Behavioral Estrus Research Articles

PSIV-15 Economic Impact of a 14-D Cidr Pre-Synchronization on Cost Per Pregnancy in Holstein Heifers

Abstract Feed cost is the largest expense in developing dairy heifers with improved reproductive performance there is opportunity to reduce costs through decreasing days on feed to first calving. The objective of this study was to compare the economic impact of a 14-d CIDR pre-synchronization protocol to no pre-synchronization in Holstein heifers during an 84-d breeding period. Heifers were divided in two treatment groups 1) 14-d CIDR pre-synchronization (pre-synch; n = 20) and 2) control (n = 16). Heifers in the pre-synch treatment received a CIDR on d -30 which were removed on d -16. On d 0 (day of breeding eligibility) heifers in both groups were administered PGF2α and an Estrotect patch for estrus detection. On d 0, body weight of the heifers was estimated using a heart girth tape for large breeds. Estrotect patches were assessed once daily in the morning and heifers with ≥ 50% of the patch scratched received AI the same morning with Holstein sexed semen. After AI, heifers received a new Estrotect patch to facilitate return to estrus. Heifers that failed to express behavioral estrus within 14 d after PGF2α administration received another dose of PGF2α every 14 d until the first behavioral estrus was observed. Approximately thirty days after AI, heifers were subjected to ultrasonography of uterine contents for pregnancy diagnosis, and re-confirmed pregnant at ~60 d. Heifers diagnosed open received an injection of PGF2α and a new Estrotect patch. Partial budget analyses utilize these prices: feed cost ($1.75/heifer/day), PGF2α ($3.29/dose), needle and syringes ($0.12/per injection), Estrotect patch ($1.20/unit), AI procedure ($10.00/AI), semen ($35.00/straw), CIDR ($16.60/unit), pregnancy diagnosis ($5.00/heifer), overall labor ($0.41/heifer/day), and extra labor for CIDR group ($1.25/heifer). The partial budget was calculated per heifer and per pregnant heifer by charging pregnant heifers the cost of the remaining open heifers at the end of the 84-d period. There was no difference (P ≥ 0.26) in weight at d 0 (399.9 ± 15.2 vs 398.4 ± 15.8 kg), age at d 0 (371.6 ± 8.7 vs 371.5 ± 8.9 d), days to first AI (6.85 ± 2.28 vs 6.27 ± 2.50 d), days to pregnancy (20.55 ± 7.52 vs 14.09 ± 8.22 d), average number of services (2.10 ± 0.30 vs 2.06 ± 0.34 AI/heifer), average number of services to pregnancy (1.56 ± 0.24 vs 1.50 ± 0.27 AI/heifer), proportion of heifers receiving AI in the first 7 d (85.0 ± 8.0 vs 68.8 ± 11.6 %), proportion of heifers pregnant at first service (50.5 ± 12.5 vs 56.4 ± 13.5 %) and final pregnancy rates (80.0 ± 8.9 vs 75.0 ± 10.8 %) for pre-synch and control, respectively. Average cost per animal ($ 194.50 ± 30.27 vs 170.44 ± 33.85) and average cost per pregnancy ($ 243.12 ± 37.16 vs 206.95 ± 42.91) were not statistically different (P ≥ 0.53) between pre-synch and control, respectively. In summary, the use of a 14-d CIDR pre-synchronization did not have a significant economic impact on the performance of Holstein heifers during an 84-d breeding period.

PSIII-12 The Effects of PGF2 and PGF2 Plus Gnrh on Estrous Behavior and Pregnancy Outcomes in Dairy Goats

Abstract Artificial insemination protocols depend on efficient behavioral estrus detection and insemination time in dairy goats. Here we examined the effects of two synchronization protocols, prostaglandin F2α (PGF2α; protocol 1) and PGF2 plus gonadotropin-releasing hormone (GnRH; protocol 2) on estrus behavior, body temperature, pulse frequency, pregnancy protein B (PPB) concentrations, and pregnancy rates in Alpine and Saanen goats. Forty does (3.9 ± 0.28 year) were divided into two groups (20 each) with 10 Alpine and 10 Saanen females in each group. In protocol 1 goats were injected with 10 mg/goat PGF2α on day 0 and 11. In protocol 2, each goat was injected with 10 mg PGF2α on day 0, and 43 µg GnRH on day 9 and then 10 mg PGF2 α on day 11. Estrus signs were detected 24 to 36 hours after the second dose of PGF2α. Body temperature and pulse frequency were recorded on days 11, 12, 13, and 14 after the second dose of PGF2α. Goats that showed estrus signs were naturally bred with the same breed mature buck. Blood samples were collected on days 28, 35, and 42 post-breeding (PB) to assess PPB concentrations, and ultrasonography was performed on day 50 (PB) to confirm pregnancy. The percentage of female showed estrous was higher in protocol 1 than in 2 (70% vs. 60%). Irrespective of the breed, rectal and vulval temperature was higher in the protocol 2 than 1 at day 11 after PGF2 α injection; however, it was the opposite at days 12, 13, and 14. However, the pulse frequency was greater (P < 0.05) in protocol 2 at all the time point. Pregnancy rates were 71.4% and 75.0% for protocols 1 and 2, respectively. Irrespective to the synchronization protocols, the pregnancy rates were greater (P < 0.05) in Alpine than Saanen goats. In conclusion, both PGF2 and PGF2-GnRH protocols were effective in synchronizing estrus in Alpine and Saanen goats, with minor differences in estrus response rates and pregnancy outcomes. Breed-specific variations were observed within the protocols, indicating a potential influence of breed on the efficacy of estrous synchronization. This study contributes valuable insights to goat breeding programs and promotes more efficient and sustainable livestock management practices.

Comparative evaluation of estrus synchronization protocols on reproductive performance and estrus behavior in Barbados Black Belly sheep.

Estrus synchronization of ewes has been accomplished using several protocols with various degrees of success in improving reproductive efficiency and obtaining the most effective protocol used in sheep farming. This study aimed to compare the effectiveness of three treatment protocols and to record the intensity and duration of estrus signs and pregnancy rate in Barbados Black Belly (BBB) sheep. Thirty-two primipara BBB ewes aged 18-24 months were equally divided into three treatment groups. T1: the ewes were injected intramuscularly with 2 mL Lutalyse (PGF2α) (10 mg) on days 0 and 10. T2: 1 mL Fertiline (50 μg; Gonadorelin acetate) on day 0 and 2 mL lutalyse (10 mg) on day 7. T3: 1 mL fertiline (50 μg) on day 0, 2 mL lutalyse (10 mg) on day 7, and 1 mL Fertiline (50 μg) on day 9. Estrus response was assessed using naturally mating rams and ewes. Pregnancy was determined using ultrasonography between 55 and 80 days after the last hormonal injection. The following estrus signs were noted: Swollen vulva, mucus discharge, sniffing, excitement, loss of appetite, mounting, and rapid tail movement. Of the expressed signs, swollen vulva was most frequent, whereas loss of appetite and mucus discharge were the least overt signs recorded. The estrus response (%), onset (%), and duration (h) in ewe synchronization of the three treatment protocols were 100%, 58.3 ± 23.4%, and 48.0 ± 18.2 h (T1), 100%, 61.7 ± 41.2%, and 45.0 ± 27.0 h (T2), and 37.5%, 32.1 ± 1.7%, and 29.2 ± 1.25 h (T3), respectively. The pregnancy rates were 87.5%, 87.5%, 37.5%, and 50.0% in T1, T2, T3, and T4, respectively. Prostaglandin F2α+PGF2α and GnRH+PGF2α synchronization protocols were more effective in the fertilization of BBB ewes with better expression of estrus signs compared with the GnRH+PGF2α+GnRH (OVS) protocol.

Transcervical artificial insemination in the brown brocket deer (Subulo gouazoubira): a promising method for assisted reproduction in deer

The present study aimed to test the efficiency of transcervical artificial insemination techniques with cervical immobilization (TCAI-CI) or cervical traction (TCAI-CT), associated or not with the use of oxytocin (OT) as a protocol for cervical dilation, in the brown brocket deer (Subulo gouazoubira). The study was carried out in a crossover design using four adult females in two replicates with an interval of 60 days. Estrus was synchronized with oral melengestrol acetate (MGA) associated with estradiol benzoate and sodium cloprostenol. TCAI techniques were performed from 18 to 24 h after estrus onset. All females received either an i.v. application of 50 IU of OT (G-OT, n = 4) or 1 mL of saline solution (G-Control, n = 4) 20 min before the TCAI procedure. The TCAIs were performed using frozen-thawed semen motility 40%, vigor 3, acrosome integrity 87%, membrane integrity of 95% and 13% of total post-thaw defects from the same batch. Behavioral estrus was observed in 100% of the females, in both replicates. It was achieved a 50% (4/8) success of cervical transposition with semen deposition in the uterine. Regarding inseminations, most of them (87.5%) were performed using the TCAI-CT technique, and the overall conception rate was 50%. Cervical transposition times (< 1 min) and TCAI procedures (~ 17 min) were considered satisfactory. Thus, the performance of the TCAI-CI and TCAI-CT techniques was successful, regardless of using OT as a cervical dilation protocol. This procedure is proposed as a method of choice for artificial insemination with greater applicability in different conservation centers, compared to more advanced reproductive biotechniques, and with a favorable impact on the conservation of deer species.

Management of pregnancy failure in cows with vaginal stimulation and hormone therapy

The focus of this study is to improve the pregnancy rate of cattle using different interventions with the analysis of associated risk factors. A total of 180 cows with pregnancy failure after one insemination were selected, which showed normal oestrous behaviour and vaginal mucus discharge. The animals were divided into six groups: A [control: with only Artificial Insemination (AI)]; B [penis-like device (PLD) used after AI]; C [intramuscular injection (im) of 2 ml prostaglandin-F2α at day 7 of the oestrous cycle and AI at observed oestrus], D [AI at natural oestrus followed by 2.5 ml GnRH im, repeated 4-6h after AI], group E [As group C and PLD used after AI], group F [as D and PLD used after AI]. The overall pregnancy was 55.6%. Group F had the highest pregnancy rate (70.0%). Higher pregnancy rates were in older animals of more than 4.6 years of age with parity of more than two. A significant correlation was found between age and parity; age and Artificial Insemination Technician (AIT); Body Condition Score (BCS) and breed; Reproductive Health (RH) and AIT. It is suggested that the use of hormonal treatments (with or without PLD) improved the pregnancy rate in cattle.&#x0D; Bangl. vet. 2022. Vol. 39, No. 1-2, 16–25

Pilot study investigating estrus length and estrus behavior in Norwegian Red cattle on a commercial dairy farm.

Norwegian Red has been shown to have high levels of estrus behavior under experimental conditions. However, the estrus behaviors of Norwegian Red cows have not been studied under commercial conditions. A herd of 89 Norwegian Red cows housed in free stalls on concrete, slatted floors, were continuously video monitored for 21 days. Ovarian cyclicity was confirmed in a final study sample group (n = 18) using milk progesterone concentrations. All mounting and standing activities were recorded, and the duration of mount estrus, standing estrus and the differences between these; prestand and poststand, were determined. The cycle stages metestrus, diestrus and proestrus were estimated based on the starting time and ending time of mount estrus. All cows in the final study sample group exhibited the primary estrus sign, 'standing to be mounted' during estrus. Two (11%), eleven (61%) and six (33%) cows exhibited the behavior 'standing to be mounted' during metestrus, diestrus and proestrus, respectively. The number of mounts initiated by individual cows was higher during mount and stand estrus than during the rest of the estrous cycle. This study reports a median duration of mount estrus and stand estrus of 21.0 h (interquartile range (IQR) 15.0 to 27.3) and 14.3 h (IQR 12.0 to 18.8), respectively. The median counts per hour of all mount behaviors were 8.6 (IQR 5.6 to 11.3), 1.51 (IQR 0.3 to 3.8) and 1.7 (IQR 0.8 to 6.0) for standing estrus, prestand and poststand, respectively. This study shows that under commercial conditions the Norwegian Red cow displays a high level of mount and stand activity associated with estrus.

Evaluation of minimally invasive estrus synchronization protocols in brown brocket deer (Subulo gouazoubira)

This study aimed to evaluate minimally invasive protocols for estrus synchronization in the brown brocket deer (Subulo gouazoubira). Females were submitted to Latin square design, in different treatments. All females received 0.25 mg of estradiol benzoate on the first day of treatment, concomitant with one of the following sources of progesterone: (1) DIP: an intravaginal progesterone releasing device for eight days, (2) MGA1x: once a day (in the morning) oral dose of 1 mg melengestrol acetate for eight days, (3) MGA2x: twice a day (morning and afternoon) oral doses of 0.5 mg of MGA for eight days, (4) P4LA: a single i.m. administration of 75 mg of long-acting progesterone (P4LA). Eight days after the beginning of each treatment, females received an i.m. administration of 265 µg of prostaglandin (PGF2α; cloprostenol). Treatment efficacy was evaluated by manifestation of behavioral estrus after treatment and concentration of fecal progesterone metabolites (FPM). The time to onset of estrus in treatment P4LA was significantly longer (180 ± 38.9 h) compared to DIP (63 ± 6.6 h), MGA1x (53 ± 14.4 h) and MGA2x (41 ± 10.1 h) (P = 0.008). According to individual baseline FPM and FPM concentration during the days after estrus, the corpus luteum formation was suggested in all females which responded to the treatments (93.75 %). Low synchrony, longer interval between PGF2α administration and onset of estrus suggest that the P4LA dose (75 mg) is too high and not effective for S. gouazoubira. DIP, MGA 1x and MGA 2x, were effective in estrus synchronization.

Postpartum longissimus dorsi muscle loss, but not back fat, is associated with resumption of postpartum ovarian activity in dairy cattle

The objectives of this observational cohort study were to assess the effect of body condition score change, back fat depth change, and muscle diameter change on the time to commencement of luteal activity and first estrus in commercial pedigree Holstein cows. One hundred and 40 of 200 commercial pedigree Holstein cows were enrolled in one dairy herd in Somerset, United Kingdom, over 52 weeks in 2021-22. The herd used 4 automatic milking machines with in-line progesterone measurement capability to determine commencement of luteal activity and time to first estrus. Cows were followed until at least 60 d postpartum and milk progesterone measured daily starting from 10 DIM. Body condition scoring and ultrasound measurements of back fat depth and Longissimus dorsi muscle diameter were performed on cows twice: within 7 d of both calving and 60 DIM. Other explanatory variables assessed included parity, 60-d and 305-d milk yield, and subclinical ketosis (β-hydroxybutryate (βHB) ≥ 1.2mmol/L). Occurrence of clinical disease <60 DIM was forced into all models as a binary variable. Data were analyzed using multivariable cox proportionate survival analyses. Muscle loss was associated with commencement of luteal activity and time to first estrus. A reduction in muscle diameter by 1.5 to 5 mm was associated with the shortest time to the start of luteal activity and first estrus. A reduction in muscle diameter >8 mm was associated with the longest times to luteal activity and first estrus. In addition to being affected by muscle loss, commencement of luteal activity was delayed by subclinical ketosis, clinical disease, and failure to gain body condition to 60 DIM. Cows that had a BCS loss of 0.25 or more between calving and 60 DIM were at least 52 ± 22% less likely to have commenced luteal activity compared with those that gained BCS. Interestingly, cows that had no change in body condition score commenced luteal activity later than those that gained body condition score. Muscle loss was associated with time to first estrus irrespective of clinical disease status. Cows that lost > 8 mm of muscle diameter showed estrus behavior later than cows that lost 1.5 to 5 mm. In conclusion, our findings indicate that extensive muscle loss postpartum was associated with a delayed start to luteal activity and first estrus irrespective of body condition change, clinical disease, and subclinical ketosis. Marginal muscle loss and a gain in body condition, however, were associated with an earlier start to luteal activity and first estrus.

Study of Pose Estimation Based on Spatio-Temporal Characteristics of Cow Skeleton

The pose of cows reflects their body condition, and the information contained in the skeleton can provide data support for lameness, estrus, milk yield, and contraction behavior detection. This paper presents an algorithm for automatically detecting the condition of cows in a real farm environment based on skeleton spatio-temporal features. The cow skeleton is obtained by matching Partial Confidence Maps (PCMs) and Partial Affinity Fields (PAFs). The effectiveness of skeleton extraction was validated by testing 780 images for three different poses (standing, walking, and lying). The results indicate that the Average Precision of Keypoints (APK) for the pelvis is highest in the standing and lying poses, achieving 89.52% and 90.13%, respectively. For walking, the highest APK for the legs was 88.52%, while the back APK was the lowest across all poses. To estimate the pose, a Multi-Scale Temporal Convolutional Network (MS-TCN) was constructed, and comparative experiments were conducted to compare different attention mechanisms and activation functions. Among the tested models, the CMS-TCN with Coord Attention and Gaussian Error Linear Unit (GELU) activation functions achieved precision, recall, and F1 scores of 94.71%, 86.99%, and 90.69%, respectively. This method demonstrates a relatively high detection rate, making it a valuable reference for animal pose estimation in precision livestock farming.

Vaginal and vestibular electrical resistance as an alternative marker for optimum timing of artificial insemination with liquid-stored and frozen-thawed spermatozoa in sows

Development of a pen-side test to objectively determine the ideal time for artificial insemination (AI) in the sow would save producers time and money. Current processes rely on identification of oestrus via subjective behavioural and physiological markers that are indicative of high blood oestrogen concentrations. This study attempted to use measurements of electrical resistance (ER) in the cervical mucus to pinpoint timing of AI accurately enough to lead to equivalent pregnancy rates as a natural mating. Thirty-six sows were divided into 3 groups and observed for signs of oestrus. Seven sows did not show any oestrus behaviour and were excluded from the study. The remaining 29 sows were inseminated via natural mating and conventional oestrus detection (n = 14), or inseminated artificially with either liquid-stored semen (n = 8) or frozen-thawed semen (n = 7) according to timing indicated from electrical resistance measurements in the vagina and vestibule. Sows that were artificially inseminated on the basis of the electrical resistance readings had a lower pregnancy rate (P = 0.034) and less piglets born alive per litter (P < 0.05) than those that were naturally mated according to a conventional oestrus detection regime. However, the pregnancy rate and total piglets born alive did not differ between the two groups that underwent artificial insemination. Change in electrical resistance in the vagina has the potential to accurately predict ovulation timing, but more work is required to refine the timing of AI in relation to the readings before the technique can be adopted by industry.

Intensity of estrus expression – valuable obvious determinant of fertility in Bos indicus cows

This study aimed to characterize estrus response and to establish relationships between intensity of estrus, preovulatory follicle (POF) size and estradiol (E2) concentrations on day of AI, luteal profiles and pregnancy outcome in lactating Hariana breed of cows. 200 cyclic cows were subjected to Ovsynch (n = 54) and Pre-OV treatment (n = 146). Ovsynch: Buserelin acetate (BA; 10 µg), Cloprostenol (500 µg) and BA (10 µg) were injected i.m. on day 0, 7 and 9, respectively, irrespective of treatment. Pre-OV: BA (10 µg) and Cloprostenol (500 µg) was also injected i.m. simultaneously 7 days prior to initiate Ovsynch. On the basis of estrus behavior, the cows were classified into three groups: weak, moderate and intense. Artificial insemination performed at 18–24 hours after 2nd BA of Ovsynch in both treatments. The average duration of estrus did not differ (p > 0.05) between Ovsynch and Pre-OV treatment. A positive correlation was observed between estrus response and POF size, concentration of E2 on day of AI and luteal profiles on day 12 post-AI. First service conception rate was higher in cows exhibited intense (45.46%) and moderate (42.56%) estrus response than weak (28.57%) estrus response. In conclusion, intensity of estrus expression could be considered as important determinant for deciding pregnancy outcomes in Bos indicus cows.

Effect of hCG administration on ovulation and estrus in Saanen goats subjected to short-term estrus synchronization protocol during the breeding season

This study aimed to compare the effect of hCG administered at 24 or 36 h following a short-term estrus synchronization treatment on the ovulation time and estrus parameters in non-lactating Saanen goats during the breeding season. The estrous cycles of does were synchronized with an intravaginal sponge containing 60 mg of medroxyprogesterone acetate (MAP) for six days, and an injection of 125 µg of d-cloprostenol at the time of sponge insertion in addition to an injection of 300 IU of eCG 24h before sponge removal. After removal of the sponges, does were injected intramuscularly either 1 ml physiological saline (0.9% NaCl) solution after 12 h (Group1/Control; n=10), 100 IU hCG after 24 h (Group2; n=9) or 100 IU hCG after 36 h (Group3; n=9). Estrus behavior after sponge removal was observed twice daily for 84 h using teaser bucks and transrectal ovarian ultrasonography was performed twice a day for seven days to determine small, medium and large follicle numbers, luteal development and the time of ovulation. Blood samples were collected on the same days to determine serum progesterone (P4) and estradiol (E2) concentrations. No significant differences were observed in terms of estrus parameters, ovarian structure and serum P4 and E2 concentrations between the hCG-treated groups and the control group. Average values observed for all groups: estrous response (53.57%), the interval from sponge removal to estrus and ovulation (35.2 h and 67.86 h, respectively), duration of estrus (18.4 h), the interval from estrus onset to ovulation (50.37 h), ovulation rate (96.43%), number of ovulations (1.36), ovulatory follicle diameter (6.86 mm), corpus luteum diameter (8.22 mm), follicle and luteal growth rate (1.17 and 0.68 mm/day, respectively). In conclusion, administration of hCG at 24 or 36 h following a short-term estrous synchronization protocol does not affect ovulation time, estrus parameters, and serum P4 and E2 concentrations in goats during the breeding season.

Abnormal mare behaviour is rarely associated with changes in hormonal markers of granulosa cell tumours: A retrospective study.

Abnormal or undesired mare behaviours are often assumed to be associated with ovarian abnormalities. We aimed to determine the incidence of abnormal behaviours and their association with concentrations of one or more ovarian hormones associated with a granulosa cell tumour (GCT). Retrospective descriptive. A total of 2914 hormonal profile samples submitted with the words behave, behaviour, or behaving in the submission history were analysed. The association between reported abnormal behaviours and concentrations of testosterone, anti-Müllerian hormone (AMH), inhibins and inhibin-B were assessed. Statistical analysis was performed using a Chi-squared test of association. Of the 2914 cases that were submitted due to behaviour issues, 2506 (86%) did not have any of the measured hormones reach GCT-like concentrations. The remaining 408 cases had either one (63%), two (25.5%), or three (11.5%) hormones with concentrations consistent with those from confirmed GCT cases. Testosterone had the lowest percent of GCT-like values among the cases (7.7%), compared with AMH (9.4%), inhibins (9.6%) and inhibin B (8.7%). Stallion-like behaviour was significantly associated with increased concentrations of all four hormones. In contrast, aggression, oestrous and other abnormal behaviours were significantly less likely to be associated with increased concentrations of the hormones. Retrospective study, using sample submission history. Overall, the abnormal behaviours among mares, except the stallion-like behaviour, were not associated with increased ovarian hormones. These results highlight the common misassumption about the involvement of the ovaries in 'abnormal behaviours' or 'undesirable behaviours' of mares.

Isoallopregnanolone Inhibits Estrus Cycle-Dependent Aggressive Behavior.

Among female rats, some individuals show estrus cycle-dependent irritability/aggressive behaviors, and these individual rats may be used as a model for premenstrual dysphoric disorder (PMDD). We wanted to investigate if these behaviors are related to the estrus cycle phase containing moderately increased levels of positive GABA-A receptor-modulating steroids (steroid-PAM), especially allopregnanolone (ALLO), and if the adverse behavior can be antagonized. The electrophysiology studies in this paper show that isoallopregnanolone (ISO) is a GABA-A-modulating steroid antagonist (GAMSA), meaning that ISO can antagonize the agonistic effects of positive GABA-A receptor-modulating steroids in both α1β2γ2L and α4β3δ GABA-A receptor subtypes. In this study, we also investigated whether ISO could antagonize the estrus cycle-dependent aggressive behaviors in female Wistar rats using a resident-intruder test. Our results confirmed previous reports of estrus cycle-dependent behaviors in that 42% of the tested rats showed higher levels of irritability/aggression at diestrus compared to those at estrus. Furthermore, we found that, during the treatment with ISO, the aggressive behavior at diestrus was alleviated to a level comparable to that of estrus. We noticed an 89% reduction in the increase in aggressive behavior at diestrus compared to that at estrus. Vehicle treatment in the same animals showed a minimal effect on the diestrus-related aggressive behavior. In conclusion, we showed that ISO can antagonize Steroid-PAM both in α1β2γ2L and α4β3δ GABA-A receptor subtypes and inhibit estrus cycle-dependent aggressive behavior.

Subcutaneous Administration of Melatonin Resumes the Cyclicity and Improves Conception Rate in Anestrus Buffalo Heifers

The present study was aimed to see the effect of subcutaneous injection of melatonin @ 18 mg/50 kg b.wt. on estrus induction and conception rate in anestrus buffalo heifers (n=24). Among the heifers treated with melatonin (n=14), 6 (42.86 %) animals showed behavioral estrus within 4-28 days of treatment as compared to none in control group (n=10). The first service conception rate was 33.33 % (2/6) in the melatonin treated buffaloes, while none of the buffalo exhibited estrus/conceived in control group. It is concluded that melatonin @ 18 mg/50 kg b.wt. can be used to induce the estrus in anestrus buffalo heifers with satisfactory conception rate.

Development and evaluation of an injectable slow-release progesterone formulation for estrus synchronization in ewes out of the breeding season.

This study was aimed at developing a type of slow-release progesterone micro-particles useable in a single intramuscular injection for estrus synchronization in non-breeding season ewes. A total of 66 ewes were randomly assigned into four groups: CIDR (n = 16): exposed to intravaginal CIDR for 12 days, and three experimental groups, i.e., T100 (n = 16), T150 (n = 17) and T200 (n = 17), receiving a single intramuscular injection of 100, 150 and 200 mg slow-release progesterone, respectively. Blood sampling was performed on all ewes at five different times, and the ELISA method measured progesterone levels. No significant differences were observed in progesterone levels among the groups in each sampling time. More than 90% of ewes in the CIDR, T100 and T150 groups and all those in T200 showed estrus behaviour, and the rate was not significantly different between groups. The difference in the mean interval from progesterone treatment to estrus was also insignificant. The parturition rate declined by increasing the dose of injected progesterone; although it was similar in CIDR and T100 groups, it decreased significantly in T150 and T200 . Since our injectable progesterone formulation was successful in the induction and synchronization of estrus in ewes out of the breeding season, it can be applied as an alternative to the conventional progesterone containing intravaginal devices.

165 Randel Lecture: Androgen Excess Domestic Livestock Models—What can they Tell us About the Mechanisms Underlying Anovulation?

Abstract Ovulatory disorders are a major factor in female infertility. Our laboratory has identified several populations of cows and a population of sheep that have excess androgen (High A4) in dominant follicles and ovarian cortex cultures in the US and in the Middle East with increased steroidogenic enzyme production in somatic cells. Within our research herd, the High A4 females have irregular estrous cycles where behavioral estrus and ovulation are not coupled and are often anovulatory. Follicular waves of growth, during the estrous cycle, are disrupted in High A4 cows with development of persistent follicles, and an absence of normal follicular-wave estrogen patterns in blood plasma compared with Controls. Increased ovarian cortex fibrosis, oxidative stress markers and plasma pro- inflammatory lipids were present in High A4 cows indicating increased inflammation. High A4 granulosa cells have altered gene transcripts indicating cell cycle arrest and expression of genes enriched in other somatic cell types resulting in altered cell identity. Furthermore, High A4 ovarian cortex cultures secrete increased pro-inflammatory cytokines and have reduced follicle progression to later stages supporting follicular arrest. Treatment of High A4 ovarian cortex cultures with Vascular Endothelial Growth Factor 165 suppressed excess steroids, fibrosis, pro-inflammatory cytokines and relieved follicular arrest. Concentrations of Anti-Mullerian Hormone (AMH) were greater in High A4 vs Controls in both follicular fluid and ovarian cortex culture media supporting that AMH could be a factor contributing to follicular arrest. Many of the characteristics of High A4 cows and sheep identified are similar to polycystic ovary syndrome (PCOS) in women. Thus, High A4 cow and sheep are excellent models to unravel androgen excess molecular mechanisms involved in follicular arrest and female infertility contributing to anovulation.

Impaired luteal progesterone synthesis observed in gilts with PMSG/hCG-induced estrus affects the expression of steroid, prostaglandin, and cytokine receptors in the endometrium and myometrium during the peri-implantation period

Abstract The present study aimed to examine the effect of impaired progesterone (P4) synthesis, observed in gilts with gonadotropin-induced estrus, on the uterine expression of receptors important for pregnancy establishment. Twenty prepubertal gilts received 750 IU PMSG and 500 IU hCG 72 h later, while 18 prepubertal gilts in the control group were observed daily for estrus behavior. Gilts were inseminated in their first estrus and slaughtered on days 10, 12, and 15 of pregnancy to collect endometrial and myometrial tissues for mRNA analysis using real-time PCR. As we previously described, gilts with PMSG/hCG-induced estrus showed decreased luteal P4 synthesis on days 10 and 12 of pregnancy. PMSG/hCG treatment did not affect P4 receptor mRNA expression in either uterine tissue. In the endometrium, a greater mRNA transcript abundance of estrogen receptors (ESR1 and ESR2), androgen receptor (AR), prostaglandin (PG) E2 receptors (PTGER2 and PTGER4), PGF2α receptor (PTGFR), interleukin 6 receptor (IL6R), and tumor necrosis factor α receptors (TNFRSF1A and TNFRSF1B) was detected in gilts with natural than with PMSG/hCG-induced estrus (P&lt;0.05). In the myometrium, the mRNA expression of AR, PTGER2, and PTGFR was lower, while PGI2 receptor (PTGIR) transcript abundance was elevated in the gilts treated with PMSG/hCG as compared with the control animals (P&lt;0.05). In summary, a decreased luteal P4 level during the peri-implantation period in gonadotropin-stimulated pigs affects endometrial and myometrial receptor expression, with the endometrium being more sensitive to impaired P4 synthesis. Whether the observed changes alter uterine receptivity to local and systemic factors remains to be elucidated.

The Effect of Treatment with Oestradiol Benzoate on Oestrus Expression and Endometrial Oedema in Anovulatory and Cyclic Mares.

Oestrogens treatment is often used to induce oestrus behaviour in anoestrous mares to aid in the collection of stallion semen and as recipient mares to receive embryos when combined with progesterone. However, there are no studies to describe the effect of dose and individual mare on the intensity and duration of the response, in both anoestrous and cyclic mares. In Experiment 1, 13 anoestrous mares were treated with one of five doses of oestradiol benzoate (OB) (1, 1.5, 2, 3 and 4 mg) per mare in five consecutive treatment periods (n = 65), to determine the response in terms of endometrial oedema and oestrous behaviour. Experiment 2 and 3 used 3 mg of OB in cyclic mares to confirm or deny the presence of an active corpus luteum (CL). There was a dose rate of OB and individual mare effect (p < 0.05) on the intensity and persistence of endometrial oedema and oestrous behaviour. A total of 2 mg OB was enough to induce endometrial oedema and oestrous behaviour within 48 h in most mares. Mares with an active CL did not show endometrial oedema following treatment of 3 mg OB.

A Recognition Method of Ewe Estrus Crawling Behavior Based on Multi-Target Detection Layer Neural Network.

There are some problems with estrus detection in ewes in large-scale meat sheep farming: mainly, the manual detection method is labor-intensive and the contact sensor detection method causes stress reactions in ewes. To solve the abovementioned problems, we proposed a multi-objective detection layer neural network-based method for ewe estrus crawling behavior recognition. The approach we proposed has four main parts. Firstly, to address the problem of mismatch between our constructed ewe estrus dataset and the YOLO v3 anchor box size, we propose to obtain a new anchor box size by clustering the ewe estrus dataset using the K-means++ algorithm. Secondly, to address the problem of low model recognition precision caused by small imaging of distant ewes in the dataset, we added a 104 × 104 target detection layer, making the total target detection layer reach four layers, strengthening the model's ability to learn shallow information and improving the model's ability to detect small targets. Then, we added residual units to the residual structure of the model, so that the deep feature information of the model is not easily lost and further fused with the shallow feature information to speed up the training of the model. Finally, we maintain the aspect ratio of the images in the data-loading module of the model to reduce the distortion of the image information and increase the precision of the model. The experimental results show that our proposed model has 98.56% recognition precision, while recall was 98.04%, F1 value was 98%, mAP was 99.78%, FPS was 41 f/s, and model size was 276 M, which can meet the accurate and real-time recognition of ewe estrus behavior in large-scale meat sheep farming.