Bovine somatotropin increases the pregnancy rate in fixed-time artificial insemination in beef cattle.

This study evaluated the effect of bovine somatotropin (bST) on pregnancy rate (PR) and size of the dominant follicle (DF) on the day of intravaginal progesterone (P4) removal in protocols for fixed-time artificial insemination (FTAI). Bos indicus (Nellore) females (n = 392) were distributed into three groups. The control group (CG; n = 92) received an intravaginal P4 device + estradiol benzoate on day (d)0; prostaglandin F2α on d7 (first application); removal of P4 + estradiol cypionate (EC) + PGF2α (second application) + ultrasound (US) of the DF on d9; the FTAI was performed on d11; and pregnancy diagnosis (PD) was performed on d45. The bST group (bSTG; n = 142) underwent the same protocol as the CG, except that the animals received 125 mg of bST on d7. The equine chorionic gonadotropin (eCG) group (eCGG; n = 158) underwent the same protocol as the CG, except that the animals received 300 IU of eCG on d9. The PRs of the bSTG, eCGG, and CG were 48%, 48%, and 35%, respectively (p < .05); the bSTG and eCGG showed greater PRs, with follicles 6-7.9 mm (p < .05) and 8-8.9 mm in diameter, respectively. The bSTG exhibited a greater dimension of the DF on d9 of the protocol (p < .05). The eCGG had higher PRs with a body condition score (BCS) of 2.5, and the bSTG had a BCS of 3.0 (p < .05). It was concluded that bST increased PR, bST showed better performance in smaller DF and larger follicular diameter on d9 of the protocol, eCG acted better on animals with lower BCSs, and bST can be used in FTAI.

Timed-artificial insemination protocols for Bos indicus beef heifers: Evaluation of protocol length and variations in prostaglandin F2α treatments.

The aim was to compare reproductive outcomes of Nelore heifers submitted to timed AI (TAI) protocols, with 7 or 9 d of permanence of the intravaginal progesterone (P4) device and different times of prostaglandin F2α (PGF) administration, for first (n = 935) and second (n = 530) services. On Day -24, heifers without corpus luteum (CL) underwent a protocol for induction of ovulation. On Day 0, heifers received a P4 device (0.5 g) and 1.5 mg estradiol (E2) benzoate. In order for the TAI to be carried out on the same day, these treatments were performed 2 d later on the heifers treated with the 7-d protocol. Additionally, heifers received 0.5 mg PGF at different times, resulting in four experimental groups: 9dP4-PGFd9 (n = 365); 9dP4-PGFd7 (n = 369); 9dP4-PGFd0&9 (n = 364); 7dP4-PGFd0&7 (n = 367). These nomenclatures indicate for how many d the P4 device was kept and the specific day on which PGF was given. At P4 removal, all heifers received 0.5 mg E2 cypionate and 200 IU eCG, and TAI was performed 2 d later. Effects were considered significant when P ≤ 0.05 (superscript letters a,b) whereas a tendency was assumed when 0.05 < P ≤ 0.10. Groups 9dP4-PGFd0&9 and 7dP4-PGFd0&7 had lower percentage of heifers with CL at P4 removal. The diameter (mm) of the dominant follicle (DF) was affected by treatment at P4 removal (9dP4-PGFd9: 11.3 ± 0.3b; 9dP4-PGFd7: 11.8 ± 0.2ab; 9dP4-PGFd0&9: 12.6 ± 0.2a; 7dP4-PGFd0&7: 10.8 ± 0.2c) and at TAI (9dP4-PGFd9: 12.7 ± 0.3ab; 9dP4-PGFd7: 13.2 ± 0.2a; 9dP4-PGFd0&9: 13.4 ± 0.2a; 7dP4-PGFd0&7: 12.4 ± 0.3b). Expression of estrus (%) was affected by treatment (9dP4-PGFd9: 89.6a; 9dP4-PGFd7: 93.5a; 9dP4-PGFd0&9: 88.2ab; 7dP4-PGFd0&7: 85.6b). There were no differences among treatments for P/AI on Day 40 (30-35 d post AI), final P/AI (between Day 70 and parturition) and pregnancy loss (between Day 40 and final P/AI). When the permanence of the P4 device was compared, regardless of PGF treatments, 9-d protocols resulted in greater DF diameter at P4 removal and at TAI, and greater expression of estrus (90.4 vs. 85.6%) than the 7-d protocol. Despite that, the 7-d protocol resulted in greater P/AI on Day 40 (55.3 vs. 49.1%). In addition, there was an interaction between protocol duration and body weight, in which heavier heifers (≥ 307 kg) had greater P/AI when treated with the 7-d protocol, in comparison to 9-d. In conclusion, longer TAI protocols (9 d of P4 device duration) resulted in greater DF diameter and expression of estrus. However, the shorter TAI protocol (7 d of P4 device duration) produced greater P/AI on Day 40, particularly in heavier heifers. Within 9-d protocols, the additional dose of PGF on Day 0 or the anticipation of the PGF to Day 7 did not influence fertility.

Prostaglandin F2α treatment does not hasten ovulation in weaned sows.

This study evaluated the efficiency of prostaglandin F2α (PGF) to hasten ovulation in weaned sows. In experiment I, weaned sows detected in estrus (0 h) received: no hormone (Control; n = 56); 0.5 mg PGF IM at 0 h and 2 h (PGF0; n = 56); or 0.5 mg PGF IM at 24 h and 26 h (PGF24; n = 55). In experiment II, weaned sows that did not express estrus signs until 72 h after weaning (0 h) were assigned to: no hormone (Control; n = 45); 10 µg buserelin acetate IM at 0 h (Buserelin; n = 43); 0.5 mg PGF IM at 34 h and 36 h (PGF; n = 44); or 10 µg buserelin acetate IM at 0 h plus 0.5 mg PGF IM at 34 h and 36 h (Buserelin + PGF; n = 45). In experiment I, no effect of PGF on the interval treatment onset to ovulation was observed (P > 0.05), and no treatment effect was observed on the relative or cumulative proportion of females that ovulated post-treatment onset (P > 0.05). In experiment II, treatment onset to ovulation interval was shorter for Buserelin group than for PGF group (P < 0.05), and a higher cumulative percentage of Buserelin treated sows ovulated up to 48 h compared to PGF and Control groups (P < 0.01), with no differences from Buserelin + PGF. Treatments did not affect total number of piglets born in both experiments (P > 0.05). In conclusion, PGF did not hasten ovulation timing or affect litter size in weaned sows.

Early maturation of corpus luteum in rabbits - effect of sildenafil citrate on luteolytic capacity in the early luteal period

Background: Prostaglandin F2 alpha (PGF2 α) binds to the specific receptor (PTGFR) on the corpus luteum (CL) in mammals, inducing regression of the CL structure (luteolysis) and initiating a new cycle. While PGF2 α is effective only on mature CL, the immature CL structure (early luteal phase) resists PGF2 α. In this study, sildenafil citrate, which is used to increase blood flow in the genital organs for treating specific pregnancy issues in women, was administered during the early luteal phase in a rabbit model to test the hypothesis of enhancing blood flow to the CL, thereby promoting earlier maturation and enabling a response to PGF2 α. Materials, Methods & Results: The study was conducted in 2 sub-studies: clinical and molecular. A large number of rabbits were initially included in the sub-studies to ensure a sufficient number of pseudo-pregnant rabbits. Ovulation in rabbits was induced with buserelin acetate and was considered as day 0 of the study. The sub-studies were continued with rabbits whose pseudo-pregnancies were confirmed according to progesterone (P4 ) results. As a result, the studies were continued with a total of 41 pseudo-pregnant New Zealand female rabbits, 21 of which were included in the clinical sub-study and 20 in the molecular sub-study. In both sub-studies, on day 3 of the luteal period, rabbits in the treatment group received 5 mg/kg sildenafil citrate and all rabbits received a single dose of exogenous PGF2 α on day 4 to induce luteolysis. In the clinical sub-study, echotexture and intraovarian blood flow changes in the ovaries were determined by ultrasonography (USG) examination. In the molecular sub-study, the expression changes of Hypoxia Inducible Factor 1 Alpha (HIF1A) and Vascular Endothelial Growth Factor (VEGF) related to angiogenesis, Steroidogenic Acute Regulatory Protein (StAR) related to P4 metabolism, Prostaglandin-Endoperoxide Synthase 2 (PTGS2) related to prostaglandin (PG) mechanism and 15-Hydroxyprostaglandin Dehydrogenase (HPGD) genes at mRNA level were determined using Real Time Polymerase Chain Reaction (RT-PCR) in CL tissues obtained with ovariohysterectomy (OVH) at 1 and 12 h after PGF2 α injection. In addition, blood samples were collected for determine P4 levels from all rabbits. In the clinical sub-study; there was no difference between the groups in mean gray values (MGV), whereas there was a significant decrease in both pulsatile index (PI) and resistance index (RI) values at 40 min after PGF2 α injection (P < 0.05). In the molecular sub-study, it was determined that sildenafil citrate had no significant effect (P > 0.05) on the expression levels 1 and 12 h after PGF2 α injection. According to the results of the molecular sub-study, no significant effect of sildenafil citrate on the mRNA expression levels in the investigated genes was detected (P > 0.05). However, within each group, differences were found according to OVH time after PGF2 α injection. It was observed that PTGS2 and HPGD mRNA expressions decreased at the 12th h compared to the 1st h, while HIF1A expression increased (P < 0.05). Discussion: According to the results obtained from clinical and molecular sub-studies, it was determined that a single dose of sildenafil citrate (5 mg/kg) applied on the 3rd day of the luteal period did not contribute to the maturation process of the CL, did not increase blood flow, and was insufficient to break the resistance of the CL against PGF2 α applied on the 4th day of the luteal period. However, a significant decrease in the PI value at the 40th min after PGF2 α injection suggests that sildenafil citrate has a supportive effect, and that this decrease is also seen in the RI value, suggesting that its effect is insufficient against the vasoconstrictive effect of PGF2 α.

Abordagem terapêutica hormonal para cistos foliculares ovarianos em vacas leiteiras - relato de casos / Hormonal therapeutic approach for ovarian follicular cysts in dairy cattle - case reports / Enfoque terapéutico hormonal para quistes foliculares ováricos en vacas lecheras - informe de casos

Vacas de alta produção de leite estão mais sujeitas a desequilíbrios metabólicos pós-parto, influenciando na performance reprodutiva subsequente. Alterações relacionadas a funcionalidade do ovário podem desencadear desequilíbrios hormonais e desordens reprodutivas, como a formação de cistos ovarianos, os quais podem interferir no processo de ovulação e impactar substancialmente na eficiência reprodutiva. Neste estudo de caso em específico, sete vacas leiteiras foram diagnosticadas com a presença de cistos foliculares ovarianos. Foram submetidas a terapia hormonal envolvendo o uso de análogos de Hormônio Liberador de Gonadotrofinas (GnRH) e prostaglandina-F2a (PGF-2a), a qual apresentou resultados satisfatórios. A abordagem terapêutica hormonal tem sido amplamente utilizada devido à sua efetividade na resolução dos cistos ováricos e melhoria da função reprodutiva. É fundamental que o médico veterinário tenha conhecimento clínico sobre a abordagem adequada de cistos ovarianos, a fim de proporcionar saúde e bem-estar aos animais, garantindo bons índices em produção de leite e desempenho reprodutivo.

High milk production cows are more likely to postpartum metabolic imbalances, which may influence subsequent reproductive performance. Changes in ovarian functionality can trigger hormonal alterations and reproductive disorders, such as the formation of ovarian cysts, which can interfere with the ovulation process and substantially impact reproductive efficiency. In this specific case study, seven dairy cows were diagnosed with the presence of ovarian follicular cysts. They were submitted to hormonal therapy involving the use of Gonadotropin-Releasing Hormone (GnRH) and prostaglandin F2a (PGF-2a) analogs, which presented satisfactory results. Hormonal therapeutic approaches have been widely employed due to their effectiveness in resolving ovarian cysts and improving reproductive function. It is essential for the veterinarian to have clinical knowledge about the appropriate management of ovarian cysts in order to provide the health and welfare of the animals, ensuring suitable rates in milk production and reproductive performance.

Las vacas de alta producción de leche tienen mayor probabilidad de desequilibrios metabólicos posparto, lo cual puede influir en el rendimiento reproductivo posterior. Los cambios en la funcionalidad ovárica pueden desencadenar alteraciones hormonales y trastornos reproductivos, como la formación de quistes ováricos, que pueden interferir en el proceso de ovulación y afectar sustancialmente la eficiencia reproductiva. En este estudio de caso específico, se diagnosticó la presencia de quistes foliculares ováricos en siete vacas lecheras. Se sometieron a terapia hormonal que incluyó el uso de análogos de Hormona Liberadora de Gonadotropinas (GnRH) y prostaglandina F2α (PGF-2a), lo cual arrojó resultados satisfactorios. Los enfoques terapéuticos hormonales se han utilizado ampliamente debido a su efectividad en la resolución de quistes ováricos y la mejora de la función reproductiva. Es fundamental que el médico veterinario tenga conocimiento clínico sobre el manejo adecuado de los quistes ováricos para garantizar la salud y el bienestar de los animales, asegurando adecuadas tasas de producción de leche y rendimiento reproductivo.

Prostaglandin F2α treatment concurrent with artificial insemination does not affect bovine embryo production / Administração de prostaglandina F2 alfa no momento da inseminação artificial não afeta a produção de embriões bovinos

Treatment with prostaglandin F2α (PGF) induces ovulation and increases conception rates in cows, while improving embryo production in buffalos. However, its effect on superovulated cows is unknown. This study verified whether single PGF administration concurrent with artificial insemination (AI) improves fertilization and embryo production rates in superovulated cows. In each replicate, embryo donor cows were equally allocated to two groups: the untreated control and PGF groups. The latter of which received 482 µg of cloprostenol concurrent with the first AI. Each cow (n = 35) was subjected to two superovulations (SOV) in a crossover design (total = 70 embryo collections). In the control and PGF groups, respectively, the observed responses were [median (95% CI)]: 12 (10-18) and 15 (12-18) total structures, 9 (7-11) and 7 (6-10) viable embryos, 1 (0-1) and 1 (1-3) degenerated embryos, and 1 (0-3) and 2 (0-5) oocytes (P > 0.05). In conclusion, single PGF treatment concurrent with the first AI did not affect embryo production in superovulated cows.

A prostaglandina F2α (PGF) pode induzir a ovulação e melhorar tanto a concepção em vacas, como a produção de embriões em búfalas, mas o efeito em vacas superovuladas é desconhecido. Esse estudo teve como objetivo verificar se a administração de uma dose de PGF na inseminação artificial (IA) após a superovulação (SOV) melhora as taxas de fecundação e produção embrionária em vacas. Em cada replicação, vacas doadoras de embriões foram equilibradamente alocadas em dois grupos: controle, não tratado, ou PGF, que recebeu 482 µg de cloprostenol no momento da primeira IA. Cada doadora (n = 35) foi submetida a duas SOV em um delineamento crossover (total = 70 coletas de embriões). Nos grupos controle e PGF, respectivamente, foram observados [medianas (IC 95%)]: 12 (10-18) e 15 (12-18) estruturas totais; 9 (7-11) e 7 (6-10) embriões viáveis; 1 (0-1) e 1 (1-3) embriões degenerados; e 1 (0-3) e 2 (0-5) ovócitos (P > 0,05). Conclui-se que uma única administração de PGF no momento da primeira IA não afeta a produção embrionária de vacas superovuladas.

Superovulatory response and embryo quality in Boer does following dietary supplementation with different sources of omega-3 and omega-6 fatty acids during the breeding season.

The purpose of this study was to determine effects of various sources of omega-3 and omega-6 fatty acids on ovarian response and embryo quality in Boer does when there was a superovulation treatment regimen imposed. Pluriparous does were randomly assigned to be treated with 300 g of one of four experimental supplements containing linseed oil (LO), soybean oil (SO), palm oil (PO), or a control supplement without fatty acids (CO), for 15 days. Does were fitted with a controlled internal drug release (CIDR) device containing 0.3 g progesterone for 7 days. At 48 h before CIDR withdrawal, does were treated with 80 mg follicle-stimulating hormone (FSH) administered at 12 h intervals. Embryos were collected 7 days after the last natural mating. Estrous response and interval between CIDR withdrawals to estrous onset were similar between treatments (P > 0.05). Number of ovulations was similar for does in the different groups (10.0, 9.2, 7.0, and 7.0, in LO, SO, PO, and CO, respectively; P > 0.05). There was premature luteal regression in does of the SO, PO, and CO groups, except in LO group. The LO-treated does had a larger (P < 0.05) mean number of ova/embryos recovered than does of SO, PO, and CO groups (7.2, 2.0, 0.2, 0.2, respectively) and transferable embryos (5.1, 1.4, 0.2, 0.2, respectively). These results indicate that including LO in supplements may be a feasible strategy for preventing premature luteal regression and improving embryo quality in goats treated to induce follicular super-stimulation for induction of superovulation.

Progesterone dose during synchronization treatment alters luteinizing hormone receptor and steroidogenic enzyme mRNA abundances in granulosa cells of Nellore heifers.

The objective was to investigate effects of progesterone (P4) dose on abundance of luteinizing hormone receptor (LHCGR), aromatase (CYP19A1), 3ß-hydroxysteroid dehydrogenase (HSD3B1), and other steroidogenic mRNA transcripts in granulosa cells from dominant follicles. Nellore heifers were assigned to one of six groups: new, first-use controlled internal drug release device (CIDR1) inserted for 5 days (Large-P4-dose-D5; n = 7) or 6 days (Large-P4-dose-D6; n = 8), prostaglandin (PG)F2α administered on D0 and 1 previously-used CIDR (CIDR3) inserted for 5 days (Small- P4-dose-D5; n = 8) or 6 days (Small-P4-dose-D6; n = 8), CIDR1 inserted on D0 and removed plus PGF2α on D5 (Large-P4-dose-proestrus (PE); n = 7), and CIDR3 and PGF2α on D0 and 1, CIDR3 removed plus PGF2α on D5 (Small-P4-dose-PE; n = 7). Duration of P4 treatment (D5 compared to D6) affected abundances of CYP19A1 mRNA transcripts, with there being greater abundances on D6 than D5 (P ≤ 0.05). Heifers treated with the large dose of P4 had a smaller dominant follicle, less serum and intra-follicular estradiol (E2) concentrations (P ≤ 0.05) and lesser LHCGR, CYP19A1, and HSD3B1 transcript abundances (P ≤ 0.05). Heifers treated to induce PE had a larger follicle diameter (P = 0.09), greater intra-follicular E2 concentrations and larger abundances of CYP19A1 mRNA transcript (P ≤ 0.05) than heifers of the D6 group. Overall, treatment with larger doses of P4 resulted in lesser abundances of LHCGR, HSD3B1, and CYP19A1 mRNA transcripts; thus, potentially leading to development of smaller dominant follicles and lesser E2 concentrations.

Timed artificial insemination in crossbred mares: Reproductive efficiency and costs.

Timed artificial insemination (TAI) has boosted the use of conventional artificial insemination (CAI) by employing hormonal protocols to synchronize oestrus and ovulation. This study aimed to evaluate the efficiency of a hormonal protocol for TAI in mares, based on a combination of progesterone releasing intravaginal device (PRID), prostaglandin (PGF2α ) and human chorionic gonadotropin (hCG); and compare financial costs between CAI and TAI. Twenty-one mares were divided into two groups: CAI group (CAIG; n = 6 mares; 17 oestrous cycles) and TAI group (TAIG; n = 15 mares; 15 oestrous cycles). The CAIG was subjected to CAI, involving follicular dynamics and uterine oedema monitoring with ultrasound examinations (US), and administration of hCG (1,600 IU) when the dominant follicle (DF) diameter's ≥35 mm + uterine oedema + cervix opening. The AI was performed with fresh semen (500 × 106 cells), and embryo was recovered on day 8 (D8) after ovulation. In TAI, mares received 1.9 g PRID on D0. On D10, PRID was removed and 6.71 mg dinoprost tromethamine was administered. Ovulation was induced on D14 (1,600 IU of hCG) regardless of the DF diameter's, and AI was performed with fresh semen (500 × 106 cells). On D30 after AI, pregnancy was confirmed by US. The pregnancy rate was 80.0% in TAIG and 82.3% in CAIG (p > .05). The TAI protocol resulted in 65% reduction in professional transport costs, and 40% reduction in material costs. The TAI was as efficient as CAI, provided reduction in costs and handlings, and is recommended in mares.

Prostaglandin F2α as ovulatory stimulus in dairy cows and buffaloes raised in the Amazon biome / Prostaglandina F2α como estímulo ovulatório em vacas e búfalas leiteiras criadas no bioma Amazônia

This study evaluated the effect of a prostaglandin F2? (PGF) analogue as an ovulatory stimulus in dairy cows and buffaloes raised in the Amazon biome. To this end, three experiments were performed in the state of Rondônia, located in the Amazon biome. In Experiment 1, 22 lactating dairy buffaloes received 2 mg of intramuscular (I.M.) estradiol benzoate (EB) on day 0 and an intravaginal progesterone-releasing device (CIDR) from day 0 to day 9 of the protocol. On days 8 and 9, all cows were given 500 ?g of I.M. d-cloprostenol (PGF analogue). On day 10, buffaloes were divided into two groups to receive 500 ?g of PGF (PGF group, n = 8) or no treatment (CTL group, n = 14), respectively. In Experiment 2, 16 lactating crossbred dairy cows (Holstein x Gir) received 2 mg of EB on day 0 and a CIDR insert from day 0 to day 8. On days 7 and 8, all cows were given 500 ?g of d-cloprostenol. On day 9, cows were divided into two groups to receive 500 ?g of d-cloprostenol (PGF group, n = 8) or no treatment (CTL group, n = 8), respectively. In Experiment 3, 16 lactating crossbred dairy cows (Holstein x Gir) were handled and treated similarly as in Experiment 2, although cows did not receive d-cloprostenol on day 8. Single-point outcome variables were analyzed using one-way analysis of variance (ANOVA), while proportions with dichotomous outcomes were analyzed with the chi-square test.

O objetivo deste estudo foi avaliar o efeito de um análogo de prostaglandina F2α (PGF) como indutor ovulatório em vacas leiteiras e búfalas. Para este fim, três experimentos foram realizados no estado de Rondônia, localizado no bioma Amazônia. No Experimento 1, 22 búfalas leiteiras em lactação receberam 2 mg de benzoato de estradiol (EB) im, no Dia 0 e um dispositivo intravaginal de liberação de progesterona (CIDR) do Dia 0 ao Dia 9 do protocolo. Nos Dias 8 e 9, todas as vacas receberam 150μg de d-Cloprostenol (análogo PGF), im. No Dia 10, as búfalas foram divididas em dois grupos para receber 150μg de PGF (Grupo PGF, n = 8) ou nenhum tratamento (Grupo CTL, n = 14). No experimento 2, 16 vacas leiteiras mestiças (Holandês x Gir) receberam 2 mg de EB no Dia 0 e um dispositivo intravaginal (CIDR) do Dia 0 ao Dia 8. Nos Dias 7 e 8 todas as vacas receberam 150μg de d-Cloprostenol. No Dia 9, as vacas foram divididas em dois grupos para receber 150μg de d-Cloprostenol (Grupo PGF, n = 8) ou nenhum tratamento (Grupo CTL, n = 8). No Experimento 3, 16 vacas leiteiras mestiças (Holandês x Gir) foram tratadas da mesma forma que no Experimento 2, porém, as vacas não receberam d-Cloprostenol no Dia 8. Variáveis quantitativas foram analisados por análise de variância - one-way ANOVA e variáveis dicotômicas foram analisados pelo teste do qui-quadrado. No Experimento 1, não houve diferença (P = 0,30) na taxa de ovulação entre os grupos, em média 68% das búfalas ovularam após o tratamento. Além disso, não houve diferença entre os grupos no intervalo de ovulação (P = 0,61) e no diâmetro do folículo pré-ovulatório (P = 0,47). No Experimento 2, apenas uma vaca do Grupo PG não ovulou. Não houve diferenças no intervalo de ovulação entre os grupos CTL e PG (P = 0,69). Em média, a ovulação ocorreu 82 horas após a remoção do CIDR. No Experimento 3, vacas tratadas com PGF ovularam antes do Grupo CTL (62,5 ± 5,8 vs 94,5 ± 13,5 h; P = 0,05). Coletivamente, esses resultados sugeriram que a PGF antecipa a ovulação em vacas leiteiras em lactação, porém seu efeito não foi observado em búfalas.

Prostaglandin F2α as ovulatory stimulus in dairy cows and buffaloes raised in the Amazon biome / Prostaglandina F2α como estímulo ovulatório em vacas e búfalas leiteiras criadas no bioma Amazônia

This study evaluated the effect of a prostaglandin F2? (PGF) analogue as an ovulatory stimulus in dairy cows and buffaloes raised in the Amazon biome. To this end, three experiments were performed in the state of Rondônia, located in the Amazon biome. In Experiment 1, 22 lactating dairy buffaloes received 2 mg of intramuscular (I.M.) estradiol benzoate (EB) on day 0 and an intravaginal progesterone-releasing device (CIDR) from day 0 to day 9 of the protocol. On days 8 and 9, all cows were given 500 ?g of I.M. d-cloprostenol (PGF analogue). On day 10, buffaloes were divided into two groups to receive 500 ?g of PGF (PGF group, n = 8) or no treatment (CTL group, n = 14), respectively. In Experiment 2, 16 lactating crossbred dairy cows (Holstein x Gir) received 2 mg of EB on day 0 and a CIDR insert from day 0 to day 8. On days 7 and 8, all cows were given 500 ?g of d-cloprostenol. On day 9, cows were divided into two groups to receive 500 ?g of d-cloprostenol (PGF group, n = 8) or no treatment (CTL group, n = 8), respectively. In Experiment 3, 16 lactating crossbred dairy cows (Holstein x Gir) were handled and treated similarly as in Experiment 2, although cows did not receive d-cloprostenol on day 8. Single-point outcome variables were analyzed using one-way analysis of variance (ANOVA), while proportions with dichotomous outcomes were analyzed with the chi-square test.(AU)

O objetivo deste estudo foi avaliar o efeito de um análogo de prostaglandina F2α (PGF) como indutor ovulatório em vacas leiteiras e búfalas. Para este fim, três experimentos foram realizados no estado de Rondônia, localizado no bioma Amazônia. No Experimento 1, 22 búfalas leiteiras em lactação receberam 2 mg de benzoato de estradiol (EB) im, no Dia 0 e um dispositivo intravaginal de liberação de progesterona (CIDR) do Dia 0 ao Dia 9 do protocolo. Nos Dias 8 e 9, todas as vacas receberam 150μg de d-Cloprostenol (análogo PGF), im. No Dia 10, as búfalas foram divididas em dois grupos para receber 150μg de PGF (Grupo PGF, n = 8) ou nenhum tratamento (Grupo CTL, n = 14). No experimento 2, 16 vacas leiteiras mestiças (Holandês x Gir) receberam 2 mg de EB no Dia 0 e um dispositivo intravaginal (CIDR) do Dia 0 ao Dia 8. Nos Dias 7 e 8 todas as vacas receberam 150μg de d-Cloprostenol. No Dia 9, as vacas foram divididas em dois grupos para receber 150μg de d-Cloprostenol (Grupo PGF, n = 8) ou nenhum tratamento (Grupo CTL, n = 8). No Experimento 3, 16 vacas leiteiras mestiças (Holandês x Gir) foram tratadas da mesma forma que no Experimento 2, porém, as vacas não receberam d-Cloprostenol no Dia 8. Variáveis quantitativas foram analisados por análise de variância - one-way ANOVA e variáveis dicotômicas foram analisados pelo teste do qui-quadrado. No Experimento 1, não houve diferença (P = 0,30) na taxa de ovulação entre os grupos, em média 68% das búfalas ovularam após o tratamento. Além disso, não houve diferença entre os grupos no intervalo de ovulação (P = 0,61) e no diâmetro do folículo pré-ovulatório (P = 0,47). No Experimento 2, apenas uma vaca do Grupo PG não ovulou. Não houve diferenças no intervalo de ovulação entre os grupos CTL e PG (P = 0,69). Em média, a ovulação ocorreu 82 horas após a remoção do CIDR. No Experimento 3, vacas tratadas com PGF ovularam antes do Grupo CTL (62,5 ± 5,8 vs 94,5 ± 13,5 h; P = 0,05). Coletivamente, esses resultados sugeriram que a PGF antecipa a ovulação em vacas leiteiras em lactação, porém seu efeito não foi observado em búfalas.(AU)

Effect of additional PGF2α dose on pregnancy rate in Nellore females subjected to FTAI / Efeito de dose adicional de PGF2α sobre a taxa de gestação de fêmeas bovinas Nelore submetidas a IATF

This study examined the effect of administering an additional dose of prostaglandin F2 alpha (PGF2α), in a fixed-time artificial insemination protocol (FTAI), on the fertility of female Nellore cattle. Two experiments were carried out: the first (Experiment I) took place in the state of Tocantins and the second (Experiment II) in the state of Pará, Brazil. In Experiment I (E1), 80 cows were used in three treatments (T1, T2 and T3) in which all received the same FTAI protocol. In T1 (n = 29), the cows received 12.5 mg of Dinoprost on day 9; in T2 (n = 28), they received the additional dose on day 10; and in T3 (n = 23; control group), the animals did not receive the additional PGF2α dose. Experiment II consisted of 147 bovine females distributed into two treatment groups, namely, T1 - 72 animals receiving the same protocol as T1 of E1; and T2 - 75 animals receiving the same protocol as T3 of E1. Statistical analysis was performed using SAS software, applying the PROC NPARWAY procedure for E1, and means were compared by the Wilcoxon test at the 5% significance level. In Experiment II, the data were subjected to analysis of variance by PROC GLIMMIX and means were compared by the T test at the 5% significance level. The following pregnancy rates were obtained in Experiment I: T1 - 62.06% (18/29); T2 - 57.14% (16/28); and T3 - 52.17% (12/23), with no significant difference observed between treatments. In Experiment II, pregnancy rate in T1 was 66.67% (48/72), whereas in T2 it was 41.33% (31/75), with a significant difference detected (P < 0.05). An additional dose of PGF2α provides an increase in pregnancy rate in Nellore females.(AU)

Objetivou-se avaliar o efeito da administração de uma dose adicional de prostaglandina F2 alfa (PGF2α) em protocolo de inseminação artificial em tempo fixo (IATF) sobre a fertilidade de fêmeas bovinas da raça Nelore. Foram realizados dois experimentos, sendo um (E1) no estado do Tocantins e o segundo (E2) no estado do Pará. No experimento 1 (E1) foram utilizadas 80 fêmeas bovinas distribuídas em três tratamentos (T1, T2 e T3), todos animais receberam o mesmo protocolo de IATF, diferindo no T1 (n=29), que recebeu 12,5 mg de Dinoprost no dia 9, T2 (n=28) recebeu a dose adicional no dia 10 e o T3 (n=23) - Grupo controle, que não recebeu a dose adicional de PGF2α. O experimento 2 (E2) constituído por 147 fêmeas bovinas distribuídas em dois tratamentos. T1: com 72 animais, recebendo mesmo protocolo do T1 do E1. T2: constituído por 75 animais, com protocolo idêntico ao T3 do E1. A análise estatistica foi realizada no programa SAS, sendo no E1 utilizando-se o PROC NPARWAY e as médias comparadas pelo teste de Wilcoxon com nível de significância de 5%. No E2 os dados foram submetidos à análise de variância pelo PROC GLIMMIX e as médias comparadas pelo teste T com nível de significância de 5%. No experimento 1 a taxa de prenhez no T1 foi de 62,06% (18/29), T2 de 57,14% (16/28) e T3 de 52,17% (12/23), não sendo observada diferença significativa entre os tratamentos. No experimento 2 a taxa de prenhez do T1 foi de 66,67% (48/72), enquanto T2 foi de 41,33% (31/75), verificando-se diferença significativa (P < 0,05). A dose adicional de PGF2α promoveu incremento na taxa de prenhez de fêmeas Nelore.(AU)

Administration of a single dose of a PGF2α analogue (dinoprost) before sexual tests did not improve ram's sexual behaviour.

The aim of this study was to determine if a single administration of dinoprost tromethamine before each test enhances sexual behaviour in inexperienced rams, and if the possible effect is maintained after the rams gain sexual experience. The study was conducted in northeaster Mexico during autumn (breeding season). The study was performed with 26 Saint Croix rams (16.1 ± 1.1 months old). Rams were allocated to two treatments, which were subjected to 15 tests with 2 restrained non-oestrous ewes. While rams from one group (group DIN) received a single dose of dinoprost (10 mg im, Lutalyse, Zoetis) immediately before the test, the other rams remained untreated (group CON). Sexual behaviours were recorded during 5 min. The data were analysed with a mixed model that included the treatment, number of test and their interaction as main effects, and the individual as a random effect. DIN rams displayed less ano-genital sniffings (6.6 ± 0.8 vs 9.7 ± 0.8, P = 0.007), matings (0.11 ± 0.05 vs 0.29 ± 0.05, P = 0.03), and had a lower mating/total mounts ratio (0.05 ± 0.03 vs 0.16 ± 0.03, P = 0.006) than CON rams. There were no other treatment effects, but there were significant effects of time and interactions between treatment and time in all the behaviours. Overall, administration of a single dose of dinoprost before testing did not have positive effects in the development of rams' sexual behaviour, and even, might have negative effects. However, it should be considered that in this study only one prostaglandin analogue, one dose of this analogue, administered immediately before the tests was used, so more studies involving other analogues, doses, and/or regimes of administration should be done.

Administering an additional prostaglandin F2α injection to Bos indicus beef cows during a treatment regimen for fixed-time artificial insemination.

Two experiments were conducted to evaluate if an additional prostaglandin F2α (PG) injection during an estradiol-based estrous synchronization treatment regimen affects pregnancy rates resulting from fixed-time artificial insemination (FTAI) in Nelore cows. In Experiment 1, 1039 cows were administered estradiol benzoate and an intravaginal progesterone releasing device (CIDR) on d -11, an injection of PG on d -4, with CIDR removal and administration of estradiol cypionate and eCG occurring on d -2, and FTAI on d 0. Cows were administered an additional injection of PG (PG2) or saline (PG1) on d -2. Percentage pregnancy per FTAI on d 30 was greater (P = 0.01) in cows of the PG2 than PG1 group (54.5 % and 46.6 %, respectively). In Experiment 2, there was use of the same treatment regimen for estrous synchronization of 934 cows as that for Experiment 1 followed by FTAI, with there being diagnosis of whether cows had or did not have a corpus luteum on d -4. Response to estrous synchronization, largest follicle diameter at FTAI, and pregnancy per FTAI were greater (P ≤ 0.05) in cows of the PG2 than PG1 group with a body condition score (BCS) < 5.0 at FTAI (81.2 % and 72.6 %, 11.9 and 11.2 mm, 55.5 and 45.6 %; respectively). These treatment responses did not differ (P ≥ 0.18) in cows with BCS ≥ 5.0. Collectively, results indicate that treatment with PG2 increased pregnancy per FTAI in B. indicus cows deficient in body energy reserves, by enhancing follicle development and estrous synchronization response.

Decreasing the dose of equine chorionic gonadotropin does not affect ovarian or pregnancy responses of purebred taurine and crossbred beef heifers.

In this study there was evaluation of effects of different doses of equine chorionic gonadotropin (eCG: 200, 300, or 400 IU) administrated at progesterone (P4) plus estradiol-based timed AI (TAI). A total of 1080 heifers were included in the study. There was insertion of the intravaginal P4-device plus administration of 2 mg of estradiol benzoate IM. On D7, 12.5 mg of dinoprost tromethamine IM was administered and on D9, the P4 insert was removed and 0.5 mg of estradiol cypionate IM was administered. Heifers were categorized according to Reproductive Tract Status (RTS; 1-5) and were assigned to one of three treatments: 200 IU (n = 387), 300 IU (n = 357), or 400 IU (n = 336) of eCG. Estrous occurrence was evaluated at TAI 48 h later (D11). A subset of heifers (n = 213) had the largest follicle (LF) evaluated on D9 and on D11, and the formation of a new CL evaluated on D18.There was no effect of eCG treatment on LF on D11 (P = 0.79), occurrence of estrus (P = 0.92), and pregnancy at 30 days after AI (P/AI; 52.2%, 49.8%, and 51.5% for 200 IU, 300 IU, and 400 IU, respectively; P = 0.46). Regardless of the treatment, there was a greater P/AI when heifers had a functional CL, at initiation of the estrous synchronization treatment regimen. It, therefore, is efficacious to reduce the dose of eCG to 300 or 200 IU in purebred taurine and crossbred beef heifers without negative effects on ovarian, estrous or pregnancy responses.

Effect of additional PGF2α dose on pregnancy rate in Nellore females subjected to FTAI / Efeito de dose adicional de PGF2α sobre a taxa de gestação de fêmeas bovinas Nelore submetidas a IATF

This study examined the effect of administering an additional dose of prostaglandin F2 alpha (PGF2α), in a fixed-time artificial insemination protocol (FTAI), on the fertility of female Nellore cattle. Two experiments were carried out: the first (Experiment I) took place in the state of Tocantins and the second (Experiment II) in the state of Pará, Brazil. In Experiment I (E1), 80 cows were used in three treatments (T1, T2 and T3) in which all received the same FTAI protocol. In T1 (n = 29), the cows received 12.5 mg of Dinoprost on day 9; in T2 (n = 28), they received the additional dose on day 10; and in T3 (n = 23; control group), the animals did not receive the additional PGF2α dose. Experiment II consisted of 147 bovine females distributed into two treatment groups, namely, T1 - 72 animals receiving the same protocol as T1 of E1; and T2 - 75 animals receiving the same protocol as T3 of E1. Statistical analysis was performed using SAS software, applying the PROC NPARWAY procedure for E1, and means were compared by the Wilcoxon test at the 5% significance level. In Experiment II, the data were subjected to analysis of variance by PROC GLIMMIX and means were compared by the T test at the 5% significance level. The following pregnancy rates were obtained in Experiment I: T1 - 62.06% (18/29); T2 - 57.14% (16/28); and T3 - 52.17% (12/23), with no significant difference observed between treatments. In Experiment II, pregnancy rate in T1 was 66.67% (48/72), whereas in T2 it was 41.33% (31/75), with a significant difference detected (P < 0.05). An additional dose of PGF2α provides an increase in pregnancy rate in Nellore females.

Objetivou-se avaliar o efeito da administração de uma dose adicional de prostaglandina F2 alfa (PGF2α) em protocolo de inseminação artificial em tempo fixo (IATF) sobre a fertilidade de fêmeas bovinas da raça Nelore. Foram realizados dois experimentos, sendo um (E1) no estado do Tocantins e o segundo (E2) no estado do Pará. No experimento 1 (E1) foram utilizadas 80 fêmeas bovinas distribuídas em três tratamentos (T1, T2 e T3), todos animais receberam o mesmo protocolo de IATF, diferindo no T1 (n=29), que recebeu 12,5 mg de Dinoprost no dia 9, T2 (n=28) recebeu a dose adicional no dia 10 e o T3 (n=23) - Grupo controle, que não recebeu a dose adicional de PGF2α. O experimento 2 (E2) constituído por 147 fêmeas bovinas distribuídas em dois tratamentos. T1: com 72 animais, recebendo mesmo protocolo do T1 do E1. T2: constituído por 75 animais, com protocolo idêntico ao T3 do E1. A análise estatistica foi realizada no programa SAS, sendo no E1 utilizando-se o PROC NPARWAY e as médias comparadas pelo teste de Wilcoxon com nível de significância de 5%. No E2 os dados foram submetidos à análise de variância pelo PROC GLIMMIX e as médias comparadas pelo teste T com nível de significância de 5%. No experimento 1 a taxa de prenhez no T1 foi de 62,06% (18/29), T2 de 57,14% (16/28) e T3 de 52,17% (12/23), não sendo observada diferença significativa entre os tratamentos. No experimento 2 a taxa de prenhez do T1 foi de 66,67% (48/72), enquanto T2 foi de 41,33% (31/75), verificando-se diferença significativa (P < 0,05). A dose adicional de PGF2α promoveu incremento na taxa de prenhez de fêmeas Nelore.

Is prostaglandin F2α administration at the beginning of a progesterone and estradiol-based treatment for FTAI an effective strategy in Bos taurus heifers?

The objective was to evaluate effects of prostaglandin (PG) F2α administration at the beginning of a progesterone and estradiol-based treatment period on ovarian response and pregnancy rate (P/AI) in Bos taurus beef heifers. Heifers were treated with 500 µg of cloprostenol administered: a) in two half-doses (250 µg) at the time of progesterone device insertion and removal (two-PG), or b) in a single dose at the time of device removal (one-PG). In the two-PG group, administration of PG at device insertion resulted in lesser serum progesterone concentrations during the 7-d treatment period (P < 0.05). Additionally, diameter of the follicle from which ovulation occurred was greater, and ovulation occurred earlier in the two-PG compared with one-PG group (P < 0.05). Fixed-time artificial insemination (FTAI) was performed in 3479 heifers with two times for FTAI (48 compared with 54 h from device removal). There was no effect on P/AI percentage for the PG treatment or the time of FTAI. The FTAI at 54 h resulted in a greater P/AI percentage in the one-PG than two-PG group (70.5%, 253/359 and 63.5%, 254/400, respectively; P < 0.05). There were no differences between PG treatments when FTAI was performed at 48 h after device removal. In conclusion, the administration of PG at the time of intravaginal progesterone device insertion results in lesser progesterone concentrations, and an increased size of the follicle from which ovulation occurs, and the time of ovulation is earlier after device removal. The pregnancy rate was not affected by the PG administration at the time of device insertion.

The reused progesterone device has the same effect on short or long estrus synchronization protocols in tropical sheep.

This study aimed to evaluate the effect of progesterone (P4) device reutilization in long and short protocols for transcervical timed artificial insemination (TAI) in Santa Inês ewes. A total of 275 multiparous lactating ewes were blocked according to body weight (BW, 49.1 ± 7.3 means ± SE), body condition score (BCS, 2.9 ± 0.4; scale of 1-5), and days postpartum (50 ± 8.2 days), and allocated to one of the treatments. The treatments were arranged in a factorial design, in which the factor 1 was the P4 device type (new or a device of 0.3 g of P4 previously used by 11 days), and the factor 2 was the short or long TAI protocol (P4 device remained by 7 or 11 days, respectively). At device removal, all ewes received 300 IU eCG and 6.70 mg of Dinoprost tromethamine. After TAI protocol, ewes remained with ram by 21 days. There was no interaction between factors in any variables. Ewes that received a new P4 device delayed (P = 0.05) to show estrus compared with ewes receiving a previously used P4 device, but it did not affect pregnancy rate. The long protocol tended to increase pregnancy rate compared with short protocol (33% vs. 24%, respectively; P = 0.07). However, the pregnancy rate at the end of reproductive period was similar in both groups (about 84%). Thus, the use of long protocols tended to improve reproductive performance, and the reused P4 device did not affect pregnancy rate.

Presynchronization by induction of a largest follicle using a progesterone device in GnRH-based-ovulation synchronization protocol in crossbred dairy cows.

The objective was to compare the fertility of dairy cows using a presynchronization protocol by induction of a largest follicle using a progesterone intravaginal device prior to an Ovsynch protocol (P4synch) with the Double-Ovsynch in lactating dairy cows. Lactating Bos indicus x Bos taurus crossbred cows (n = 440) were randomly allocated to one of two treatments: (I) Double-Ov (n = 228), GnRH (D-17), PGF2α 7 days later (D-10) and GnRH 3 days later (D-7) followed by an Ovsynch protocol 7 days later (GnRH on D0, PGF on D7, GnRH on D9); (II) P4synch (n = 212), insertion of a sustained release progesterone intravaginal device (D-10), 10 days later (D0) an Ovsynch protocol was initiated (GnRH on D0, PGF on D7, GnRH on D9) with progesterone device withdrawal on Day 7. All cows were artificially inseminated (TAI) 16 h after the second GnRH of the Ovsynch protocol and pregnancy diagnosis was performed by transrectal ultrasonography 30 and 60 days after TAI. A subset of cows (n = 52 for Double-Ov and n = 50 for P4synch) ultrasonography was performed on days 0, 7, 9 and 24 of the experimental period. There were no differences among treatments on presynchronization rate [presence of a follicle>12 mm on D0, Double-Ov 94.2% (49/52) and P4synch 92.0% (46/50); P = 0.66], follicular diameter on the 1st GnRH (Double-Ov 17.2 ±â€¯0.7 mm e P4synch 18.6 ±â€¯0.9 mm; P = 0.28), ovulation rate to the 1st GnRH [Double-Ov 86.3% (44/51) and P4synch 81.2% (39/48); P = 0.50], synchronization rate [presence of a follicle>12 mm on D9; Double-Ov 84.6% (44/52) and P4synch 86.0% (43/50); P = 0.84], follicular diameter on the 2nd GnRH (Double-Ov 17.5 ±â€¯0.6 mm and P4synch 18.0 ±â€¯0.5 mm; P = 0.48), ovulation rate to the 2nd GnRH [Double-Ov 90.9% (40/44) and P4synch 86.0% (37/43); P = 0.48] and CL diameter on D24 (Double-Ov 27.9 ±â€¯0.7 mm and P4synch 29.4 ±â€¯0.9 mm; P = 0.19). Corpus luteum presence on D0 was different (P = 0.03) among treatments [Double-Ov 57.7% (30/52) and P4synch 36.0% (18/50)]. There was no difference (P = 0.85) among the pregnancy per AI on day 30 [Double-Ov 39.0% (89/228) and P4synch 40.1% (85/212)], on day 60 [Double-Ov 34.8% (79/227) and P4synch 38.7% (82/212); P = 0.41] and pregnancy loss [Double-Ov 10.2% (9/88) and P4synch 3.5% (3/85); P = 0.08]. The presynchronization by induction of a largest follicle using a sustained release progesterone device prior to Ovsynch yielded similar results compared with the Double Ovsynch protocol on follicular development patterns and on the fertility of lactating dairy cows.

Impacts of estrus expression and intensity during a timed-AI protocol on variables associated with fertility and pregnancy success in Bos indicus-influenced beef cows.

This experiment evaluated the impacts of estrus expression and intensity, estimated by physical activity during a timed-AI protocol, on reproductive performance of Bos indicus-influenced beef cows. A total of 290 lactating, primiparous, and multiparous nonpregnant Nelore × Angus cows received a 2 mg injection of estradiol benzoate and an intravaginal progesterone (P4) releasing device (CIDR) on d -11, a 12.5 mg injection of PGF2α on d -4, CIDR removal in addition to 0.6 mg injection of estradiol cypionate and 300 IU injection of eCG on d -2, and timed-AI on d 0. Cows were fitted with a pedometer behind their left shoulder on d -4. An estrus detection patch was attached to the tail-head of each cow on d -2. Pedometer results were recorded on d -2 and 0. Estrus expression was defined as removal of >50% of the rub-off coating from the patch on d 0. Net physical activity during estrus was calculated by subtracting total steps from d -4 to -2 (nonestrus basal activity) from total steps from d -2 to 0 (proestrus + estrus period) of each cow. Cows that did not express estrus were classified as NOESTR. Cows that expressed estrus were ranked by net physical activity; those above the median were classified as HIESTR and the remaining cows as LWESTR. Ovarian ultrasonography was performed on d 0 and 7. Blood was collected on d 0, 7, 20, and 30. Pregnancy status was verified by ultrasonography on d 30. Only data from cows responsive to the estrus synchronization protocol were utilized (NOESTR, n = 59; LWESTR, n = 100; HIESTR, n = 98). Diameter of dominant follicle on d 0, corpus luteum volume on d 7, and plasma P4 concentrations on d 7 were greater (P ≤ 0.05) in HIESTR vs. LWESTR and NOESTR and also greater (P ≤ 0.05) for LWESTR vs. NOESTR. Plasma P4 concentrations on d 0 were greater (P < 0.01) in NOESTR vs. HIESTR and LWESTR and similar (P = 0.93) between HIESTR and LWESTR. Whole blood mRNA expression of myxovirus resistance 2 on d 20 was greater (P ≤ 0.05) in HIESTR vs. LWESTR and NOESTR, and similar (P = 0.72) between LWESTR and NOESTR. Pregnancy rates were less (P ≤ 0.04) in NOESTR vs. HIESTR and LWESTR (52.4%, 68.9%, and 73.5%, SEM = 7.2), and similar (P = 0.57) between HIESTR and LWESTR. Hence, expression of estrus during a timed-AI protocol improved ovarian dynamics and pregnancy success, whereas estrus intensity modulated key biological markers associated with fertility but not pregnancy rates in B. indicus-influenced cows beef cows.