P4 Concentrations Research Articles

Diagnosing american bison pregnancy during its two last trimesters: Comparison between rectal palpation associated with ultrasonography and hormonal assays in serum or in feces

The study aimed to propose sensitive, specific and easy pregnancy diagnosis for American Bison. Trans-rectal Palpation and Ultrasonography (TRPUS), concentration of Pregnancy Associated Glycoproteins (PAG), Progesterone (P4), Estrone (E1), Estrone-Sulfate (E1S) in serum and P4 and E1S in feces were compared. Immunoassay was used for PAG, whereas steroids were assayed using Liquid Chromatography coupled to Mass Spectrometry. Pregnancy and its period were retrospectively assessed after calving. Animals included were distributed as follows: 40 were non-pregnant, 27 were in their second and 15 in their third trimester of gestation. Fisher’s test was used to determine sensitivity and specificity of TRPUS. Thresholds leading to best sensitivities and specificities for hormonal assays were determined using Receiver Operating Characteristic Curves. Although TRPUS requires contention, palpation skills, it was conclusive in 70.63 % of cases and good sensitivity (97.50 %) and decent specificity (83.33 %) were observed. Concentrations of PAG, P4, E1S and E1 in serum were higher in Pregnant animals (P), with thresholds giving decent specificity and sensitivity (lower sensitivity for E1 and E1S: 92.11 %; lower specificity for P4: 93.48 %). In feces, P4 and E1S were higher in P: pregnancy diagnosis using E1S assay in feces showed 100 % of sensitivity and specificity. In conclusion, assaying E1S in feces during the two last trimesters of American Bisons pregnancy is a sensitive and specific gestation diagnosis. Pregnancy diagnosis using TRPUS can be useful in ranches but requires contention and skill adaptation. Serum hormonal assays can help evaluating the pregnancy period but also require contention.

Impact of the estrous cycle on brain monoamines and behavioral and respiratory responses to CO2 in mice.

The prevalence of panic disorder is two to four times higher in women compared to that in men, and hormonal changes during the menstrual cycle play a role in the occurrence of panic attacks. Here, we investigated the effect of the estrous cycle on the ventilatory and behavioral responses to CO2 in mice. Female mice in proestrus, estrus, metestrus, or diestrus were exposed to 20% CO2, and their escape behaviors, brain monoamines, and plasma levels of 17β-estradiol (E2) and progesterone (P4) were measured. Pulmonary ventilation (V̇E), oxygen consumption (V̇O2), and body core temperature (TB) were also measured during normocapnia followed by CO2. Females exposed to 20% CO2 exhibited an escape behavior, but the estrous cycle did not affect this response. Females in all phases of the estrous cycle showed higher V̇E and lower TB during hypercapnia. In diestrus, there was an attenuation of CO2-induced hyperventilation with no change in V̇O2, whereas in estrus, this response was accompanied by a reduction in V̇O2. Hypercapnia also increased the concentration of plasma P4 and central DOPAC, the main dopamine metabolite, in all females. There was an estrous cycle effect on brainstem serotonin, with females in estrus showing a higher concentration than females in the metestrus and diestrus phases. Therefore, our data suggest that hypercapnia induces panic-related behaviors and ventilatory changes that lead to an increase in P4 secretion in female mice, likely originating from the adrenals. The estrous cycle does not affect the behavioral response but interferes in the ventilatory and metabolic responses to CO2 in mice.

Effect of the Lactation Phases on the Amplitude of Variation in Blood Serum Steroid Hormones and Some Hematochemical Analytes in Three Dairy Cow Breeds.

Lactation in dairy cows implies comprehensive endocrine and metabolic changes including a systemic electrolytic reaction. Previous studies have rarely considered these specific demands due to the influence of lactation periods. Therefore, this study aimed to assess the effects of early, middle, and late lactation phases on the dynamic changes in serum concentrations of progesterone (P4), 17β-oestradiol (E2), cortisol, and some electrolytes (Ca++, Mg++, Na+, K+, Cl-, Pi) and biochemical parameters (alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK), total bilirubin, urea, and iron (Fe++) in 10 Holstein, 10 Brown Swiss, and 10 Modicana multiparous healthy dairy cows (4.2 ± 1.7 years of age) sampled at 60-day intervals throughout lactation. Lactation induced significant changes in the concentrations of P4, which peaked at >120-180 days, decreased at >240-300 days, and increased again after 300 days. Cortisol showed an opposite trend to P4, with concentrations progressively decreasing, except for the phase between >240 and 300 days, and a steep drop at >300 days compared to previous phases. Na+ concentrations showed the lowest values at 0-60 d and the highest ones at >180-240 days, whereas Mg++ showed the highest values at >60-120 d and the lowest at >300 d. Significant correlations were found between P4 with cortisol, Cl- and K+, and cortisol with Ca++ and LDH. Significant differences in average concentrations of AST, ALT, LDH, Ca++, Mg++, and Fe++ were observed among different dairy cow breeds. Understanding the dynamic changes in hormone levels, electrolytes, and biochemical parameters during different lactation phases, while considering breed differences in dairy cows, is crucial for improving herd health management and milk production in commercial dairy farms.

Effects of cloprostenol and oxytocin on ultrasonographic changes of uterine horns in postpartum primiparous Hu sheep

This study aimed to evaluate the effects of exogenous hormones on postpartum ultrasonographic changes of uterine horn in Hu sheep. 90 nulliparous Hu sheep were divided into three groups according to the number of lambs. Each group was further randomly subdivided into three groups (n = 10), a control group (sodium chloride), a PG group (cloprostol), and a PG+OT group (cloprostol + oxytocin). The effects of different treatments on ultrasonographic changes of uterine horn and reproductive performance of ewes were determined after the treatment. Then, 90 nulliparous ewes were divided into a control group, PG group, and PG+OT group according to hormone injections received. Each group (n = 30) consisted of 10 single, 10 twin, and 10 triple ewes. Changes in the levels of hormones P4, LH, FSH, and E2 in the serum of postpartum ewes, the time of the first estrus, and the conception rate were detected. Results showed that the higher the lambing rate, the slower the rate of ultrasonographic changes of uterine horn. The rate of ultrasonographic changes of uterine horn in the PG+OT group was faster than that in respective PG and the control groups. Caruncle diameter was not affected by the number of lambs or hormone treatment. After delivery, the concentrations of P4 and LH increased rapidly and remained at a relatively high level, while the concentration of E2 increased in all ewes. The PG+OT group had lower P4 concentrations compared to the control group, but higher LH, FSH, and E2 levels. The time to first postpartum estrus was significantly shorter in the PG+OT group, but differences in pregnancy rate were not significant. Thus, PG+OT treatment can significantly accelerate postpartum ultrasonographic changes of uterine horn, which can prepare postpartum ewes for the next reproductive cycle.

Evaluation of Four Different Automated Activity Monitoring Systems to Identify Anovulatory Cows in Early Lactation.

The objective of this study was to evaluate four different automated activity monitoring (AAM) systems to identify anovulatory cows in early lactation. A total of 852 lactating Holstein cows (221 primiparous and 631 multiparous cows) from four commercial dairy herds were enrolled. On each farm, cows were equipped with a respective AAM system (SB: Smartbow; HT: Heatime; DP: Delpro; and CM: CowManager). Each cow was sampled three times within the voluntary waiting period (VWP) in a two-week interval to detect the blood progesterone (P4) concentration. Cows were classified based on the concentration of P4 as follows: (1) none of the three blood P4 concentrations exceeded 1.0 ng/mL (anovulatory); (2) at least one of the three blood P4 concentrations was above 1.0 ng/mL (ovulatory). Cows were classified based on estrus alerts as follows: (1) no estrus alert was detected by an AAM system from 7 to 60 DIM (anestrus); (2) at least one estrus alert was detected by an AAM system from 7 to 60 DIM (estrus). Accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were calculated for each AAM system for anovulatory cows [(SB: 77.6%; 26.8%; 89.3%; 36.7%; and 84.1%); (HT: 79.2%; 63.6%; 83.6%; 52.8%; and 88.9%); (DP: 47.2%; 78.8%; 41.5%; 19.5%; and 91.6%); (CM: 80.5%; 23.7%; 92.7%; 39.1%; and 85.3%)].

The impact of enhanced early postnatal nutrition on the histomorphological features of the ovaries in fat-tailed Sanjabi ewe lambs.

This study aimed to investigate whether providing additional ad libitum feeding could improve reproductive characteristics in prepubertal ewe lambs. Twelve Sanjabi ewe lambs, approximately one-month-old and with an average initial weight of 11.6 ± 1.3kg, were monitored over a 3-month period, which was divided into three distinct periods of 30 days each. The first period spanned from the lambs' age of one to two months, the second period covered their age range of two to three months, and the third period encompassed their age range of three to four months. The lambs were randomly assigned to either a control group (C) or a treatment group (T). The control group received a basal diet consisting of hay and milk, whereas the treatment group received an enhanced diet comprising hay, milk, and concentrate. Live weight (LW) and average daily gain (ADG) were measured weekly, and blood samples were collected from the jugular vein at days 30, 60, and 90 of the experiment to determine the concentrations of progesterone (P4) and estrogen (E2). Following the 90-day experiment, the lambs were humanely euthanized in accordance with established protocols. Subsequently, both ovaries from each animal were removed, weighed and subjected to a comprehensive histological analysis. The ovaries underwent fixation, embedding, and sectioning procedures, followed by staining with hematoxylin and eosin (H&E) to facilitate microscopic examination. Ovary microscopic sections from both C and T groups were examined to assess follicles at various developmental stages, including primordial follicle number (PreFN) and diameter (PriFD), primary follicle number (PriFN) and diameter (PriFD), secondary follicle number (SFN) and diameter (SFD), antral follicle number (AFN) and diameter (AFD), and granulosa layer thickness of secondary (GLTSF) and antral follicles (GLTAF). The impact of diet and three experimental periods on ADG and LW exhibited significant variations. There was a significant increase (P < 0.05) in LW in the T group compared to the T group, with noticeable differences in LW fluctuations observed during distinct periods. However, ADG was more prominent in the initial and second observation periods than in the third. The impact of diet and experimental periods on P4 and E2 concentrations was found to be negligible. The T group showed significant improvements (P < 0.05) in PreFD, PriFN, and GLTAF compared to the C group. This study suggests that ad libitum concentrate feeding may promote reproductive characteristics in prepubertal ewe lambs. Further research is needed to explore its potential impact on the age of puberty.

Effect of gonadorelin dose and an additional gonadorelin treatment 2 d after the initiation of Resynch-25 on ovarian dynamics and fertility of lactating Holstein cows

Our objective was to improve ovulatory response at the initiation of the Resynch-25 protocol by (1) increasing the dose of GnRH from 100 µg to 200 µg; and (2) giving a second GnRH treatment 56 h after the initiation of the protocol. We considered the experimental d 0 the day of the previous service. The experiment consisted of a 2 × 2 factorial design to compare the main effects of GnRH dose (100 vs. 200 µg) and GnRH treatment times (once vs. twice 56 h apart). A total of 2,111 previous services in 1,438 Holstein lactating cows were used. On d25, cows were assigned to receive either 100 or 200 µg of GnRH only on d25 or on d25 and 56 h later (d27). On d 32, cows diagnosed as nonpregnant (n = 1,076 services) were classified as with or without a corpus luteum (CL). Nonpregnant cows with a CL continued the Resynch-25 protocol receiving PGF2α treatments on d 32 and 33, followed by a GnRH 32 h later and timed AI 16 h after the last GnRH. Blood samples were collected in a subset of cows on d 25, 32, and 34 to assess serum P4 concentrations. In the same subset of cows, transrectal ultrasonographic examinations were performed on d 25, 29, 34 and 36 to assess ovarian parameters and ovulatory response to the GnRH treatments. The overall ovulatory response at the initiation of the protocol, defined as the ovulation between d 25 and 29, was not affected by days of GnRH treatment and averaged 41.9%. On the other hand, nonpregnant cows treated with the higher GnRH dose had a greater ovulatory response at the initiation of the protocol compared with cows treated with the lower dose (48.0% vs. 36.1%). Despite the increase in ovulatory response at the initiation of the protocol, the GnRH dose did not affect fertility of cows submitted to Resynch-25. Furthermore, the second GnRH treatment on d27 tended to decrease pregnancy per AI on d32 after AI (39.0% vs. 43.9%), but no effect of days of GnRH treatment was observed in the subsequent pregnancy diagnosis. The absence of a functional CL on d25 and ovulation at the initiation of the protocol were positively associated with improved fertility. However, the improvement in fertility of cows ovulating at the initiation of the protocol occurred only in cows with a functional CL on d25. In summary, despite increasing ovulatory response at the initiation of the protocol, the higher dose did not improve fertility. The extra GnRH on d27 did not increase ovulatory response at the initiation of the protocol and tended to decrease P/AI 32 d after AI of the Resynch-25. Also, no additive effect of the higher dose and extra GnRH treatment was observed. Despite the lack of overall treatment effect, data presented in this study suggests that the identification of CL functionality on d25 may help to optimize the resynchronization strategy used at nonpregnancy diagnosis to potentially increase fertility of cows reinseminated.

Effects of exogenous progesterone on the ovine serum progesterone profile during the non-breeding season

Exogenous progesterone (PRG) sources are used to induce ovine estrus during the non-breeding season. Intramuscular injection (IM) of PRG is an uncommon route for this purpose. This study investigated serum progesterone (P4) levels after IM administration of 50 mg of two different PRG products. Ten ewes were selected and received two consecutive PGF2α injections at 24-h intervals. Serum samples were collected (Time 0), followed by the injection of single doses of Fertigest® or Vetagesterone®. Serum P4 levels were assayed at times (T) 0, 30 min, 3,6,12,24,48,72,96, and 120 h after injection. A large variation in the serum P4 levels at T0 was detected. The serum P4 level at T0 was 4.3 ng/mL, which is considerable for anestrus ewes, following PGF2α administration. The mean time to reach maximum serum P4 concentration was 5.8 h, with a mean concentration of 22.5 ng/mL. Serum P4 levels returned to basal values (T0) after 48 h. An increased P4 production rate (PR) was detected following PRG administration, which continued for 24 h. A single injection of PRG reduced the variety of serum P4 levels from 24 h onward. The two different PRG generated different serum P4 concentrations. This study indicates an unusual change in serum P4 levels in anestrus ewes following PGF2α administration. 48 h after 50 mg PRG injection, the plasma levels of P4 reached basal levels in anestrus ewes.

The efficiency of injectable P4 combined with the male effect on the pregnancy rate of boer goats in the off-season

Goats are seasonally polyestrous, which implies that the kid production is restricted to once a year. However, through estrous cycle manipulation, the production can be distributed throughout the year. Therefore, the present study aimed to estimate the reproductive viability of Boer female goats after administration of injectable P4, either combined with the male effect or independently, during the off-season in the southern region of Paraná. The outcomes evaluated in the study included the pregnancy rate, parturition rate, twin births, number of births, and concentration of births. The study was conducted in a beef goat farm, using 72 goats randomly assigned to three experimental groups. In the G1 group (n=22), females were stimulated by the male effect, in the G2 group (n=25), the animals received 75 mg of P4 intramuscularly at the beginning of the experiment, and in the G3 group (n=25), the goats received 75 mg of P4 intramuscularly at the beginning of the experiment combined with the male effect. The goats were in a breeding season of 60 days. The pregnancy rate, parturition rate, percentage of twin births, and the number of kids born per group were evaluated. The use of injectable P4 showed a similar pregnancy rate to the other groups, with a higher concentration of births in the G1 and G3 groups, both of which were subjected to the male effect (p&lt;0.05). Furthermore, more studies should be carried out using different P4 concentrations.

EFFECT OF LUTEAL REGRESSION ON CONCEPTION RATES IN POSTPARTUM ANESTRUS MURRAH BUFFALOES USING G48 AND G56 OVSYNCH PROTOCOLS

The present study aimed to investigate the effect of luteal regression on the conception rates in postpartum anestrus graded Murrah buffaloes. Ovsynch protocols: G48 group (n=10) and G56 (n=10) graded Murrah buffaloes, both received a 20 µg dose of GnRH on day 0, followed by 500 µg of PGF2α on day 7. On day 9, a final dose of 20 µg of GnRH was administered 48 hours after PGF2α for G48 and 56 hours after for G56. Fixed-time artificial insemination (FTAI) was conducted at 16-21 hours after 2nd injection in both groups. The luteal regression rates in both the groups were evaluated by progesterone hormone (P4) assay at different days of treatment. The results showed that in both groups, the concentration of P4 differed significantly (P&lt;0.05) between and within groups at different days of treatment. In conclusion, it was found that the G56 group (70.00 per cent) had a higher overall conception rate than the G48 group (50.00 per cent) due to better luteal regression.

Effect of post-mating administration of ketoprofen on serum progesterone concentration and fertility in Akkaraman ewes.

A major cause of early embryonic losses is inadequate secretion of progesterone (P4) hormone due to luteal insufficiency in farm animals. Post-mating applications that directly or indirectly increasing serum P4 concentrations have a positive effect on fertility. The aim of this study was to investigate the effect of post-mating administration of ketoprofen on serum P4 concentration and fertility in Akkaraman ewes synchronized with a short-term protocol during the breeding season. Oestrus monitoring ewes after synchronization were hand-mated and randomly assigned to two equal groups (Ketoprofen vs. Control). Ewes in the ketoprofen group (KPG) (n = 40) were administered with ketoprofen (Rifen, Richter pharma, Austria) intramuscularly (im) at a dose of 3mg/kg on days 9 and 10 after mating. In the control group (CG) ewes (n = 40) were administered with saline im on the same days. Blood samples were collected from ewes in both groups at four different time points of post-mating days (9, 12, 15 and 18 days). The results showed that there were no statistical differences between the KPG and CG groups on fertility parameters; pregnancy rates (85% vs. 72.5%), lambing rates (100% vs. 100%), single birth rates (55.9% vs. 55.2%), multiple birth rates (44.1% vs. 44.8%), litter sizes (1.56 vs. 1.55). In pregnant ewes, serum P4 concentrations on day 18 (4.35 ± 0.34 ng/mL) in the KPG group were higher than (3.27 ± 0.27 ng/mL) in CG group (P < 0.05). It was concluded that post-mating ketoprofen administration have no significant effect on fertility, but significantly increased the serum P4 concentration on day 18 in pregnant ewes.

PSIV-29 Efficacy of a chute-side pregnancy test on early pregnancy determination in mature Rambouillet ewes

Abstract Distinguishing pregnant from non-pregnant ewes in early pregnancy allows for more efficient flock management by producers. While early pregnancy detection techniques like ultrasonography and hormone quantification are well established, these techniques are often not adaptable to field conditions or require specialized equipment and training. The objective of this study was to evaluate a validated bovine commercial on-farm pregnancy test on efficacy for detecting early pregnancy in distinct blood constituents of ewes. Rambouillet ewes [n = 30; average body weight (BW) = avg 60.9 ± 1.1 kg; age 2 to 8 yr) were estrous synchronized using a 5 d CIDR protocol followed by 2 injections of PGF2α at 0 and 4 h. A rattle-painted ram was subsequently placed with ewes for a 35-d breeding season. Blood constituents including whole blood (WB), plasma (PL), and serum (SE) were collected via jugular venipuncture prior to synchronization (d 0) and on d 20, 35, and 70 after breeding. Blood constituents were individually evaluated using the IDEXX Alertys OnFarm pregnancy test for pregnancy detection. Trans-abdominal ultrasonography was performed on d 35 and d 70 post-breeding. Serum progesterone (P4) was quantified on d 100 of gestation to confirm pregnancy status. Progesterone concentrations ≥ 4 ng/mL were considered pregnant. On d 20 of gestation, IDEXX tests agreed with P4 concentrations on d 100 (χ2 = 0.30) in WB, SE and PL at 35.7, 53.6, and 53.6%, respectively. Pregnancy detection accuracy increased on d 35 of gestation as IDEXX tests agreed with P4 at d 100 (χ2 = 1.00) in WB, SE, and PL at 60.7, 60.7 and 60.7% accuracy, respectively. On d 70 of gestation, IDEXX tests agreed with P4 at d 100 (χ2 = 0.81) in WB, SE, and PL at 90.7, 93.3 and 93.3% accuracy, respectively indicating similarity in pregnancy diagnosis in the two methods. Detection of pregnancy using ultrasonography at d 35 identified 33% of pregnant ewes, while d 70 ultrasound detected 93% of pregnant ewes when compared with d 100 serum P4. Results suggest that the IDEXX pregnancy test provides early diagnosis of pregnancy with d 70 results comparable to d 100 serum P4 quantification regardless of blood constituent type.

Reproductive outcomes of prepubertal Bos indicus beef heifers raised in a pasture-based feeding system submitted to ovulation induction strategies prior to a timed-artificial insemination protocol

Reproductive outcomes were evaluated in Nelore (Bos indicus) heifers submitted to one, two or no ovulation induction protocols based on progesterone (P4) and estradiol (E2) prior to a timed-artificial insemination (TAI) protocol. A total of 1,437 heifers (13.0 ± 0.8 mo old; 3.1 ± 0.1 of body condition score [BCS] and 279.9 ± 25.8 kg of body weight [BW]) were randomly assigned to 1 of 3 treatments: 0IND (n = 486): no ovulation induction protocol; 1IND (n = 481): one ovulation induction protocol; or 2IND (n = 470): two ovulation induction protocols. On Day −47, heifers from 2IND received a disinfected intravaginal P4 device (2 g, previously used for 21 d), kept until Day −40, when 0.5 mg of E2 cypionate (EC) was given. On Day −19, heifers from 2IND and 1IND underwent the same protocol. On Day 0, all heifers were submitted to the same TAI protocol, starting with a P4 device (0.5 g), 0.5 mg of cloprostenol sodium (PGF), and 1.5 mg of E2 benzoate. On Day 7, P4 device was removed, 0.5 mg of PGF, 0.5 mg of EC, and 200 IU of equine chorionic gonadotropin (eCG) were administered. The TAI was performed 2 d later (Day 9). Blood samples were collected on Days −47 and 0, to determine the presence of CL (circulating P4 concentrations ≥ 1.0 ng/mL). Ultrasound was performed on Days 40, 75 and between Day 150 and parturition to assess pregnancy per AI (P/AI) and pregnancy loss (PL). Statistical analyses were performed using SAS 9.4 (a-cP ≤ 0.05; A,B0.05 < P ≤ 0.10). The proportion of heifers with CL on Day −47 was similar among groups (3.4%). A greater proportion of heifers from 1IND had CL on Day 0, followed by 2IND, then 0IND (87.9a; 80.4b; 28.8c%). There was an effect of treatment on expression of estrus (2IND: 66.6a; 1IND: 67.2a; 0IND: 57.4b%), P/AI on Day 40 (2IND: 53.4a; 1IND: 43.9b; 0IND: 46.5b%), P/AI on Day 75 (2IND: 49.8a; 1IND: 40.5b; 0IND: 44.4ab%) and final P/AI (2IND: 45.5a; 1IND: 35.8b; 0IND: 40.5ab%). No differences were observed in PL (40–75 = 6.3%; 75-final = 9.6%; Total = 15.3%). Particularly within lighter heifers, there was an effect of treatment on P/AI on Day 40 (0IND: 39.2b; 1IND: 43.3ab; 2IND: 53.9a%) and on Day 75 (0IND: 36.6B; 1IND: 39.0AB; 2IND: 48.5A%). At the first pregnancy diagnosis, more nonpregnant heifers from 2IND had CL on Day 40 than 0IND, but 1IND did not differ from the other groups (85.4a; 74.8b; 80.8ab%). In conclusion, ovulation induction protocols performed prior to the TAI protocol increased the proportion of heifers with CL on Day 0. The use of two induction protocols resulted in greater fertility, particularly in lighter heifers, and increased cyclicity among nonpregnant heifers. These results indicate that this strategy may be an optimized method for inducing cyclicity and enhancing fertility of prepubertal Nelore heifers raised in pasture-based feeding systems.

SERUM DYNAMICS OF SOME REPRODUCTIVE HORMONES IN POSTPARTUM ANOESTRUS FRIESIAN X BUNAJI COWS TREATED WITH TWO DOSAGE REGIMENS OF OVSYNCH PROTOCOL

Fertility of the Post-partum period in dairy cattle is negatively influenced by the incidence of anoestrus. This condition is characterized by the absence of eostrus behaviour which may be due tophysiologic or pathologic factors. This study therefore, was aimed to compare the serum profiles of follicle stimulating hormorne (FSH), luteinising hormone (LH) and progesterone (P4) in response to the administration of two doses of gonadotrophin releasing hormone (GnRH, Lecirelin®) in combination with prostaglandin F2 alpha (PGF2α, Synchromate®) ovsynch protocol in apparently healthy, post-partum anestrous Friesian x Bunaji cows. Fifteen (n=15) animals were randomly divided into three groups and treated as follows: Group I (n=5) animals (control); Group II (n=5) animals received ovsynch 50 µg GnRH treatment; Group III (n=5) animals received 100 µg GnRH ovsynch treatment. Blood samples were collected at 15 to 30 minutes intervals for 6 hours to determine serum concentration of FSH and LH and once daily for 12 days after the injection of the first GnRH to determinate the concentration of plasma P4 using Enzyme linked immunosorbent assay kits. Peak values of FSH and LH were significantly (p&lt;0.05) different on days 0 and 9.The plasma P4 levels increased among treated cows following injection of GnRH reaching a peak on day 7 compared to the control group. It was therefore concluded that the ovsynch protocol at the dosages indicated enhanced FSH, LH and P4 profiles compared to control cows and could initiate the onset of ovarian activity in the post-partum anoestrus Friesian x Bunaji cows.

Adjusting the timing of inseminations to the time lag on luteolysis alerts results in higher conception in dairy cattle

Dairy cow fertility is a complex trait that depends on the cow's physiological status, the farm's environmental and management conditions, and their interactions. Already the slightest improvement in fertility can positively impact a farm's profitability and sustainability. In research, milk progesterone (P4) has often been used as an accurate and feasible way to identify a dairy cow's reproduction status. Moreover, in Europe and Canada, it has been used to improve fertility management on commercial farms as it allows to accurately identify reproduction issues, pregnancy and the optimal insemination window. An on-farm P4 device (OPD) automatically samples, measures and monitors the milk P4 concentration of individual cows. To this end, the P4 data is smoothed to be robust for measurement errors and outliers, and fixed thresholds are used to estimate the time of luteolysis preceding ovulation, thereby generating a luteolysis alert (LA). By smoothing the P4 data, the OPD introduces a time lag on the LA. Variation in this time lag is not considered in the estimation of the optimal insemination window that is advised to the farmer. Ignoring this variation might decrease the accuracy of the optimal insemination window and, therefore, decreases the likelihood of conception. We hypothesize that considering the length of the time lag and adapting the advice accordingly improves the conception rate. This observational retrospective study uses an extensive data set from 17 commercial dairy farms that are equipped with an OPD. We estimated the time lag on the alerts and evaluated their relationship with the interval from LA to insemination for successful (n = 3721) and unsuccessful inseminations (n = 3896) separately. Results showed that the probability of conception increases when a longer LA time lag is compensated with a shorter interval from LA to insemination and vice versa. In addition, for successful inseminations, we found a clear negative relation between the time lag and the interval from LA to insemination and the interval was significantly shorter when the time lag of the LA was longer. This negative relation between time lag and interval from LA to insemination was less pronounced for unsuccessful inseminations. Additionally, we evaluated the conception rates for inseminations that are performed too early, in time or too late with respect to the optimal insemination window advised by the OPD, in function of their associated time lags. We found that, for inseminations that were preceded by a short time lag (<8 h), the conception rate was 17.5 percentage points higher when cows were inseminated later than advised. Likewise, when inseminations were preceded by a long time lag (≥24 h), we found that the conception rate was 13 percentage points higher when cows were inseminated earlier than advised. Our results suggest that farmers using an OPD could potentially increase their conception success by compensating the variable time lag on the LA by adapting the interval from alert to insemination accordingly. This could be used to develop reproductive management strategies to improve reproductive performance on those farms, which can positively impact their sustainability.

Corpus luteum proximity alters molecular signature of the small extracellular vesicles and cumulus cells in the bovine ovarian follicle environment

Progesterone (P4) is predicted to act as a negative regulatory hormone for oocyte maturation events; however, its local effects during follicular development remain poorly understood in bovine. The complex process of oocyte meiosis progression is dependent on cellular communication among follicular cells. Besides, the breakdown of this communication, mainly between cumulus cells (CC) and oocyte, through the retraction of cumulus projections connecting these cells can impact oocyte maturation. In our study, we observed that follicles from the ovary ipsilateral to the corpus luteum (CL) containing high intrafollicular P4 concentrations enhance the abundance of proteins detected in follicular-derived small extracellular vesicles (sEVs) predicted to be involved in the retraction of membrane projections based on actin filaments, such as transzonal projections (TZPs). Conversely, we found that follicles from the ovary contralateral to the CL, which contained low intrafollicular P4 concentrations, had a high detection of proteins predicted to regulate the maintenance of TZPs. We also performed RNAseq analysis which demonstrated that 177 genes were differentially expressed in CC under the different P4 environments. Bioinformatic analysis points to changes associated to cell metabolism in cells from follicles ipsilateral to the CL in comparison to genes involved in cell communication in CC from follicles contralateral to the CL. Our functional analysis experiment confirmed that supplementation of cumulus-oocyte complexes during in vitro maturation with P4 at concentration similar to ipsilateral follicles reduces the number of TZPs. In summary, our study underscores a direct association between P4 concentration and cumulus-oocyte interaction, with potential consequences for the acquisition of oocyte competence.

Histological Characteristics of Follicles, Reproductive Hormones and Transcriptomic Analysis of White King Pigeon Illuminated with Red Light.

Red light (RL) has been observed to enhance egg production in pigeons, yet the underlying histological characteristics and molecular mechanisms remain less understood. This study included fifty-four pigeons to assess follicular histology, reproductive hormones, and ovarian transcriptomics on the third day of the laying interval under RL and white light (WL). The results showed that the granulosa cell layer was significantly thicker under RL (p < 0.05), whereas the theca cell and connective tissue layers showed no significant differences (p > 0.05). Higher plasma estradiol (E2) levels were recorded in the RL group (p < 0.05), as well as follicle stimulating hormone (FSH), although progesterone (P4) levels were higher under WL (p < 0.05). Moreover, P4 concentrations in follicle yolk significantly decreased under RL (p < 0.01), with higher FSH and E2 levels in F1 yolk and similar increases in SF1 yolk (p < 0.01). Transcriptomic analysis revealed 4991 differentially expressed genes in the pigeon ovary. The protein-protein interaction network highlighted genes like HSD11B1, VEGFD, WNT6, SMAD6, and LGR5 as potential contributors to hierarchical follicle selection under RL. This research provides new insights into the molecular basis by which RL may promote hierarchical follicle selection and improve egg production in pigeons.

Is it possible to replace eCG by GnRH in the hormonal protocol for timed artificial insemination in ewes during the breeding season?

Hormonal protocols based on progestogens and equine chorionic gonadotrophin (eCG) are efficient for estrus and ovulation synchronization in ewes. Although eCG is indispensable during seasonal anestrus, it may not be necessary during the breeding season. Thus, we tested the hypothesis that GnRH is effective in replacing eCG during the breeding season allowing satisfactory ovulation rate, luteal function and conception rates after timed artificial insemination (TAI). Ewes (n = 134) with a minimum body condition score of 2.5 (0–5 scale) were treated with intravaginal devices (IVD) containing 60 mg of medroxyprogesterone acetate (MPA) for seven days and received 0.26 mg of sodium cloprostenol at the time of IVD removal. In Exp. 1, at IVD removal, ewes (n = 29) were allocated to three groups: eCG (200 IU at IVD removal; n = 10); eCG+GnRH (200 IU eCG at IVD removal and 4 µg of buserelin 36 h later; n = 10); or GnRH (buserelin 36 h after IVD removal; n = 9). Blood samples were collected 2, 6 and 12 days after TAI moment (54 h after IVD removal), for progesterone (P4) analysis. In Exp 2, the ewes were allocated to eCG (n = 10) or GnRH (n = 10) groups, as above described, and ovulation moment was evaluated 54, 66 and 78 h after IVD removal. In Exp 3, TAI was performed in ewes from eCG (n = 45) and GnRH (n = 40) groups using 100 × 106 motile spermatozoa from a pool of semen collected from four rams. In Exp. 1, based on P4 levels, we confirmed that all the ewes ovulated (29/29) and there was no significant effect of group (P = 0.89) or group x day (P = 0.18) on P4 concentration, being observed a significant effect of day (P = 0.0001). In Exp. 2, the maximum DF diameter (P = 0.26) and ovulation moment (P = 0.69) did not differ between groups. In Exp. 3, pregnancy rate was significantly lower (P = 0.02) in GnRH (22.5 %; 9/40) compared to eCG (46.7 %; 21/45). The results indicate that, although ovulation and luteal function were not altered after eCG, eCG+GnRH or GnRH treatment, GnRH alone before TAI cannot be used to replace eCG treatment during the breeding season.

Can the reduced GH, IGF-1, and ovarian steroids concentrations be considered as suspected biomarkers of age-associated functional deficit in mares?

In humans' and experimental animals’ components of the somatotropic axis, such as growth hormone (GH) and insulin-like growth factor 1 (IGF-1) concentrations, decrease with advancing age. Although there is evidence regarding IGF-1, the effect of age on GH in mares, as well as the relationships between both parameters, have not yet been elucidated. On the other hand, although GH and IGF-1 are related to follicular development, it is unknown if they could be correlated with the circulating concentrations of ovarian steroids in mares, as occurs in other species. The hypothesis of this study was that both GH and IGF-1 could experience physiological changes with advancing age also in mares, and that both GH/IGF-1 could be correlated with oestradiol-17β (E2) and progesterone (P4), as recorded for other species. Hence, the objective of this study was to evaluate the concentrations of GH, IGF-1, E2, and P4 in mares, according to the different ages. Blood samples were drawn from 56 healthy cyclic Spanish Purebred mares belonging to four different age groups: 6–9 years, 10–13 years, 14–16 years and >16 years. Mares aged 6–9 years and 10–13 years showed higher GH concentrations (P < 0.05) than mares of 14–16 and >16 years; and mares aged 14–16 showed higher GH concentrations (P < 0.05) than >16 years (P < 0.05). Mares aged >16 years showed lower IGF-1 concentrations (P < 0.05) than mares of 6–9, 10–13 and 14–16 years (P < 0.05). The concentrations of E2 and P4 showed no significant differences among different age groups. Both GH and IGF-1 were not correlated with each other or with E2 and P4. The concentrations of E2 and P4 did not change with age. Advancing age leads to a decrease in the activity of the somatotropic axis in physiological cyclic mares, represented by a significant GH reduction, which, however, was ascribed for IGF-1 exclusively to mares over 16 years of age, without alterations in steroid hormone patterns.

Reproductive outcomes in Holstein heifers synchronized with timed-AI protocols that provide for a lengthened proestrus.

This study compared reproductive outcomes among two protocols for synchronization of ovulation that provide for a lengthened proestrus with the conventional oestradiol-based protocol currently used for timed-AI (TAI). Holstein heifers (13-15 months) at one location were assigned randomly to one of three TAI protocols. Heifers (n = 150) in the 7-day oestradiol benzoate (EB) group received a progesterone device (Cue-Mate) and 2 mg EB on Day 0; 500 μg of cloprostenol (PGF) and Cue-Mate removal on Day 7; 1 mg of EB on Day 8 and TAI on Day 9 (54 h after Cue-Mate removal). Heifers (n = 150) in the 5-day CO-Synch (CO) group received a Cue-Mate and 100 μg of gonadotropin-releasing hormone (GnRH) on Day 2; Cue-Mate removal and PGF (twice, 12 h apart) on Day 7; and GnRH along with TAI on Day 10 (72 h after Cue-Mate removal). Heifers (n = 150) in the J-Synch (JS) group received a Cue-Mate and 2 mg of EB on Day 1; PGF and Cue-Mate removal on Day 7; GnRH and TAI on Day 10 (72 h after Cue-Mate removal). Heifers were inseminated by one technician with frozen-thawed conventional semen from one of four commercially available sires. Plasma progesterone (P4) concentrations (ng/mL) were determined at Cue-Mate removal and TAI. Ovarian ultrasonography was done in a subset of 217 heifers at the initiation of protocols, at Cue-Mate removal; TAI; and 7 days after TAI. Approximately, 28 and 50 days after TAI pregnancy status was determined by ultrasonography. Mean (±SEM) plasma P4 concentration at Cue-Mate removal was greater (p < .01) in CO (6.02 ± 0.2) and JS (6.51 ± 0.2) compared to EB heifers (4.53 ± 0.2). Mean (±SEM) plasma P4 concentration at TAI was lowest in the JS (0.28 ± 0.05), intermediate in CO (0.46 ± 0.02), and greatest in EB heifers (0.66 ± 0.05, p < .01). The diameter of the ovulatory follicle (mean ± SEM) was the smallest in the JS group compared to that in the CO and EB groups (15.8 ± 0.5; 13.9 ± 0.5; and 12.7 ± 0.5 mm for EB, CO and JS, respectively). More (p < .01) heifers in the JS group had their oestrous cycle synchronized (50.0, 78.8 and 82.4% for EB, CO and JS groups), and were pregnant at 28 (40.3, 51.3 and 63.3% for EB, CO and JS groups) and 50 days after TAI (32.6, 46.0 and 60.0% for EB, CO and JS groups). In summary, heifers subjected to the J-Synch TAI protocol had lower P4 at TAI, and better overall response to hormonal treatments, which resulted in increased P/AI at 28 and 50 days after TAI compared to those heifers subjected to either a 7-day EB protocol or a 5-day CO-synch protocol.