for untreated control cows when compared to the other breeding protocols. First AI conception rates did not differ among control, 14-d PGF2a, or GnRH-PGF2a protocols, but were higher than the TAI protocol. However, first AI pregnancy rates were higher for untreated controls versus hormonally treated cows. Estrus characteristics associated with each protocol were also evaluated and no difference was detected across treatments. An economic analysis determining cost per pregnancy for each protocol when considering drug costs, and pregnancy rates, resulted in the highest cost per pregnancy for TAI followed by GnRH-PGF2a and 14-d PGF2a. These programs should be considered as tools for convenience and efficiency of estrus detection; however, reduced labor costs from less time spent on estrus detection may be offset by the cost of the drug protocols. Cost effectiveness must be calculated on an individual herd basis when deciding whether a systematic breeding program is the appropriate choice. / Master of Science

Prostaglandin F2a (PGF2a), oxytocin and gonadotropin releasing hormone (GnRH) have been used in bulls, rams, boars, stallions or rodents to increase sperm numbers in the ejaculate. Improving sperm quantity in the canine ejaculate would benefit all assisted reproductive techniques used in this species. The purpose of the present study was to evaluate the effects of PGF2a, oxytocin and GnRH on canine ejaculate characteristics. Eight, mature, medium size (25-30 kg), mixed breed dogs were randomly assigned to one of four treatment groups (N=2 dogs each); each group received one treatment per week for four weeks. Treatments were assigned based on a Latin Square design. A two-week training period was used to acclimate the dogs to manual semen collection. Treatments were 0.1 mg/kg PGF2a 15 minutes prior to collection, 2.5 units/dog oxytocin 10 minutes prior to collection, 50 mg/dog GnRH 60 minutes prior to collection, or 1.0 ml of saline 30 minutes prior to collection. An evaluator that was blinded to treatment analyzed ejaculate characteristics. Samples were evaluated for semen volume, concentration of spermatozoa per milliliter, motility, morphology, total sperm number and total morphologically normal motile sperm number (TNMS). In addition, a subjective ease of collection score was assigned following each collection (Scale 1-9, 1 being easiest to manually ejaculate). Semen concentration, motility and morphology were not different between treatments. Semen volume was greater for dogs treated with PGF2a or oxytocin compared to saline. Total sperm number and TNMS were greater when dogs were treated with PGF2a compared to oxytocin, GnRH and saline (p<0.05). The subjective ease of collection score was lower for dogs receiving PGF2a compared to GnRH or saline (p<0.05). In summary, administration of PGF2a or oxytocin prior to semen collection increased semen volume and PGF2a increased total sperm number in the ejaculate of the dog. It did not appear that treatment with GnRH had an effect on semen parameters evaluated in this study. / Master of Science

No description available.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The aim of this study was to verify if prostaglandin F2α (PGF2α) administered by intravulvosubmucous (IVSM) injection induces luteolysis by reaching the corpus luteum (CL) directly by a local absorption rote, preventing its metabolism in the lungs, or after absorption and distribution via the systemic circulation. In a first trial, the estrus rate of 1,937 beef cows was monitored for 5 days (25.6% of estrus). At day 5, the cows that did not show estrus received 1/5 of the standard dose of dinoprost IVSM (5 mg; n = 1440) and resulted in 68.2% of estrus in the next 5 days. However, in a second trial, the number of heifers detected in estrus after dinoprost injected via the IVSM (47.4%; n = 97) or intramuscular route (IM; 54.7%; n = 95) at day 5 was not different (P > 0.05). Based on serum progesterone concentrations, animals treated with 5 mg dinoprost at day 5 of the estrous cycle do not present functional luteolysis regardless of the administration route. At day 10 of the estrous cycle, luteolysis was variable in cows treated with 5 mg of dinoprost. Nevertheless, luteolysis occurred in all animals treated with 25 mg dinoprost independent of the estrous cycle day. After treatment, the PGF2α concentration did not differ in serum from uterine and jugular veins. This was further confirmed by measuring the concentration of 13,14-dihydro-15-keto- PGF (PGFM) after 5 mg dinoprost injection via the IM or IVSM route. Dinoprost IM- and IVSM-administered resulted in a similar PGFM serum pattern over time, suggesting the same absorption rate for both routes. Although anatomical evidences suggest that PGF2α injected IVSM could be taken direct to the ovaries, avoiding the systemic circulation, the results do not support this hypothesis. In summary, the route of PGF2α administration (IVSM or IM) resulted in similar serum concentrations of PGF2α, PGFM, and luteolysis. Taking all the results together, the PGF2α injection via IVSM reached the systemic circulation before reaching the ovary, and the effectiveness of low doses of PGF2α was dependent on luteal phase and not on the route of administration. / O presente trabalho teve por objetivo verificar se a prostaglandina F2α (PGF2α) administrada na submucosa vulvar (IVSM) induz a luteólise ao alcançar o corpo lúteo (CL) diretamente por uma via local, evitando sua metabolização nos pulmões, ou após a absorção e distribuição através da circulação sistêmica. Em um primeiro estudo, o estro de 1937 vacas de corte foi monitorado durante 5 dias (25,6% de estro). No dia 5, as vacas que não apresentaram estro receberam 5mg de dinoprost via IVSM (1/5 da dose padrão; n=1440), resultando em 68,2% de estro nos 5 dias seguintes. Todavia, em outro experimento utilizando a mesma dose, o número de novilhas detectadas em estro após o tratamento IVSM (47,4%, n=97) ou intramuscular (IM; 54,7%, n=95) no dia 5 não diferiu entre os grupos (P>0,05). Com base na concentração sérica de progesterona, os animais tratados com 5mg de dinoprost no dia 5 do ciclo estral não apresentaram luteólise funcional, independentemente da via de administração. Após o tratamento com 5mg dinoprost IM ou IVSM no dia 10 do ciclo, 3/5 e 2/5 animais apresentaram luteólise, respectivamente. Entretanto, a luteólise ocorreu em todos os animais tratados com 25mg de dinoprost, independente do dia do ciclo estral (dia 5 ou 10). A concentração de PGF2α não diferiu no soro das veias uterina e jugular. O mesmo foi observado quanto ao padrão de 13,14-dihidro-15-ceto prostaglandina F2α (metabólito de PGF2α; PGFM) sérico ao longo do tempo após a aplicação de 5 mg de dinoprost via IM ou IVSM. Em resumo, a via de administração de PGF2α (IVSM ou IM) resultou em concentrações séricas semelhante de PGF2α, PGFM e luteólise. Embora evidências anatômicas permitam sugerir que a PGF2α injetada via IVSM possa ser transportada diretamente aos ovários, a injeção de PGF2α via IVSM atinge a circulação sistêmica antes de chegar ao ovário, e a eficácia de baixas doses de PGF2α é dependente da fase luteal e não da via de administração.

No description available.