The Cholistani cow is considered one of the milch breeds of Zebu cattle. Despite being heat and tick-resistant, it has not yet gained much popularity among Pakistan dairy farmers due to its long calving interval. This study aimed to understand the basic reproductive physiology of Cholistani cows using sonography and reproductive biotechnologies such as estrus synchronization and timed artificial insemination to improve reproductive efficiency. In experiment 1, six Cholistani cows with mixed parity 3.20 ± 1.30 and weighing 400 kg were selected to monitor ovarian dynamics on alternate days by the same sonographer from the onset of heat through ovulation until the next ovulation. Experiment 2 measured the effect of estrus synchronization methods, controlled internal drug release-gonadotropin-releasing hormone (CIDR-GnRH, n = 31) and Ovsynch (OVS, n = 32) on various reproductive parameters. The mean estrous cycle length was 19.81 ± 0.56 days with two follicular waves. The mean inter-ovulatory interval was 20.80 ± 0.52 days, with a preovulatory follicular size of 13.83 ± 2.37 mm. Estrus response was higher (p > 0.05) in controlled internal drug release (CIDR)-GnRH (93.54%) than in OVS (84.37%) cows. Similarly, ovulation and conception rates were higher in CIDR-GnRH (91.66% vs. 68.42%) than in OVS cows (41.37% vs. 33.33%), respectively. In conclusion, CIDR-GnRH results in a better estrus response, higher ovulation rate, and subsequently greater conception rate than OVS in Bos indicus dairy cows.

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.

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.

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.

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.

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.

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.

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.

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.

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-17β 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-17β 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.