Estrogens improve the pregnancy rate in cattle: A review and meta-analysis.

Estrogens have proven to be effective in bovine estrus induction protocols. Considering the extensive use of these products in large-scale estrus synchronization, the primary objective of the present study was to assess their effects on pregnancy rate (PR) using a meta-analysis approach. A total of 797 papers were screened from three major databases (PubMed, Web of Science, Scopus). Sixty-one studies were eligible for inclusion in the meta-analysis. The pregnancy status (success or failure) at 30 days post-insemination was considered as the effect size data. The odds ratios (OR) of PR were evaluated by considering the effects of estrogens in groups with or without estrogen intervention. The impact of estrogen (including factors such as type, dose, and time of administration) and animal characteristics (such as breed, type, and parity) was taken into account when assessing the effectiveness of estrogen response as PR. The results showed an OR of 1.25 (95% CI: 1.15-1.36; P = 0.000) for PR in animals that received estrogen compared to cattle that did not receive estrogen. Estradiol benzoate (OR = 1.3) and estradiol cypionate (OR = 1.2), with doses ranging from 1 to 3 mg (OR = 1.13-1.7), significantly increased the OR of PR. In terms of PR, beef cattle exhibited a higher odds ratio (OR = 1.4; P = 0.000) compared to dairy cattle (OR = 1.1; P = 0.09). The administration of estrogens in the estrus synchronization protocol significantly improved PR in both artificial insemination (OR = 1.2; P = 0.000) and embryo transfer (OR = 1.3; P = 0.033) programs. In summary, incorporating estrogens into estrus induction protocols led to an enhancement of the OR of PR among cattle.

Treatment of postpartum endometritis induced by multidrug-resistant bacterial infection in dairy cattle by green synthesized zinc oxide nanoparticles and in vivo evaluation of its broad spectrum antimicrobial activity in cow uteri.

Postpartum endometritis significantly affects the health and productivity of cattle, causing significant economic loss that is speculated to exceed billions of dollars annually. Treatment of postpartum endometritis, which is linked to various bacterial infections in the uterus after delivery and has an alarmingly high risk of antibiotic treatment failure for unidentified reasons, represents a great challenge. Several studies have demonstrated that various disease complications, such as multidrug-resistant (MDR) bacterial strains, prolonged infection treatment, and increased mortality risk, have emerged as a result of the extensive use of antibiotics to treat uterine infections and other microbial-related diseases. Recent research has led to the development of zinc oxide nanoparticles (ZnO NPs) that exhibit broad-spectrum antibacterial efficacy against bacterial pathogens, including MDR bacteria, without producing mutants that are resistant to zinc oxide (ZnO). In the present work, we biologically synthesized ZnO NPs from a green natural source of Helianthus annuus seeds for the treatment of endometritis caused by MDR bacterial strains in dairy cattle. We examined ZnO's potential as a substitute antimicrobial agent to treat cow endometritis by testing its ability to sustain potent antimicrobial activity against pathogenic bacteria, including Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), in cow uteri. Among uterine bacteria, ZnO significantly decreased E. coli and S. aureus, which are known pathogenic bacteria within the uterus and achieved a high cure rate that was associated with the induction of estrous and pregnancy. Taken together, our observations of ZnO's broad range of antibacterial activity in-vivo with an animal model and subsequent evaluations of its therapeutic efficacy in cows with endometritis shed light on its potential to be used as a substitute antimicrobial agent for the treatment of uterine illness.

Serum Anti-Müllerian Hormone Levels and Estrous Monitoring of GnRH Agonist Deslorelin-Induced Estrus in Bitches: A Pilot Study.

This study was performed to monitor estrous patterns and, more importantly, changes in anti-Müllerian hormone (AMH) concentrations during the peri-ovulatory period in deslorelin-induced estrous bitches. Healthy anestrous bitches (n = 4) were used. Estrus and ovulation were monitored after deslorelin implantation. Blood samples were collected for analysis of progesterone, estradiol-17ß and AMH concentrations before implantation (day 0) and on days 6, 8, 10, 12, 14, 16, 18, 20 and 22 after implantation. Six days following treatment, all bitches showed estrus signs. Ovulation took place between days 12 and 15. Circulating AMH concentrations varied among bitches from 0.12 to 3.08 ng/mL. However, no significant differences in AMH levels (mean ± SD) were observed between day 0 and days following post-implantation (p > 0.05). There were no significant correlations between AMH and estradiol or AMH and progesterone (p > 0.05). Ultrasonographically, the number of clearly identifiable ovarian follicles was higher before ovulation and the area of ovaries increased after ovulation (p < 0.05). Except for AMH, changes in vaginal cytology, estradiol-17ß and progesterone levels observed in our study were similar to naturally occurring estrus. Large intra- and inter-individual variation in AMH were observed suggesting that AMH is currently not suitable as a canine fertility marker to monitor ovarian response to deslorelin treatment for estrus induction.

Male scent but not courtship vocalizations induce estrus in wild female house mice.

Exposure to males or male urinary scent can induce and accelerate the rate of female estrous cycling in house mice ("Whitten effect"), and this response has been replicated many times since its discovery over 60 years ago. Here, we tested whether exposing female mice to recordings of male courtship ultrasonic vocalizations (USVs) induces estrous cycling, and whether exposure to both male scent and USVs has a stronger effect than to either of these stimuli alone. We conducted our study with 60 wild-derived female house mice (Mus musculus musculus). After singly housing females for 14 days, we monitored estrous stages via vaginal cytology for two weeks while isolated from males or male stimuli. We continued monitoring estrus for two more weeks during experimental exposure to one of four different types of stimuli: (1) clean bedding and background noise playback (negative control); (2) recordings of male USVs (16 min per day) and clean bedding (male USV treatment); (3) soiled male bedding and background noise playback (male odor treatment; positive control); or (4) male USVs and soiled male bedding (male odor and USV treatment). Females were then paired with males to test whether any of the four treatments influenced female reproduction (especially latency to birth). We confirmed that exposure to male odor increased female cycling, as expected, but exposure to recordings of male USVs had no effect on estrus. Females exposed to both USVs and odor went through more cycles compared to controls, but did not differ significantly from exposure to male odor (and background noise). After pairing females with a male, females showing male odor-induced cycling produced their first litter sooner than controls, whereas USVs did not have such an effect. This is the first study to our knowledge to show that male odor induces estrus in wild house mice and to show functional effects on reproduction. Our results do not support the hypothesis that male vocalizations induce female estrus, although we suggest other approaches that could be used to further test this hypothesis.

Simultaneously administration of cabergoline and PMSG reduces the duration of estrus induction in anestrous bitches.

This study designed a protocol that would combine pregnant mare serum gonadotrophin (PMSG) and cabergoline (CAB) to induce estrus in bitches. Twenty clinically healthy adult and anestrous female dogs were randomly assigned into four groups. The first group was treated with 5.00 µg kg-1 CAB until the onset of proestrus or for 25 days. The second group was treated with 20.00 IU kg-1 PMSG for 5 days and 500 IU human chorionic gonadotropin (hCG) on the 5th day. The third group was treated with 5.00 µg kg-1 CAB for 10 days in combination with 20.00 IU kg-1 PMSG for 5 days and 500 IU hCG on the 10th day. The control group received 1.00 mL of normal saline. Ovarian changes were evaluated ultrasonographically, and the estrus cycle phase was examined by vaginal cytology. Respectively, three, three and four bitches showed clinical signs of proestrus in each treatment group. The intervals between treatment and proestrus for each group were 30.00 ± 3.05, 7.67 ± 1.20 and 13.00 ± 1.20 days, respectively. Two weeks after estrus, the progesterone mean was 14.51 ± 6.24, 19.96 ± 17.16 and 19.12 ± 9.26 ng mL-1 for each group, respectively. In ultrasonography examination, the largest follicle was identified at 15.66 ± 1.33, 11.66 ± 2.40 and 8.75 ± 2.17 days after the onset of proestrus and the largest follicle's size was measured 6.50 ± 0.55, 4.83 ± 1.64 and 7.07 ± 1.49 mm for each group, respectively. Although the combined use of CAB and PMSG reduced the duration of treatment, alteration of the duration or PMSG dosage can be helpful to improve the results.

Periovulatory Hormonal Profiles after Estrus Induction and Conception Rate by Fixed-Time AI in Payoya Goats during the Anestrous Season.

Sexual activity in domestic goats is positively influenced by reducing the photoperiod. Various protocols have therefore been developed in goats for the induction and synchronization of estrus during those months in which their sexual activity is reduced. The present observational study evaluates the periovulatory hormonal profile in Payoya goats (n = 24), during a non-favorable photoperiod (i.e., spring), being treated for estrus induction. The treatment comprised the vaginal insertion of sponges impregnated with progestogen (fluorogestone acetate, FGA), together with cloprostenol and equine chorionic gonadotrophin (eCG), 48 h before the end of the treatment. When the treatment ended, the plasma concentrations of the LH, FSH, progesterone and estradiol were determined. The goats were inseminated 46 h after the sponge withdrawal, and a pregnancy diagnosis was carried out 40-45 days after the insemination. Various parameters were monitored, such as the peaks of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and estradiol, and their respective intervals, in reference to the time of the sponge withdrawal. The conception rate was 62.5%, and the kidding rate was 50%. The results record the hormonal release pattern after the estrus synchronization treatment based on the FGA, and the differences between the pregnant and non-pregnant goats. The findings suggest that the LH peak produced after the estrus synchronization treatment, both in terms of the amplitude and the time of increment, is involved in the reproductive failure detected.

Changes in luteinizing hormone pulse frequency and prolactin levels in bitches in response to estrus induction by cabergoline-its cases where it is delayed to induce estrus.

The effect of estrus induction by cabergoline on gonadotropin and steroid hormone responses was examined in anestrous bitches. Eleven beagles were used in the study; seven were included in the estrus induction group and four were included in the spontaneous estrus group. Cabergoline was orally administered to the estrus induction group at 5 µg/kg once daily for four weeks, or until hemorrhagic discharge was detected. The inter-estrus interval in the estrus induction group was significantly shorter than the previous estrus interval. Bitches that showed proestrus within four weeks of treatment showed increased luteinizing hormone (LH) pulse frequency and, subsequently, increased estradiol (E2) levels. Prolactin (PRL) levels declined promptly after treatment, except in one bitch that did not show proestrus during the cabergoline treatment period. There was a significant correlation between the time to proestrus induction and the reduction in PRL levels. A positive correlation was found between the LH levels two weeks after cabergoline administration and PRL reduction. This study demonstrates that an abrupt reduction in PRL is likely to be important for initiation of estrus in bitches. A reduction in PRL indirectly leads to an increase in LH pulse frequency, which regulates follicular development in bitches. However, if the period from the end of the previous estrus to the cabergoline treatment is short, it may take some time to show proestrus without increasing E2 levels, even if the LH level increases after cabergoline administration.

Does Size Matters? Relationships among Social Dominance and Some Morphometric Traits upon Out-of-Season Reproductive Outcomes in Anestrus Dairy Goats Treated with P4 + eCG.

The possible role of the social rank (R) (i.e., low-LSR, middle-MSR, or high-HSR) in anestrus goats exposed to a P4 + eCG (D) (i.e., 100 or 350 IU) estrus induction protocol (EIP) was evaluated. Goats (Alpine-Saanen-Nubian × Criollo; n = 70; 25° North) managed under stall-fed conditions were all ultrasound evaluated to confirm anestrous status, while the social rank was determined 30 d prior to the EIP. The response variables included estrus induction (EI, %), duration of estrus (DUR, h), ovulation rate (OR, n), live weight (LW, kg), thoracic perimeter (TP, cm), thoracic diameter (TD, cm), body length (BL, cm), height at withers (HW, cm), beard length (BEA, cm), compactness index (COM, cm), and anamorphosis index (ANA, cm), as affected by R, D, and the R × D interaction were evaluated, while the correlation coefficients among reproductive and morphometric variables were quantified. An R × D interaction (p < 0.05) affected the response variables EI, DUR, and OR. While the largest (p < 0.05) EI% occurred in the HSR goats, irrespective of eCG (i.e., 100 or 350 IU), both the shortest estrus duration (DUR, h) and the lowest ovulation rate (OR, n) occurred in the LSR + D100 combination, with no differences among HSR and MSR either with D100 or D350. Regarding the LW and morphometric response variables, (i.e., LW, TP, TD, BL, HW, BEA, COM, and ANA) all of them favored either the HSR and MSR groups, with the lowest phenotypic values occurring in the LSR-goats. The EI% was observed to be positively correlated (p < 0.05) with DUR (0.71), LW (0.28), TP (0.31), TD (0.34), BL (0.33), HW (0.35), COM (0.23), and ANA (0.23). While DUR was correlated (p < 0.05) with TP (0.26) and ANA (0.24), OR demonstrated no-correlation (p > 0.05) with any response variable, either reproductive or morphometric. As expected, LW had high correlation coefficients (p < 0.01) with TP (0.86), TD (0.88), BL (0.82), HW (0.75), BEA (0.51), COM (0.97), and ANA (0.75). In general, the morphometric variables as a whole demonstrated important correlation coefficients among them (p < 0.01), ranging from 0.38 up to 0.84. To estimate the importance of the morphometric differences between social rank upon estrus induction, a principal component (PC) analysis was performed based on the correlation matrix derived from the corporal measurements. The PC1 and PC2 explained 70.3% and 17.6% of the morphometric variation, respectively. The PC1 was a measure of the goat size (i.e., small, medium, large) and its association with estrus occurrence was evaluated using a logistic regression model; the bigger the goat, the increased probability of being in estrus, by up to five times compared to small goats. Our results confirm that the higher social ranked, larger goats amalgamated some fundamental factors to be successful: aggressiveness, primacy to food access, augmented live weight, and corporal size; all of these were able to modulate out-of-season reproductive success in crossbred dairy goats subjected to an estrus induction protocol and managed under stall-fed conditions in Northern Mexico.

The Effect of P4 + eCG Estrus Induction Protocol during the Deep and the Transition Anestrous Period on the Reproductive Performance of Crossbred Dairy Goats.

Seasonal reproduction restricts the offering of goat commodities across the year. Therefore, it is crucial to improve diverse strategies to induce the reproductive response in goats during the anestrus stage. The effectiveness of a short P4 + eCG-based estrus induction protocol during both the deep anestrous (March) or the reproductive transition period (June) upon the reproductive performance of crossbred dairy goats was assessed. Adult, anestrous, 24-30-month- old dairy crossbred (Saanen-Alpine-Nubian × Criollo) goats (n = 123) from two commercial herds and 10 sexually active goat bucks were used. Before the trials, the anestrous status of goats was confirmed. Then, goats were randomly allocated into two different experiments. In Exp. 1, we tested the effect of different doses (D) of intramuscular progesterone (P4; 10 or 20 mg + eCG (100 UI)) and type of breeding (TB), natural mating (NM), or artificial insemination (AI), on two commercial goat herds (H1 & H2), in March (deep anestrous). In Exp. 2, we evaluated the effect of D (P4; 10 or 20 mg + 100 UI eCG) in goats subjected to NM, and either during deep anestrous (March; M) or transitional anestrous (June; J), in two commercial herds. After breeding, conception and pregnancy were diagnosed with ultrasound scanning. The response variables were estrus induction (EI; %), estrus latency (EL; h), ovulation (OVP; %), ovulation rate (OR; units), fertility (FERT; %), and pregnancy (PREG; %). No differences (p > 0.05) in live weight (LW) and body condition score (BCS) occurred between herds in both trials. In Exp. 1, EI, EL, OVP, OR, FERT, and PREG were affected (p < 0.05) by the H-TB-D interaction, whereas in H1 + P4-20 combination had the highest (p < 0.05) EI, EL, and OVP values. Irrespective of TB, H1 had the largest (p < 0.05) OR, independently of TB or D. Also, the lowest (p < 0.05) OVP occurred in the AI + P4-10 group, while the AI had the lowest (p < 0.05) FERT, irrespective of D. FERT and PREG were two-fold higher (p < 0.05) in NM compared with AI. In Exp. 2, EI, EL, OVP, OR, FERT, and PREG were affected (p < 0.05) by the H-M-D interaction. In general, H2 + P4-10 had the lowest (p < 0.05) reproductive outcomes in March, whereas H1 had the largest (p < 0.05) values in either month. No differences (p > 0.05) between P4 doses occurred for EI, OVP, OR, FERT, and PREG. Yet, the largest (p < 0.05) EL occurred with P4-20 in June. No correlations (p > 0.05) occurred between LW and all the reproductive variables. BCS was positively correlated (p < 0.05) with EI (0.34), OVP (0.44), OR (0.58), and PREG (0.20). Also, positive correlations (p < 0.05) occurred between EI with EL (0.83), OVP (0.80), OR (0.64), and PREG (0.56); EL with OVP (0.58), OR (0.44), and PREG (0.42); OVP with OR (0.79) and PREG (0.70), as well as OR and PREG (0.63). Results of these studies confirm a multidimensional response regarding the effectiveness of P4 + eCG for estrus induction in goats mainly modulated by a specific time within the anestrous season, or even by specific management or a particular environment at the herd level (H1), although quite remarkably independent of the animal's LW or BCS at herd level. Moreover, the best reproductive outcomes occurred with NM in June. The most reproductive variables were similar using either 10 or 20 mg P4 + 100 IU eCG, giving the possibility to lessen the scale in the use of exogenous hormones while obtaining acceptable out of season reproductive response.

Effect of Social Rank upon Estrus Induction and Some Reproductive Outcomes in Anestrus Goats Treated With Progesterone + eCG.

We evaluated the possible role of the social rank [R] (i.e., low-LSR, middle-MSR, or high-HSR) in anestrus goats exposed to a P4 + eCG [D] (i.e., 100 or 350 IU) estrus induction protocol (EIP). Adult, multiparous (two to three lactations), multiracial, dairy-type goats (Alpine-Saanen-Nubian x Criollo goats (n = 70; 25°51' North) managed under stall-fed conditions were all ultrasound evaluated to confirm anestrus status while the R was determined 30 d prior to the EIP. The variables of estrus induction (EI, %), estrus latency (LAT, h), estrus duration (DUR, h), ovulation (OVU, %), ovulation rate (OR, n), corpus luteum size (CLS, cm), pregnancy (PREG, %), kidding (KIDD, %), and litter size (LS, n) as affected by R, D, and the R × D interaction, were evaluated. While OVU and CLS favored (p < 0.05) HSR (96% and + 1.04 ± 0.07 cm), an increased (p < 0.05) LS occurred in D350 vs. D100 (2.06 ± 0.2 vs. 1.36 ± 0.2); neither R nor D affected (p > 0.05; 38.5%) KIDD. However, EI, LAT, DUR, OR, and PREG were affected by the R × D interaction. The HSR group had the largest (p < 0.05) EI % and DUR h, irrespective of D. The shortest (p < 0.05) LAT occurred in D350, irrespective of R. While the largest (p < 0.05) OR occurred in HSR and MSR within D350, the HSR + D350 group had the largest PREG (p < 0.05). These research outcomes are central to defining out-of-season reproductive strategies designed to attenuate seasonal reproduction in goats.

Systematic review and meta-analysis of the efficacy of reproductive management practices used to induce resumption of ovarian cyclical activity in anestrous does.

Reproductive management practices that use hormones, sociosexual biostimulation, nutritional management, or abiotic factors are used to induce the resumption of reproduction in anestrous does. However, their overall efficacy remains uncertain; therefore, the identification of evidence-based management recommendations to manipulate anestrous in goats is important. Electronic databases were searched to retrieve reports on studies using interventions based on hormonal, sociosexual, nutritional, and abiotic factors. Only experimental studies in which a group of anestrous does was treated and compared against an untreated group were included. Estrus, ovulation, and pregnancy were primary outcomes, whereas the onset of estrus after treatment, the ovulation rate, and the number of anovulatory days were secondary outcomes. Odds ratio (OR) and mean differences were used to synthesize pooled data, and random effects models were used to calculate them. Seventy studies involving 3974 goats met the inclusion criteria. Unclear risk of bias for random sequence generation and allocation concealment predominated across studies. Pooled data for hormonal, sociosexual, and abiotic interventions showed a significant, though variable, increase in estrus (OR range 7.15-144.80), ovulation (OR range 6.08-56.95), and pregnancy (OR range 3.94-30.8). Hormonal treatments significantly reduced the onset of estrus, whereas abiotic interventions failed to reduce the number of anovulatory days. Secondary outcomes were not assessed in trials using sociosexual approaches. Finally, except for pregnancy, no significant efficacy was observed for studies using nutritional management. In conclusion, reproductive management practices using sociosexual approaches showed the highest efficacy for restoring reproductive activity in anestrous does.

Use of human intravaginal tampon embedded with natural progesterone induces synchronous estrus in Santa Inês ewes / Uso de tampão intravaginal humano embebido com progesterona humana para indução e sincronização de estro em ovelhas Santa Inês

Este estudo avaliou a eficiência de três protocolos de indução de estro síncronizado em ovelhas da raça Santa Inês. Vinte e quatro ovelhas adultas foram equitativamente distribuídas em três grupos, de acordo com ordem de parto, peso corporal (kg) e escore da condição corporal. As ovelhas receberam implante vaginal de progesterona natural por seis dias mais 37,5µg de d-cloprostenol laterovulvar e 300UI de eCG i.m., 24 horas antes da remoção do dispositivo. Ovelhas controle receberam CIDR330mg de progesterona, e as demais receberam dispositivo absorvente intravaginal humano, tamanho mini, embebido com 200 (OB200) ou 400mg (OB400) de progesterona. Coletas de sangue foram feitas nos momentos D0 (antes da inserção dos dispositivos), D0+6h e diariamente, até um dia após retirada do dispositivo (D7). A progesterona (ng/mL) foi semelhante (P>0,05) em todos os tratamentos ao longo do período experimental, exceto no dia da remoção do dispositivo, quando as ovelhas controle (2,5±0,3) tiveram progesterona superior (P<0,05) às ovelhas OB200 (0,6±0,1) e OB400 (1,2±0,4). O percentual de animais em estro (100,0, 62,5 e 100,0%) foi semelhante (P>0,05) e o intervalo para o estro (46,3±3,9a, 26,4±4,5b e 31,2±5,8a,b) foi diferente (P<0,05) entre os animais dos grupos controle, OB200 e OB400, respectivamente. A taxa de concepção das ovelhas foi de 50,0% (4/8) para cada grupo (P>0,05). Dispositivos humanos e fonte de progesterona podem ser usados para induzir o estro sincronizado em ovelhas Santa Inês.(AU)

Effect of different dosages of PG-600 on ovulation and pregnancy rates in ewes during the breeding season.

This study compared the reproductive effects of different dosages of PG-600 (Intervet/Merck Animal Health, Madison, NJ) during the breeding season of ewes. PG-600 is a single-dose injectable product labeled for estrous induction in swine, containing equine chorionic gonadotropin (80 IU/mL) and human chorionic gonadotropin (40 IU/mL). PG-600 is routinely used off-label for out-of-season estrous induction in sheep. However, at the most common dose administered to ewes (5 mL), PG-600 is likely to overstimulate the ovaries, resulting in reduced pregnancy rates. Following estrous synchronization with intravaginal progesterone and cloprostenol, Polypay ewes were treated with 5 mL PG-600 (T1; n = 8), 1.5 mL PG-600 (T2; n = 8), or 5 mL saline (C; n = 8) and then mated to rams. Jugular vein samples were collected prior to the PG-600 injection (0 hr) and at 2, 4, 8, 12, and 24 hr after injection. Serum estradiol-17ß was determined by chemiluminescence and among groups using repeated measures analysis of covariance. Ovulation and pregnancy rates were determined by transrectal ultrasonography and compared by one-way ANOVA and chi-square, respectively. Estradiol-17ß concentrations were greater in T1 compared to T2 and C (P < 0.001). Ovulation rate was greater (P < 0.001) but pregnancy rate was lower (P < 0.001) in the T1 compared to C and T2. These data confirm that a 5 mL dose of PG-600 administered to ewes during the breeding season overstimulates the ovaries, which may then reduce fertilization or embryo survival. Future research will focus on the effects of different dosages of PG-600 on pregnancy rate of ewes during the nonbreeding season.

Arterial ovarian blood flow in the periovulatory period of GnRH-induced and spontaneous estrous cycles of bitches.

The aim of this study was to compare arterial blood flow determined by repeated Doppler sonographic examinations in the periovulatory period in GnRH-induced and spontaneous estrous cycles of bitches. The study was performed on 10 bitches with GnRH agonist implant-induced estrus (Suprelorin® containing 4.7 mg deslorelin), and 10 bitches with spontaneous estrus (group B), which served as a control. Pulsed-wave Doppler ultrasonography was performed daily from the beginning of proestrus until early metestrus. The ovarian blood flow parameters in the left and right ovarian arteries, including systolic peak velocity (SPV), end diastolic velocity (EDV) and resistance index (RI), were measured. Obtained outcomes from the period of three days before ovulation (Days -3, -2, -1), ovulation (day 0) and three days after ovulation (Days +1, +2, +3) were evaluated statistically. There were no differences between blood flow variables in the bitches with spontaneous and induced cycles recorded on the same day. The values of SPV and EDV were higher (p < 0.05) on days -1, 0, +1, +2 and + 3 than the velocimetric variables collected on days -3 and -2. Then, a significant increase in blood flow was detected one day before ovulation and was continued during next 3 days (p < 0.05). In contrast, the mean RI values remained constant during the entire experiment or even showed a slight declining trend in both groups (p > 0.05). We concluded that arterial blood flow measured around ovulation does not allow for precise detection of exact ovulation time in bitches in induced and spontaneous cycles.

Estrous Cycle Manipulation in Dogs.

Since 1939, scientists have studied estrous cycle manipulation in dogs resulting in more articles published in this field that any other area of canine reproduction. Estrous cycle manipulation in dogs must be safe and reliable. Dopamine agonists, gonadotropin-releasing hormone agonists, and gonadotropins are hormones that have been used for estrus induction in bitches but each treatment has advantages and disadvantages. Despite widespread availability of these medications throughout the rest of the world, there are no drugs currently labeled for canine estrus induction in the United States.

Response to estrus induction with abortion treatment in microminipigs on different days after insemination.

In microminipigs, estrus induction with abortion treatment, which is typically performed between 25 and 40 days after mating, is not always successful. Thus, the authors hypothesized that it may be more difficult to induce estrus by treating microminipigs approximately 40 days after mating. Accordingly, in this study, estrus induction was performed with abortion treatment in four microminipigs as follows: 0.3 mg of cloprostenol, a prostaglandin F2-alpha analog, was administered (day 0); after 24 h, 0.15 mg of cloprostenol and 250 IU of equine chorionic gonadotrophin were administered intramuscularly and simultaneously (day 1); after 96 h, 120 IU of human chorionic gonadotropin was injected intramuscularly (day 4). These treatments were compared at two different stages of pregnancy: early treatment (26.5 ± 0.7 days) and late treatment (38.3 ± 0.8 days). In the early treatment, all four microminipigs exhibited estrus on day 5, whereas in the late treatment, estrus was observed clearly in only two pigs on day 6 and slightly in 1 pig on day 10, whereas it was unclear in 1 pig. These results suggest that it is difficult to induce estrus with abortion treatment in microminipigs at approximately 40 days after mating.

Parâmetros reprodutivos após indução de estro com diferentes intervalos de permanência do dispositivo vaginal em cabras Toggenburg acíclicas / Reproductive parameters after induction of estrus with different ranges of the vaginal device in acyclic Toggenburg goats

Este estudo objetivou avaliar o comportamento sexual e a dinâmica ovulatória de cabras da raça Toggenburg após a indução do estro com dispositivo intravaginal de progesterona durante seis, nove e 12 dias de permanência. No momento da inserção do dispositivo e 24 horas antes da retirada do dispositivo, foi administrado 5mg de dinoprost e 200UI de eCG, respectivamente. A dinâmica ovulatória foi acompanhada por ultrassonografia a cada oito horas, enquanto o estro foi observado a cada 12 horas. Todas as cabras apresentaram estro. O intervalo da retirada do dispositivo ao início do estro foi de 29,5 ± 9,6 para G6dias; 34,0 ± 6,0 e 32,4 ± 7,7h, G9dias e G12dias, respectivamente. Igualmente, foi encontrada diferença (P<0,05) entre o G6dias e os outros grupos. A duração do estro diferiu (P<0,05) entre o G6dias (36,0 ± 12,6) e os outros dois grupos (G9dias: 31,2 ± 14,3; G12dias: 33,4 ± 8,6). A taxa de ovulação (81%; 89,5% e; 71,4%), intervalo da retirada do dispositivo à ovulação (50,5 ± 11,4; 46,3 ± 5,9 e; 46,7 ± 8,3), diâmetro do maior folículo (6,6 ± 0,3; 6,6 ± 0,9 e; 6,9 ± 0,8) diâmetro do segundo maior folículo (6,4 ± 0,7; 6,6 ± 0,8 e; 6,8 ± 0,6) e o número de folículos ovulados (1,5 ± 0,6; 1,7 ± 0,6 e 2,0 ± 0,9) para G6dias, G9dias e G12dias, respectivamente, foram semelhantes (P>0,05). Todos os protocolos foram eficientes em induzir o estro sincronizado em cabras da raça Toggenburg, trabalhando em conjunto com a eficiência reprodutiva e produtiva desses animais.(AU)

This study aimed to evaluate the sexual behavior and the ovulatory dynamics of Toggenburg goats after induction of synchronized estrus by an intravaginal progesterone device for six, nine and twelve days. At the device insertion and 24 h before the device removal, 5mg of dinoprost and 200 UI of eCG was administered, respectively. The ovulatory dynamics was assessed by ultrasound every 8 h, while the sexual behavior was observed every 12 h. All goats showed estrus. The intervals from device removal to estrus were 29.5 ± 9.7, 34.0 ± 6.0 and 32.4 ± 7.7h to G6days, G9days and G12days, respectively. Iqually, it was found difference (P<0.05) among G6days and the other groups. The duration of estrus differed (P<0.05) among the G6days (36.0 ± 12.6) and the other two groups (G9days: 31.2 ± 14.3; G12days: 33.4 ± 8.6). The ovulation rate (81.0%; 89.5% and; 71.4%); the interval from device removal to ovulation (50.5 ± 11.4; 46.3 ± 5.9 and; 46.7 ± 8.3), the diameter of the largest follicle (6.6 ± 0.3; 6.6 ± 0.9 and; 6.9 ± 0.8), diameter of the second largest follicle (6.4 ± 0.7; 6.6 ± 0.8 and; 6.8 ± 0.6) and the number of ovulations (1.5 ± 0.6; 1.7 ± 0.6 and; 2.0 ± 0.9) for G6days, G9days and G12days, respectively, were similar (P>0.05). All treatments were effective for the induction of synchronized estrus in Toggenburg goats, working jointly with the reproductive and productive efficiency of these animals.(AU)

The Clinical Follow-Up of Estradiol Benzoate Priming During Induction of Estrus With Cabergoline in Dogs.

Induction of estrus is used to improve reproductive efficiency of female dogs. In this study, 11 adult healthy female dogs were selected at anestrus stage. The dogs were assigned to treatment (6 dogs) and control groups (5 dogs). Single dose of estradiol benzoate was injected in treatment group at day 0 (0.01mg/kg, IM). Dogs in both groups received cabergoline (5µg/kg orally) from day 7 to the onset of proestrus. Vaginal cytology and blood samples were taken twice a week during study. Average time to the onset of proestrus was 10.33 ± 4.2 and 15 ± 7.5 days in the treatment and control groups, respectively (P = .08). The differences in time to the onset of estrus phase in the treatment group (14.67 ± 5.9 days) and control group (18.67 ± 10.8 days) were significant (P < .05). The average length of proestrus phase in treatment and control groups was 5.33 ± 2.2 and 8 ± 4.6 days, respectively and their differences were significant (P < .05). Average length of estrus phase in treated dogs with estradiol benzoate was 8.57 ± 3.5 days but it was 8 ± 4.6 days in control group (P > .05). Administration of cabergoline caused significant decrease of prolactin concentration in both groups (P < .01). The difference in serum prolactin concentration between treatment and control was not significant. The effect of cabergoline on serum prolactin concentration was not affected by administration of estradiol benzoate in treatment group (P > .05). As a result, administration of estradiol benzoate 1 week before cabergoline improved induction and synchronization of estrus in dogs.

Ovulatory and fertility response using modified Heatsynch and Ovsynch protocols in the anovular Murrah buffalo (Bubalus bubalis).

We studied the effect of modified Heatsynch and Ovsynch protocols on the ovulatory response (OR), estrus induction rate (EIR) and conception rate (CR) in the anovular postpartum Murrah buffalo (n = 35). In the modified Heatsynch protocol (Group I; n = 12), buffaloes were given two GnRH at 2 h interval on treatment day 0, PGF (PGF2α) on day 7 and estradiol (E2) 1 mg on day 8. Two FTAI were done at 20 h intervals after E2 administration. In the modified Ovsynch protocol (Group II; n = 15), GnRH was given on day 0, 7 and 16 with a PGF on day 14. Two FTAI were done; one at last GnRH and the other 20 h later. Group III served as untreated negative control (n = 8). During the treatment, ovarian changes were monitored by transrectal ultrasonography and plasma progesterone (P4) and E2. Administration of two GnRH at 2 h interval neither increased the OR nor strengthened the subsequent P4 priming. Interestingly, in group I, none of the buffalo ovulated to E2 though the EIR was 100% indicating the occurrence of behavioral, but not ovulatory estrus. Administration of GnRH 7 day prior to the commencement of Ovsynch protocol (Group II) did not improve the CR (21.4%), though the OR was 71.4%. No significant difference was found in the diameter of largest follicle between the ovulated and non-ovulated buffalo in response to GnRH suggesting that follicle of ≥9.5 mm is necessary but not sufficient to induce ovulation in the anovular buffalo. In both the protocols, the plasma P4 was higher on day 7 in those buffaloes that ovulated to GnRH. Buffaloes treated with modified Ovsynch regimens were 5.27 times more likely to become pregnant than modified Heatsynch protocol. It is concluded that modified Ovsynch protocol is superior to modified Heatsynch protocol in terms of OR and CR.

Short-term dietary concentrate supplementation during estrus synchronization treatment in beef cows increased IGF-I serum concentration but did not affect the reproductive response.

The objective of this study was to evaluate if short-term dietary concentrate supplementation increased IGF-I serum concentration and resulted in a reproductive response during estrus synchronization treatment in non-lactating beef cows. Thirty non-lactating beef cows (Bos indicus × Bos taurus) were allocated to the same pastureland and fed native tropical grasses as a basal diet. Cows were synchronized using a 7-day CO-Synch plus controlled internal drug release (CIDR) protocol and received fixed time artificial insemination (FTAI). Cows were divided into two groups; the control group (n = 16) received 0.5 kg of concentrate/cow/day, whereas the supplemented group (n = 14) received 4.0 kg of concentrate/cow/day. The period of supplementation was 10 days from the day of CIDR insert to FTAI. The concentration of IGF-I increased (P < 0.05) in the supplemented group, while no significant changes were observed in the control group. Moreover, at the time of insemination, IGF-I serum concentrations were higher in supplemented cows compared with control cows (P < 0.05). Notably, metabolite and insulin concentrations did not differ (P > 0.05) between treatment groups or sampling day. The response to estrus induction, measured as estrus presentation, ovulation rate, and pregnancy rate, was similar between experimental groups (P > 0.05). In conclusion, our results indicated that supplementation with dietary concentrate for 10 days in non-lactating beef cows changed the endocrine milieu, specifically increasing IGF-I serum concentration. However, these endocrine changes did not affect response to estrous induction treatment.