Presence Of Corpus Luteum Research Articles

Can the Presence of Ovarian Corpus Luteum Modify the Hormonal Composition of Follicular Fluid in Mares?

Simple SummaryThe presence of corpus luteum (CL) in the ovary could exert a local differential effect on the hormonal composition of follicular fluid (FF), and it could also indirectly influence follicular development and oocyte quality. Using FF samples of follicles of different sizes in mares, we evaluated the differences between the composition of steroids (oestrogen, androgen and progesterone) in relation to the presence or absence of CL in the ovary. We suggest that FF concentrations of steroid hormones are not only related to follicular size but also to the presence or absence of CL in the ovary.The hypothesis of this study was to investigate if the presence of corpus luteum (CL) in one ovary could modify the hormonal content of follicular fluid (FF) in the follicles. Sixty ovaries were taken after the slaughter of 30 clinically healthy mares. In relation to the sizes, the follicles were classified into three different categories, as small (20–30 mm), medium (31–40 mm) and large (≥41 mm). Blood samples were collected from the jugular vein of mares before their slaughter, and then the FF samplings were extracted from each single follicle. The ovaries that were collected were classified into two groups, according to the presence (CL-bearing) or absence (non-CL-bearing) of CL. The serum and FF samples were analysed for progesterone (P4), oestradiol-17β (E2), testosterone (T), androstenedione (A4) and dehydroepiandrosterone (DHEA). Intrafollicular P4 concentrations in large follicles of CL-bearing groups were lower than for non-CL-bearing ones. Intrafollicular E2 concentrations increased with the increase of the follicle diameter in both groups, CL-bearing and non-CL-bearing. However, in the FF with a large and medium follicle size, E2 concentrations were significantly higher in non-CL-bearing groups than in CL-bearing groups. T and A4 significantly increased in the large and medium follicle sizes when compared to the small follicle sizes in both groups, but higher concentrations in the non-CL-bearing group were obtained. Intrafollicular DHEA significantly decreased with the increase of the follicular diameter in both groups. Steroid hormones in FF dynamically changed, according to the presence or not of CL in the ovary. This study brings new knowledge on the role of the CL in the follicular hormonal composition in mares.

Presynchronization with CIDR, with or without GnRH, prior to CO-Synch in beef heifers

Objectives were to compare ovarian responses and pregnancy per AI (P/AI) in Angus-cross beef heifers (n = 521; 4 locations) synchronized with CIDR–CO–Synch (CCOS) versus CIDR-GnRH–CO–Synch (CGCOS) protocols. Heifers were assigned a reproductive tract score (RTS: 1, immature, acyclic; 5, mature, cyclic), body condition score (BCS: 1, emaciated; 9, obese) and temperament score (0, calm, 1, excitable). Heifers in the CCOS (n = 261) group received a CIDR on Day −20 (removed on Day −13), 100 μg GnRH on Day −10, 25 mg PGF2α on Day −3 and were timed inseminated 60 h later, with concomitant GnRH (Day 0). Heifers in the CGCOS (n = 260) group received a CIDR on Day −26 (removed on Day −19), 100 μg of GnRH on days −16 and −10, 25 mg of PGF2α on Day −3 and were timed inseminated 60 h later, with concomitant GnRH (Day 0). Ovarian ultrasonography was done in a subset of heifers (n = 60; 30 in each group) to determine number and size of ovarian follicles and presence of corpus luteum (CL). There was increased (P < 0.05) percentage of heifers with CL in CGCOS group compared to heifers in CCOS group on Day −10 (82.3 vs 68.2%) and on Day −3 (88.3 vs 75.1%). Average size of the largest ovarian follicle on Day 0 was greater for heifers in CGCOS group compared to CCOS group (P < 0.05). However, P/AI did not differ between CCOS and CGCOS groups, 55.0% (143/260) and 59.8% (156/261), respectively (P > 0.1). In conclusion, CIDR presynchronization with or without GnRH (CCOS and CGCOS protocols) in beef heifers resulted in similar P/AI. Adding GnRH to presynchronization with CIDR resulted in more heifers with a CL at PGF2α and increased preovulatory follicle diameter at AI. Future studies are needed with bigger sample size and CIDR + CO-Synch treatment as control to determine economic benefit.

Ultrasonographic evaluation of the reproductive tract as predictors of pregnancy in Girolando heifers submitted to Timed Artificial Insemination

The objective of this study was to evaluate the influence of the degree of uterine and ovarian development on the pregnancy rate of Girolando heifers submitted to Timed Artificial Insemination (TAI). Fifty-six heifers, representing 100% of the category in the herd studied, were evaluated. The heifers were submitted to a gynecological evaluation, prior to hormonal treatment, with ultrasonography, in order to measure the diameter of the uterine horns and ovaries, as well as evaluate the presence of corpus luteum (CL) and antral follicles. According to the values found for the uterine and ovarian diameters, the animals were classified into scores from one to three. After the gynecological evaluation, all animals were submitted to TAI. There was no statistical difference (P>0.05) in pregnancy rates between the different uterine and ovarian scores, as well as in relation to ovarian structures. However, a statistical difference (P<0.05) was observed in the percentage of animals in anestrous within ovarian scores one, two and three (83.3%, 37.5% and 42.8%, respectively). The conclusion was that uterine and ovarian development did not interfere in the pregnancy rate of Girolando heifers in the herd studied.

299 Treatment with prostaglandin F2α and an intravaginal progesterone insert in advance of gonadotropin-releasing hormone enhances response to estrus synchronization in mature beef cows

Abstract An experiment was designed to evaluate the effect of treatments in advance of gonadotropin-releasing hormone (GnRH; 100μg gonadorelin) administered at the start of estrus synchronization. We hypothesized that administration of prostaglandin F2α (PG; 500μg cloprostenol) followed by treatment with an intravaginal progesterone-releasing insert (CIDR; 1.38g progesterone) would result in increased follicle size at GnRH, thereby enhancing response to GnRH and overall response to estrus synchronization. Postpartum suckled beef cows (n = 183) in two locations were assigned to one of five treatments based on age, days postpartum, and body condition score. Treatments (Figure 1) were designed as a two-by-two factorial with a control (Treatment 1). Treatments 2–5 received a CIDR insert from Day -17 to Day -10, with (Treatments 2 and 3) or without (Treatments 4 and 5) administration of PG coincident with CIDR insertion on Day -17. Coincident with GnRH administration on Day -10, CIDR inserts were either removed (Treatments 2 and 4) or remained in place until Day -3 (Treatments 3 and 5). On Day -3, estrus detection aids were applied and a representative subset of cows in each treatment were fitted with estrus detection transmitters. Blood samples were collected on Days -27, -17, -10, -3, and 0 for determination of serum estradiol and/or progesterone concentrations via radioimmunoassay. For a representative subset of cows (n = 111), transrectal ovarian ultrasound was performed to assess ovarian follicle size and presence of corpora lutea on Days -17, -10, -3, and 0. Treatment with PG and CIDR in advance of GnRH resulted in improvements (P &amp;lt; 0.05) in several response variables, including follicle size on Day -17 and estrous response prior to AI. Results support the hypothesis that administration of PG and treatment with a CIDR for 7 d prior to GnRH improves likelihood of GnRH response and enhances response of mature cows to estrus synchronization.

166 Comparison of the 7 and 7 Synch protocol and the 7-day CO-Synch + controlled internal drug release protocol among recipient beef cows in an embryo transfer programme

An experiment was designed to evaluate the effectiveness of the recently developed 7 and 7 Synch protocol to synchronise oestrus and ovulation among recipients before embryo transfer (ET). Postpartum beef cows (n=1358) across 13 locations were assigned to either the 7-day CO-Synch + controlled internal drug release (CIDR) protocol or the 7 and 7 Synch protocol before oestrus detection and subsequent ET. Cows were pre-assigned to balanced treatments within location based on age and days postpartum, and body condition score was recorded at ET. Cows assigned to the 7-day CO-Synch + CIDR protocol were administered gonadotrophin-releasing hormone (GnRH; 100µg of gonadorelin acetate) on Day 0, an intravaginal CIDR insert (1.38g of progesterone) from Day 0 to 7, and prostaglandin F2α (PG; 25mg of dinoprost tromethamine) coincident with CIDR removal on Day 7. Cows assigned to the 7 and 7 Synch protocol were administered PG (25mg of dinoprost tromethamine) coincident with CIDR insertion on Day −7, GnRH (100µg of gonadorelin acetate) on Day 0, and PG (25mg of dinoprost tromethamine) coincident with CIDR removal on Day 7. The 7 and 7 Synch protocol was hypothesised to enhance response to GnRH administration on Day 0 among mixed groups of oestrous cycling and anestrous cows, ultimately resulting in improved oestrous response and synchrony of oestrus before ET. Cows were observed for visible signs of oestrus following oestrus synchronisation, with GnRH (100µg of gonadorelin acetate) administered to cows failing to express oestrus during the detection period. Length of the detection period varied among locations but was consistent across treatments within location. Embryo transfer was performed approximately 7 days after oestrus or GnRH administration. Presence of corpora lutea (CL) was determined via transrectal palpation by a single veterinarian blinded to treatment, and embryos were transferred only to cows with palpable CL. Embryo transfer was performed using fresh or frozen embryos staged and graded according to IETS recommended guidelines, with embryo information recorded for each recipient. Data were analysed using the PROC GLIMMIX procedure of SAS (SAS Institute Inc.). Proportion of cows expressing oestrus was improved (P&amp;lt;0.0001) among cows assigned to the 7 and 7 Synch protocol (86% (529/615) vs. 76% (488/640)). The proportion of recipient females with palpable CL tended to be greater (P=0.07) among cows assigned to the 7 and 7 Synch protocol (82% (478/586) vs. 80% (451/565)). Among cows that expressed oestrus, a greater proportion (P&amp;lt;0.01) had palpable CL following the 7 and 7 Synch protocol (88% (466/529) vs. 86% (418/488)). Consequently, irrespective of embryo type received, the proportion of recipients pregnant to ET was greater (P&amp;lt;0.01) following the 7 and 7 Synch protocol (39%; 263/668) compared with the 7-day CO-Synch + CIDR protocol (33%; 228/690). In summary, the 7 and 7 Synch protocol improved the likelihood of oestrus expression in recipient cows, increased the proportion eligible to receive an embryo, and resulted in greater pregnancy rate to ET.

Impact of Corpus Luteum Presence or Absence in the Incidence of Preeclampsia After Frozen Embryo Transfer

Impact of Corpus Luteum Presence or Absence in the Incidence of Preeclampsia After Frozen Embryo Transfer

Economic evaluation of puberty induction of nulliparian Nellore heifers using intravaginal device and melengestrol acetate

The present study evaluates the economic viability of puberty induction in nulliparous Bos taurus indicus Nellore breed heifers using an intravaginal device of fourth-use and melengestrol acetate (MGA®). The experiment was undertaken in the Nossa Senhora Aparecida Farm, Terenos city, Mato Grosso do Sul, Brazil, and was utilized a completely randomized experimental design in a 2 × 3 factorial scheme. Two age classes were included in the study, which were divided into 348 precocious (early-cycle) heifers, aging 16-18 months, weighting an average of 264.6 kg and 543 conventional-cycle heifers aging 24-26 months averaging 346.8 kg. The three treatments were as follows: control without the induction of follicle formation (treatment 1); treatment 2: induction with an intravaginal implant (intravaginal implantation with a fourth-use progesterone implant on Day 0, withdrawal on Day 12, and application of 1 ml of intramuscular estradiol cypionate [ECP®]); and treatment 3, 2.3 g of MGA® during 12 days with supplement followed by 1 ml of intramuscular ECP® at the end of the treatment. Heifers induced via implantation had a higher rate of ovarian activity (presence of corpus luteum) during the early cycle (63.8% animals) while the conventional cycle (72.4%). This effect influenced the frequency of early stage anestrus (56%). Among the treatments evaluated, 72% of control heifers had no ovarian activity (absence of corpus luteum). In the group with implant induction the conception rates were 65.5% and 62.4% in early and conventional-cycle females, respectively. Puberty induction in Nellore heifers provides a high economic return. The protocol revealed highest efficiency compared to the control group.

Association of menstruation cycle with completed suicide: a hospital-based case-control study.

The purpose of the study was to determine the phases of the menstrual cycle in the reproductive age group of females who committed suicide as compared with a control group of females who died from causes other than suicide. The study included 86 cases in the suicidal group and 80 cases in the non-suicidal group. The menstrual phase was decided by the gross and histological examination of the uterus and ovary at autopsy. Deaths were more common during the secretory phase (56.9%) in the suicidal group, while in the non-suicidal group, death occurred more commonly in the proliferative phase (66.3%). In reference to proliferative phase, deaths were more in the secretory phase and menstrual phase in the suicidal group, adjusted odd's ratio (OR) being 3.7 (p = 0.042) and 4.7 (p = 0.032), respectively. Corpus luteum was present in the right ovary of 43 and 14 victims of suicidal and non-suicidal deaths, respectively, while it was in the left ovary of 3 and 11 victims of suicidal and non-suicidal death, respectively. Odd's ratio was 10.3 for corpus luteum to be in the right ovary in comparison with the left ovary for the suicidal group (p = 0.001). This study revealed that suicidal chances in a woman are significantly more in the menstrual phase and the secretory phase of the menstrual cycle. The presence of corpus luteum in the right ovary is associated with an increased risk of suicide, but the reason is not known.

Productive and Reproductive Perfomance of Dairy Cows During Peripartum

ABSTRACT Dairy activity is of great importance for the national economy. It is also an important source of income for families in the south east region of Parana that work in this area. There has been a notable expansion in the activities as well as in the quantity of production and the quality of the products. With this has come problems in the reproductive efficiency of the dairy cattle principally in relation to those with the greatest production. The objective of this study was to evaluate the productive profile and the reproductive efficiency of dairy cows. The evaluation covered 30 days before calving and 15, 30, 45, 60 and 90 days after the calving. The study covered cows from two properties in the Municipality of Realza-PR in Brazil. In order to do the aforementioned, we used the Body Condition Score (BCS). We evaluated the production of milk and through the use of gynecological exams and we looked at uterine involution (UI) and ovarian cyclicality. The results showed falls in the BCS in the prepartum period and in the first weeks of lactation (p<0.05) and the differences in the BCS were based on the season of the year in which the calving took place (p<0.05) with the highest BCS being noted to occur in the hot seasons. The UI correlates with the presence of corpus luteum where animals were late in their uterine involution and had delays in their first postpartum ovulation (p<0.05). The average service period and calving interval were similar to those described for dairy cattle, however, we observed variations based on the seasons of the year which was possibly related to the greater availability and quality of the forage in the hot seasons.

The combination of β-carotene and vitamins improve the pregnancy rate at first fixed-time artificial insemination in grazing beef cows

The aim of this experiment was to evaluate the effects of feeding the combination of β-carotene and vitamins (ADE and biotin) on reproductive performance of grazing beef cows. A total of 430 suckled multiparous Nellore cows (Bos indicus, initial body weigh = 417 ± 58 kg) were used in a randomized block design. At the beginning of the trial (30 days before fixed-time artificial insemination - FTAI) animals were assigned according to calving date, body condition score (BCS) and blocked according to blood β-carotene concentration. Treatments were: Control (mineral supplement: no β-carotene and vitamins) and Treated (combination of 500 mg β-carotene, 70,000 IU Vit. A, 10,000 IU Vit. D3, 500 mg Vit. E and 10 mg biotin/cow/day into the mineral supplement). Animals were synchronized using estradiol/progesterone (E2/P4) based protocol. Pregnancy rate was evaluated 30 days after FTAI and 30 days after the end of breeding season. No difference in the cyclicity rate [presence of corpus luteum (CL); P = 0.31] before FTAI synchronization protocol on day 11 was observed. The percentage of cows in estrus between P4 device removal and FTAI did not differ between groups at first (P = 0.39) and second FTAI (P = 0.18). The combination of β-carotene and vitamins into the mineral supplement increased the pregnancy rate at first FTAI: Control: 57.6% (125/217) vs. Treated: 66.7% (142/213; P = 0.04) but not at second FTAI: Control: 55.4% (51/92) vs. Treated: 50.7% (36/71; P = 0.52) and to the natural mating: Control: 46.3% (19/41) vs. Treated: 31.4% (11/35; P = 0.07) or at the end of breeding season Control: 89.9% (195/217) vs. Treated: 88.7% (189/213; P = 0.77). In the non-pregnant cows, the occurrence of CL did not differ between groups at first (P = 0.93) and second (P = 0.89) pregnancy diagnostics. Treated cows had greater embryo thoracic width at second pregnancy diagnostic compared to Control cows (P = 0.003). Positive correlations were observed between the pregnancy rate at first FTAI (day 30) and BCS at day 11 (P = 0.05), largest follicle at day 2 (P = 0.01), and blood β-carotene concentration on day -11 (P = 0.06) of FTAI protocol. Including the combination of β-carotene, vitamins ADE and biotin into mineral supplement for grazing beef cows increases the conception rate at first FTAI and can be a tool to optimize the reproductive performance.

Importance of body condition score and ovarian activity on determining the fertility in beef cows supplemented with long-acting progesterone after timed-AI

The working hypothesis was that supplementation with progesterone (iP4) at early diestrus increases pregnancy rates of suckled beef cows with poor body condition score (BCS) and/or in anestrus when cows are submitted to timed insemination (TAI). The time of ovulation among suckled multiparous (n = 1270) and primiparous (n = 303) Nelore cows was synchronized using an estradiol/P4-based protocol for TAI (D0). At Day ‒10, visual evaluation of BCS was performed (scale = 1–5) and animals were classified according to an ovarian activity (OA) score: (OA1) absence of CL and presence of follicles ≥ 8 mm, (OA2) absence of CL and presence of follicles < 8 mm and (OA3) presence of corpus luteum (CL). On Day 4, animals were assigned randomly to receive 150 mg of injectable, long-acting P4 (iP4, n = 786) or non-iP4 (n = 787). Further, ultrasonic evaluations were performed on D0 and D4 for measurements of the largest follicle diameter (DF) and CL area, respectively. The BCS affected positively DF, CL area and OA. Supplementation with iP4 did not affect (P = 0.49) pregnancy rates and there was no significant interaction (P > 0.1) of P4 treatment with BCS or OA was detected for conception and pregnancy rates. Regardless of iP4, pregnancy rates of cows with moderate (2.75–3.25) (59.1%) and high (≥ 3.5) (57.8%) BCS were greater than those of cows with low (2.0–2.5) BCS (41.5%). Cows in OA2 had a greater P/AI (51.3%) than cows in OA1 (41.7%) or OA3 (41.9%). In conclusion, P4 supplementation after TAI did not improve P/AI and did not enhance the response to treatment of cows with a low BCS, regardless of OA.

Lysophosphatidic acid enhances PGE2 to PGF2α ratio and nitric oxide level in nonpregnant buffalo uterus

Lysophosphatidic acid (LPA) is a small ubiquitous lipid exerting diverse biological functions. Its role in reproduction in different species has created great interest in recent times. In the present study, we aimed to elucidate LPA signaling in nonpregnant buffalo uterus by in vitro studies. Standard techniques like real-time PCR (for mRNA expression of LPARs and COX-2 and iNOS), Western blot (for PPARγ protein expression), sandwich ELISA (for PGE2 and PGF2α assay) and histopathology (for assessment of endometrial architecture in culture) were used in this study. The buffalo uterine tissues were collected from the local slaughterhouse and were selected for the study on the basis of the presence of corpus luteum on the ovary (n = 5). The LPAR3 receptor was the highest expressed receptor as compared to LPAR1 and LPAR6 in non-pregnant uterine tissues after 6 h incubation in Dulbecco's Modified Eagle Medium (DMEM). 50 μM LPA increased the mRNA expressions of COX-2 and iNOS enzymes which were attenuated by the treatment of LPAR1/3 antagonist Ki16425. PPARγ antagonist GW9662 prevented the LPA-induced increase in iNOS mRNA expression but did not alter the COX-2 expression. LPA also enhanced the PGE2 to PGF2α ratio in uterine tissue homogenates which was inhibited by all the receptor antagonists as well as by the inhibitors of COX-2 and iNOS. LPA also increased the total nitrite level in tissue homogenates in LPAR1/3- and iNOS-dependent manner. Additionally, we demonstrate PPARγ mRNA and protein expressions in nonpregnant buffalo endometrium. In conclusion, the results of the present study suggest that LPA acts as a luteotropic factor during the estrus cycle in nonpregnant buffalo uterus by enhancing PGE2 to PGF2α ratio and NO level through multiple receptors.

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

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

Sexual precocity and productivity of beef cattle female under grazing conditions

In view of the importance of female reproductive traits as a key profit indicator in beef-cattle production systems, the objective of the present study was to explore the relationships between female sexual precocity and potential predictive traits of easy and early measurement, related to the productive and reproductive efficiency. Heifers born in 2011 and 2012 (n = 132) from five genetic groups (Angus, Hereford, Angus-Hereford, Hereford-Angus and Argentine Creole) in 2 years (Trial 1 and Trial 2) under grazing conditions were evaluated. After weaning, the presence of corpus luteum, liveweight, body condition score, hip height, rump fat thickness and rib fat thickness were recorded every 28 days, and Longissimus muscle area at 15 months of age. Also, to evaluate the relationships between age at puberty and the subsequent production efficiency, the annual records of 895 cows (217 Angus, 253 Hereford, 125 Creole, 116 Angus-Hereford and 184 Hereford-Angus) born between 1986 and 2009 were studied to estimate the average annual productivity of cows, and its components of (Co)variance, heritability and breeding values. Nutritional conditions immediately after weaning were determinants in reaching puberty. The univariate animal model for average annual productivity showed a heritability of 0.14 ± 0.05. Regression multiple and covariance analyses revealed that the rib fat thickness at 450 days of age was a good predictor of age at puberty, but lose some relevance as early selection criterion. Finally, it is important for future studies to analyse in more detail the existence of critical thresholds of fat deposition for the onset of reproductive activity.

Efficacy of different methods for detecting the onset of ovarian cyclicity in post-partum Murrah buffaloes.

This study was designed to investigate the sensitivity and specificity of three methods for detecting the onset of cyclicity in post-partum Murrah buffaloes. The methods investigated were visual signs, transrectal ultrasonography, and serum progesterone (P4) assay. For this study, 102 post-partum Murrah buffalo cows were grouped for monitoring their ovarian activity. The first group of buffaloes was between 26 and 35days post-partum. Thereafter, the buffalo cows that calved were grouped after every 10days for the study sample. Thus, the study animals were adjudged between 26 and 35, 36-45, 46-55, 56-65, 66-75, 76-85, and 86-95days post-partum with an average of 30, 40, 50, 60, 70, 80, and 90days post-partum, respectively. Visual estrus signs were monitored twice daily, and simultaneously, ultrasound examination was carried out at 10days interval for accessing the presence of corpus luteum (CL). Serum P4 was estimated in the animals which were adjudged cyclic by ultrasound examination, and the assay was repeated after 10days. The buffalo cows in estrus were inseminated artificially, and pregnancy status was assessed after 30days post-insemination. In this study, the sensitivity and specificity of visual observation were low (39.37 and 70.73%, respectively) when compared to P4 assay (98.80 and 96.47%) and ultrasound examination (single, 97.59 and 97.59%; double, 100 and 100%), respectively. Furthermore, the sensitivity and specificity of single and double ultrasound examination and P4 assay were comparable. In conclusion, this study reports that single and double ultrasound examination and P4 assay are more efficient than visual observation in detecting the onset of ovarian cyclicity in post-partum Murrah buffaloes.

Association between hormonal and structural changes of the reproductive tract in estrus dairy cows

Normal cyclic changes in hormonal and ultrasonic echotexture along with estrus are critical for successful breeding in dairy cows. We studied relationships among steroid hormone concentrations and ultrasound changes of uterus and ovaries just before insemination in heat dairy cows. Eighty-nine estrus dairy cows were selected for transrectal examination of uterus and ovaries, and blood sampling just before AI. Ultrasound characteristics of the uterus and ovarian structures were recorded. The concentration of estrogen, progesterone, and cortisol was measured in serum of estrus cows. Our results showed that there was not any relationship between ultrasound findings of uterus and steroid hormones in heat dairy cows. Also, there was no correlation between serum progesterone, estradiol, and cortisol concentrations with the diameter of dominant follicle. In addition, it was found that there was no correlation between serum progesterone, cortisol concentrations, and the presence of corpus luteum (CL) on ovary in heat cows, but there was a negative significant relationship between the presence of CL and estradiol concentration (r = − 0.21, P = 0.04). Association between ultrasound characteristics of the uterus and steroid hormone (estradiol, progesterone, and cortisol) concentrations were not significant and considerable in estrus dairy cows.

Follicular dynamics, circulating progesterone, and fertility in Holstein cows synchronized with reused intravaginal progesterone implants that were sanitized by autoclave or chemical disinfection

This experiment aimed to compare circulating progesterone (P4), follicular dynamics, and fertility during reuse of intravaginal P4 implants that were sanitized by autoclave or chemical disinfection in lactating Holstein cows submitted to fixed-time artificial insemination (FTAI). For this, 123 primiparous and 226 multiparous cows from 2 farms, averaging (mean ± standard deviation) 163.9 ± 141.9 d in milk, 35.7 ± 11.3 kg of milk/d, and a body condition score of 2.9 ± 0.5, were enrolled in the study. Cows were randomly assigned to 1 of 2 treatments using a completely randomized design and each cow received a reused implant (1.9 g of P4; previously used for 8 d) that was either autoclaved (AUT; n = 177) or chemically disinfected (CHEM; n = 172) on d -10. Also on d -10, cows received 2 mg of estradiol benzoate and 100 μg of GnRH. On d -3, cows received 25 mg of dinoprost (PGF2α). A second PGF2α was given on d -2, along with 1 mg of estradiol cypionate and P4 implant removal. Cows received FTAI on d 0. A subset of cows (n = 143) was evaluated by ultrasound on d -10, -8, -6, -3, -2, 0, and 5 to identify ovarian structures, and blood was sampled on d -10, -3, and -2 for P4 concentrations by RIA. Pregnancy diagnoses were performed at d 32 and 60. Statistical analyses was performed using PROC-MIXED for continuous variables and PROC-GLIMMIX of SAS 9.4 (SAS Institute Inc., Cary, NC) for binomial variables. The treatments did not differ in circulating P4 on d -10 or -3, but P4 was greater on d -2 in CHEM cows. Ovulation to the treatments on d -10 was associated with lower circulating P4 on d -10 (2.0 vs. 3.1 ng/mL) and resulted in greater P4 on d -3 (4.0 vs. 2.4 ng/mL) and more cows with a corpus luteum on d -3 (100 vs. 40%) than nonovulating cows. Cows that ovulated to d -10 treatments were more likely to have a synchronized new follicular wave (97.9 vs. 63.2%) and had an earlier wave emergence (1.9 vs. 2.6 d), resulting in less cows ovulating a persistent follicle (0.0 vs. 35.7%). Type of P4 implant, corpus luteum presence on d -10, and ovulation to d -10 treatments did not affect fertility (pregnancy per AI; P/AI). However, P/AI on farm A was greater than on farm B at 32 (40.8 vs. 27.8%) and 60 d (35.8 vs. 24.3%), independent of treatment. In conclusion, P4 implants with different P4 release patterns did not produce detectable differences in follicular dynamics, synchronization rate, or P/AI. Nevertheless, presence of corpus luteum or ovulation at the beginning of the FTAI protocol affected reproductive variables, such as timing and synchronization of follicular wave emergence, and size of the ovulatory follicle. Beyond that, more overall synchronized cows became pregnant to the FTAI protocol.

Biostimulation in primiparous postpartum acyclic early weaned beef cows: introducing the bulls at weaning advances cyclic rebreeding.

Weaning and biostimulation promote an early cyclic postpartum rebreeding. Although the signals and mechanisms by which weaning and biostimulation differ, both end stimulating LH secretion. The aim of the experiment was to determine if weaning and biostimulation have additive effects advancing the postpartum rebreeding in primiparous postpartum anoestrous cows. The experiment was performed during late spring – early summer with 51 primiparous Hereford cows. Six weeks after parturition calves were weaned, and cows were managed in two experimental groups: WB (n = 22) and WDB (n = 29). Bulls were joined with WB cows at weaning, but joining was delayed one week in WDB cows. The presence of corpora lutea in the ovaries was recorded weekly with ultrasound, and 28 and 50 days after the end of the exposure period, pregnancy was determined by ultrasound. The percentage of cyclic cows was greater in WB than in WDB on Weeks 8 (36.4 vs 0%), 9 68.2 vs 13.8%), 10 (86.4 vs 27.6%) and 11 (100.0 vs 37.9%) (P < 0.001 in all). Cows that were weaned and biostimulated simultaneously rebred earlier than WDB cows (Week 9.1 ± 0.2 vs Week 11.0 ± 0.2; P < 0.0001). At the end of the experiment 46/51 (90.2%) of the animals were cycling. Pregnancy rate tended to be greater in WB than WDB cows 28 days after the end of the breeding period 18/22 vs 17/29, P = 0.077), but there was no difference at the end of the study (20/22 vs 24/29, ns). In conclusion, the application of weaning and biostimulation simultaneously advances postpartum rebreeding more than weaning alone in beef cows.

Effect of presence of corpora lutea on cumulus expansion of in vitro matured bovine oocytes selected by trypan blue and brilliant cresyl blue tests

ABSTRACTTrypan Blue (TB) and Brilliant Cresyl Blue (BCB) are used to select and determine viability and competence of oocytes, however, the effects of corpora lutea on cumulus expansion during in vitro maturation are still undetermined. Cumulus-oocytes complexes (COCs) from ovaries with ipsilateral (ICL), contralateral (CCL) and without corpora lutea in either ovary (OCL) were selected by visual examination, TB and BCB staining, and matured in vitro to evaluate cumulus expansion. The overall percentage of visually selected COCs was similar in ICL, CCL and OCL (P > 0.05). Proportions of live and mature COCs were similar in all groups (P > 0.05). The overall percentage of BCB+ COCs was 70.1%. BCB+ ICL COCs had less cumulus expansion (60.5%) than BCB+ CCL and OCL COCs (75.7 and 71.4%, respectively; P < 0.01). BCB− ICL COCs had less cumulus expansion (20.0%) than BCB− CCL and OCL (39.7 and 46.1%; P < 0.01). BCB+ CCL and OCL COCs showed the highest cumulus expansion index (P < 0.01). Presence of corpus luteum in the ovary affects negatively cumulus cells expansion. TB and BCB staining facilitate the selection of oocytes with higher degrees of cumulus expansion.

13 Pre-synchronization by Induction of a Dominant Follicle Using a Progesterone Device in a GnRH-Based-Ovulation Synchronization Protocol in Lactating Dairy Cows

The objective was to compare a pre-synchronization protocol by induction of a dominant follicle using a progesterone intravaginal device before an Ovsynch protocol (Presynch) with Double-Ovsynch in lactating dairy cows. Lactating Bos indicus × Bos taurus crossbred cows (n = 440) were randomly allocated to 1 of 2 treatments (all IM injections): (1) Double-Ov (n = 228): GnRH (Day –17), prostaglandin F2α (PGF2α) 7 days later (Day –10) and gonadotropin-releasing hormone (GnRH) 3 days later (Day –7) followed by an Ovsynch protocol 7 days later (GnRH on Day 0, PGF2α on Day 7, GnRH on Day 9); (2) Presynch (n = 212): insertion of a sustained release progesterone intravaginal device (Day –10), 10 days later (Day 0), an Ovsynch protocol was initiated with progesterone device withdrawal on Day 7. All cows were artificially inseminated 15 to 20 h after the second GnRH injection of the Ovsynch protocol and were pregnancy checked by ultrasonography 30 and 60 days later. On a subsample (n = 102), ultrasonography was performed on Days 0, 7, 9, and 24 of the experimental period. On another subsample (n = 42), blood samples for progesterone analysis were taken on Days 0, 7, and 24. There were no differences between pre-synchronization methods on synchronization parameters [presence of a follicle &gt;12 mm on D0, Double-Ov 94.2% (49/52) and Presynch 92.0% (46/50); P = 0.66], follicular diameter on the 1st GnRH (Double-Ov 17.2 ± 0.7 mm and Presynch 18.6 ± 0.9 mm; P = 0.28), ovulation rate to the 1st GnRH [Double-Ov 86.3% (44/51) and Presynch 81.2% (39/48); P = 0.50], synchronization rate [Double-Ov 84.6% (44/52) and Presynch 86.0% (43/50); P = 0.84], follicular diameter on the 2nd GnRH (Double-Ov 17.5 ± 0.6 mm and Presynch 18.0 ± 0.5 mm; P = 0.48), ovulation rate to the 2nd GnRH [Double-Ov 90.9% (40/44) and Presynch 86.0% (37/43); P = 0.48] and CL diameter on Day 24 (Double-Ov 27.9 ± 0.7 mm and Presynch 29.4 ± 0.9 mm; P = 0.19). Corpus luteum presence on Day 0 was different (P = 0.03) between treatments [Double-Ov 57.7% (30/52) and Presynch 36.0% (18/50)]. Moreover, there was no difference (P = 0.85) between pregnancy rates on Day 30 [Double-Ov 39.0% (89/228) and Presynch 40.1% (85/212)] or Day 60 after AI [Double-Ov 34.8% (79/227) and Presynch 38.7% (82/212); P = 0.41] and gestational loss between 30 and 60 days after AI [Double-Ov 7.9% (7/88) and Presynch 3.5% (3/85); P = 0.13]. Proportion of cows with P4 &lt;1 ng mL−1 on Day 0 was similar between treatments [Double-Ov 13.6% (3/22) v. Presynch 5.0% (1/20); P = 0.37]. Likewise, the proportion of cows with P4 &gt;1 ng mL−1 on Day 7 [Double-Ov 77.3% (17/22) v. Presynch 95.0% (19/20); P = 0.14] and P4 concentration on Day 24 (Double-Ov 4.7 ± 0.6 v. P4-Ov 5.9 ± 0.9; P = 0.84) were similar between treatments. In conclusion, pre-synchronization by induction of follicular persistence using a sustained-release progesterone device before Ovsynch yielded similar results to the Double-Ovsynch protocol on follicular development and regression patterns and on the fertility of lactating dairy cows.