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Jose Luiz Moraes Vasconcelos - One of the best experts on this subject based on the ideXlab platform.

  • plasma concentrations of progesterone in the preceding estrous cycle are associated with the intensity of Estrus and fertility of holstein cows
    PLOS ONE, 2021
    Co-Authors: A M L Madureira, Jose Luiz Moraes Vasconcelos, T A Burnett, S Borchardt, W Heuwieser, Christine F Baes, R L A Cerri
    Abstract:

    The aim of this study was to determine the association between concentrations of progesterone (P4) during previous the estrous cycle with the intensity of spontaneous or estrogen-induced estrous expression and pregnancy per artificial insemination (P/AI). A total of 1,953 AI events from lactating Holstein cows were used, consisting of 1,289 timed AI events from experiment 1 (Exp. 1) and 664 AI events from experiment 2 (Exp. 2). In Exp. 1, cows were bred after a timed AI protocol based on estradiol and P4. In Exp. 2 animals were bred upon spontaneous Estrus detection. In both experiments cows were continuously monitored by an automated activity monitor (AAM), in Exp.1 a relative increase of activity was calculated (i.e., percentage of increase activity at Estrus compared to cow's baseline activity) and in Exp.2, activity data from each cow were computed into an index value that ranged from 0 to 100. In Exp.2 duration (hours) of Estrus were calculated and defined as the total time above the threshold (35 index). The intensity of estrous expression was determined for each event and classified as either high or low intensity using the median of each experiment. Blood samples were collected for P4 analysis in Exp. 1 at -4 d, 0 d, and 7 d relative to timed AI, and in Exp. 2 immediately following Estrus (0 d), 7 d, 14 d, and 21 d post-AI. Concentration of P4 was classified as greater or lower according to the median value in each experiment. Cows with lower concentrations of P4 at AI had greater estrous expression in Exp. 1 (363.6 ± 5.2 vs. 275.9 ± 8.0% relative increase) and Exp. 2 (76.7 ± 1.9 vs. 67.4 ± 4.7 index; and 12.5 ± 0.5 vs. 9.3 ± 1.8 hours). Cows with a greater intensity of estrous expression at timed AI had greater concentrations of P4 at -4 d than cows with lower intensity Estrus or no estrous expression (4.6 ± 0.2 vs. 3.6 ± 0.2 vs. 3.7 ± 0.2 ng/mL). Cows with greater concentrations of P4 at -4 d had greater P/AI (32.8 ± 4.4 vs. 22.4 ± 4.5%), whereas cows with lesser concentrations of P4 at d0 for either timed AI (35.2 ± 3.4 vs. 19.6 ± 4.6%) or spontaneous Estrus (31.8 ± 2.8 vs. 23.4 ± 3.2%) had greater P/AI. Cows with greater concentrations of P4 7 d post-timed AI had greater P/AI compared with cows that had lower concentration of P4 (39.1 ± 2.9 vs. 24.7 ± 2.6%). Similarly, cows that had lower concentrations of P4 at 7 d, 14 d and 21 d post-spontaneous Estrus tended to have lower P/AI when compared with cows with greater concentrations of P4. Overall, concentrations of P4 prior to and at AI were associated with greater estrous intensity and P/AI at both spontaneous and timed AI events.

  • expression of Estrus modifies the gene expression profile in reproductive tissues on day 19 of gestation in beef cows
    Theriogenology, 2016
    Co-Authors: Saeideh Davoodi, Jose Luiz Moraes Vasconcelos, R F Cooke, Artur Cezar De Carvalho Fernandes, B I Cappellozza, R L A Cerri
    Abstract:

    The aim of this study was to test the effect of expression of Estrus at artificial insemination (AI) on endometrium, conceptus, and CL gene expression of beef cows. Thirty-six multiparous nonlactating Nelore cows were enrolled on an estradiol- and progesterone (P4)-based timed AI protocol (AI = Day 0) and then slaughtered for the endometrium, CL, and conceptus collection on Day 19. The animals were retrospectively grouped on the basis of cows that (1) showed signs of Estrus near AI (n = 19; Estrus) and (2) did not show any signs of Estrus (n = 17; nonEstrus). Body condition score, blood sampling, and ultrasound examination were performed on Days 0, 7, and 18 of the experiment followed by messenger RNA extraction and quantitative reverse transcription polymerase chain reaction analysis of 58 target genes. Data were checked for normality and analyzed by ANOVA for repeated measures using proc GLM, MIXED, and UNIVARIATE of SAS. Only pregnant cows were included in the analyses (n = 12; nonEstrus, n = 11). Estrous expression had no correlation with parameters such as body condition score, preovulatory follicle and CL diameter, P4 concentration in plasma on Days 7 and 18 after AI, and interferon-tau concentration in the uterine flushing (P > 0.15); however, a significant increase was observed in conceptus size from cows that expressed Estrus (P = 0.02; 38.3 ± 2.8 vs. 28.2 ± 2.9 mm). The majority of transcripts affected by estrous expression in the endometrium belong to the immune system and adhesion molecule family (MX1, MX2, MYL12A, MMP19, CXCL10, IGLL1, and SLPI; P ≤ 0.05), as well as those related with prostaglandin synthesis (OTR and COX-2; P ≤ 0.05). Genes related to apoptosis, P4 synthesis, and prostaglandin receptor were downregulated (CYP11A, BAX, and FPr; P < 0.05) in the CL tissue of cows that expressed Estrus. In addition, four genes were identified as differentially expressed in the 19-day-old conceptus from cows that expressed Estrus (ISG15, PLAU, BMP15, and EEF1A1; P < 0.05). There was also a significant effect of Day 7 concentration of P4 mainly affecting the immune system, adhesion molecules, and wnt signaling pathway of the endometrium (IGLL1, MX2, SLPI, TRD, APC, WNT2, GLYCAM1, and MYL12A; P < 0.05). A significant interaction between estrous expression and P4 concentration on Day 7 was more pronounced in immune system genes (MX1, MX2, TRD, SLPI, and IGLL1; P < 0.05). This study reported that estrous expression at the time of AI favorably altered the gene expression profile in reproductive tissues during the preimplantation phase toward a more receptive state to the elongating conceptus. These effects seem to be more evident in the endometrium during the time of dynamic remodeling for embryo implantation.

  • development of estrous synchronization protocols using melengestrol acetate in bos indicus cattle
    Journal of Animal Science, 2009
    Co-Authors: O Sa G Filho, D.j. Patterson, Jose Luiz Moraes Vasconcelos
    Abstract:

    : Five experiments were conducted on commercial farms in Brazil designed to develop the basis for an Estrus synchronization protocol using melengestrol acetate (MGA) in Bos indicus cattle. These studies resulted in the development of the following protocol: 0.5 mg x d(-1) of MGA between d -14 and -1; 2.0 mg i.m. injection of estradiol cypionate on d -9; 48 h temporary weaning between d 0 and 2; and natural service beginning on d 0. The basis of this protocol was to induce estrous cyclicity before postpartum loss of body condition, prevent premature luteolysis, eliminate the need for labor required to detect Estrus, and consequently increase the likelihood of pregnancy early during the postpartum period. This treatment effectively induced estrous cyclicity among anestrous cows, synchronized Estrus activity, and prevented premature luteolysis with no negative effect on pregnancy.

C. Rajkhowa - One of the best experts on this subject based on the ideXlab platform.

  • development and validation of a new method for visual detection of Estrus in mithun bos frontalis
    Applied Animal Behaviour Science, 2008
    Co-Authors: Mohan Mondal, C. Rajkhowa, M Karunakaran, B S Prakash
    Abstract:

    Abstract The objectives of this study were (1) to develop a suitable scoring scale for Estrus detection based on frequency and reliability of behavioral signs of Estrus in mithun ( Bos frontalis ) and (2) to validate the accuracy of this method for detection of Estrus in primi- and multiparous mithun cows. The study consisted of two experiments. In experiment I, all animals were observed for 30 min at 2 h intervals for at least 35 days, for signs of Estrus. Estrus was further confirmed by rectal examination of the reproductive organs and quantification of plasma progesterone concentrations. Based on the frequency and reliability of a particular sign, a cumulative point scale composed of seven estrous signs that were scored with points, ranging from 3 to 100, was developed. When the sum of the scores exceeded 100 points, the animal was considered to be in Estrus. This was again confirmed by rectal examination of the genitalia and quantification of plasma progesterone concentrations. Calculation of efficiency and accuracy of the developed scale showed that this scale was 100% efficient and accurate, irrespective of parity. In experiment II, the scoring scale was tested for its efficiency and accuracy for detection of Estrus in primi- and multiparous mithun cows based on the behavioral observations recorded twice a day at 0630 and 1630 h for at least 35 days with each observation period lasting for 30 min. Interestingly, efficiency and accuracy of the scale for detection of Estrus was 100% in this experiment. Behavioral Estrus was more intense in primi- than multiparous mithun cows in both experiments. Duration of Estrus was longer in primi- than multiparous animals. The results of the present investigation revealed that no individual behavioral sign of Estrus can be used alone for Estrus detection in mithuns; whereas the efficiency and accuracy of the scoring scale composed of seven estrous signs were 100%, even when animals were observed twice each day. In conclusion, the scoring scale that has been developed was suitable for detection of Estrus in mithuns with high efficiency and accuracy. However, the scale should be validated for use by farmers to assess its practical usefulness.

  • role of lh and prostaglandin f2α on the development and regression of corpus luteum in mithun bos frontalis estrous cycle
    General and Comparative Endocrinology, 2006
    Co-Authors: A Dhali, M Karunakaran, A Mech, Durga Prasad Mishra, C. Rajkhowa
    Abstract:

    The present investigation was designed to study the role of LH and prostaglandin F2alpha (PGF2alpha) on the development and regression of corpus luteum (CL) in the mithun estrous cycle. Blood samples were collected from jugular vein and PGF2alpha secretion was evaluated on the basis of peripheral 15-keto-13,14-dihydro-PGF2alpha (PGFM) concentration. The daily variations in plasma LH, PGFM, and progesterone (P4) concentrations throughout the estrous cycle were monitored in morning and evening blood samples. The variations in plasma LH, PGFM, and P4 concentrations during the early luteal phase were monitored in blood samples that were collected every 2 h until 120 h following the onset of Estrus (Day 0). The pulsatile secretion patterns of plasma LH, PGFM and P4 during Estrus (Day 1), mid-diEstrus (Day 10), and luteolysis (Day 14) were assessed in blood samples that were collected every 15 min for 6h. In the estrous cycle, P4 concentration increased above basal level on day 6-7, peaked on day 10-12 and declined thereafter. Following Estrus, a significant (P<0.01) gradual increase in P4 concentration was observed. LH concentration was found to be significantly (P<0.01) greater around Estrus and it declined gradually (P<0.01) following Estrus. In the estrous cycle, PGFM concentration increased above basal level on day 9-11, peaked on day 16-17, and declined thereafter. The frequency of LH pulses and basal LH concentration were found to be significantly (P<0.01) greater on day 1, but significantly (P<0.01) greater amplitude of LH pulses was found on day 10 and 14. The frequency of P4 and PGFM pulses was found to be significantly (P<0.01) greater on day 1. In contrast, the amplitude of P4 and PGFM pulses and basal P4 and PGFM concentrations were found to be significantly (P<0.01) greater on day 10 and 14. The results indicate that probably the early stages of CL development continued until day 5-6 of the estrous cycle and a fully functional CL existed approximately at the mid estrous cycle. Luteolysis probably started since day 11-13 of the cycle and completed before the onset of the next Estrus. The elevated basal LH concentration along with frequent low amplitude LH pulses were probably required for the early stages of CL development. In contrast, the high amplitude LH pulses of lower frequency during the mid estrous cycle were either sufficient or not required for maintaining the luteal function. Whereas, PGF2alpha pulses of greater amplitude and elevated basal PGF2alpha concentration during the mid and late estrous cycle were probably responsible for luteolysis.

  • behavioral estrous signs can predict the time of ovulation in mithun bos frontalis
    Theriogenology, 2006
    Co-Authors: Mohan Mondal, C. Rajkhowa, B S Prakash
    Abstract:

    Abstract The objective of this study was to investigate the relationship of different behavioral estrous signs and time of ovulation to identify if behavioral estrous sign(s) can be used as predictor of time of ovulation in mithuns. Data were collected for 54 ovulations from 16 mithuns. The animals were monitored for onset of Estrus by observing different behavioral estrous signs at 2 h interval and bull parading thrice a day for 30 min and were further confirmed by plasma progesterone profile. All animals were also observed for any of the estrous signs at every 2 h interval for 30 min and mounting behavior was studied by bull parading at every 2 h for 30 min after onset of Estrus. Time of ovulation was detected by rectal palpation at 2 h interval from onset of Estrus till ovulation. Behavioral signs of Estrus was more intense in primiparous than multiparous mithuns. Ovulation occurred at 26.1 ± 1.1 h (ranging between 20 and 31 h) after the onset of Estrus. As the method used to determine the onset of Estrus is time consuming, labor intensive and no device is yet available to detect onset of Estrus automatically, so this cannot be used practically as a predictor of time of ovulation. The mithun cow at Estrus to be mounted by bull was recorded in all cases (100%). Ovulation occurred 23.5 ± 1.5 h (ranging between 19 and 27 h) after first mounting. Although promising, mounting cannot be assessed automatically, which limits its practical use as a predictor of ovulation. Standing heat was recorded in 98.1% of total Estrus studied in mithun cows and ovulation occurred 21.8 ± 1.3 h (ranging between 19 and 25 h) after first observed standing heat. Standing heat can be detected automatically using mounting detectors. Hence, standing heat can be used practically as ovulation predictor in mithuns. In conclusion, cow to be mounted by mithun bull is the best predictor of ovulation, but non-availability of devices to detect it automatically restricts its practical application. Standing heat that recorded 98.1% Estrus cases in mithun cows, can also be detected automatically using mounting detector, therefore be used widely as an ovulation predictor in field condition for mithun cows.

  • influence of plasma estradiol 17 β and progesterone levels on estrous behaviour in mithun bos frontalis
    Applied Animal Behaviour Science, 2006
    Co-Authors: A Dhali, M Karunakaran, A Mech, Durga Prasad Mishra, C. Rajkhowa
    Abstract:

    Abstract The study was conducted on 10-adult mithun ( Bos frontalis ) cows during the third or fourth postpartum estrous cycle to investigate the influence of plasma estradiol 17-β (E2) and progesterone (P4) levels on the expression of behavioural Estrus. The Estrus was detected in the mithun cows by bull parading and the patterns of behavioural Estrus were recorded. The estrous intensity score (EIS) was assigned according to the visible signs in cows and bull activities. The daily blood samples throughout the estrous cycle were collected by jugular venipuncture and were analysed for E2 and P4 through ELISA. The variations in E2 and P4 concentrations were analysed by repeated measurement ANOVA. The model included the day of estrous cycle and EIS as source of variation. The association of EIS with E2 and P4 was established by the partial correlation analysis. The average estrous cycle length was found 21.3 ± 0.4 days. The average duration ( h ) of Estrus and standing heat were recorded 67.2 ± 7.2 and 10.5 ± 2.7, respectively. The expression of behavioural Estrus was found silent. In the entire estrous cycle, two prominent E2 peaks were observed approximately on day 1 and 17. The peak E2 concentration on day 17 was found significantly ( p p

  • endocrine control of estrous cycle in mithun bos frontalis
    Theriogenology, 2005
    Co-Authors: A Dhali, M Karunakaran, A Mech, Durga Prasad Mishra, C. Rajkhowa
    Abstract:

    Abstract The objective of the present study was to establish the profiles of luteinising hormone (LH), follicle stimulating hormone (FSH), estradiol 17β (E2) and progesterone (P4) secretion and their interrelationships during the natural estrous cycle of mithun ( Bos frontalis ). Daily blood samples were collected from second or third postpartum estrous cycles for determination of plasma concentrations of LH, FSH, E2 and P4. Concentration of P4 was found to be lowest on the day of Estrus. It increased following Estrus, attained the highest concentration on day 11 and decreased thereafter. Concentrations of LH and FSH varied significantly ( p p p  ≤ 0.01) negative relationship between E2 and, LH and FSH was found only during the last 6 days of cycle. The results suggest a negative feedback mechanism on LH and FSH release by E2 and P4 during the respective phases of cycle. A sustained increase in LH and FSH levels during the period before Estrus was probably necessary for the final maturation of ovulatory follicle and subsequent ovulation.

D.j. Patterson - One of the best experts on this subject based on the ideXlab platform.

  • split time artificial insemination in beef cattle i using estrous response to determine the optimal time s at which to administer gnrh in beef heifers and postpartum cows
    Theriogenology, 2016
    Co-Authors: B E Bishop, J M Thomas, J M Abel, S E Poock, Mark R Ellersieck, M F Smith, D.j. Patterson
    Abstract:

    Two experiments evaluated timing of GnRH administration in beef heifers and cows on the basis of estrous status during split-time artificial insemination (AI) after controlled internal drug release (CIDR) based protocols. In experiment 1, Estrus was synchronized for 816 pubertal and prepubertal or peripubertal heifers using the 14-day CIDR-PGF2α (PG) protocol, and in experiment 2, Estrus was synchronized for 622 lactating cows using the 7-day CO-Synch + CIDR protocol. For both experiments, Estrus detection aids (Estrotect) were applied at PG, with Estrus recorded at 66 and 90 hours after PG. Treatments were balanced across locations for heifers using reproductive tract score and weight; whereas for cows, treatments were assigned and balanced to treatment according to age, body condition score, and days postpartum. Timing of AI for heifers and cows was on the basis of Estrus expression 66 hours after PG. Females in each treatment that exhibited Estrus before 66 hours were inseminated at 66 hours, whereas AI was delayed 24 hours until 90 hours after PG for females failing to exhibit Estrus before 66 hours. Females in treatment one received GnRH 66 hours after PG irrespective of Estrus expression; however, in treatment 2, GnRH was administered coincident with delayed AI only to females not detected in Estrus at 66 hours after PG. Among heifers, there was no effect of treatment on overall estrous response (P = 0.49) or AI pregnancy rate (P = 0.54). Pregnancy rate for heifers inseminated at 66 hours was not influenced by GnRH (P = 0.65), and there were no differences between treatments in estrous response during the 24 hours delay period (P = 0.22). Cows in treatment 2 had a greater (P = 0.04) estrous response during the 24-hour delay period resulting in a greater overall estrous response (P = 0.04), but this did not affect AI pregnancy rate at 90 hours (P = 0.51) or total AI pregnancy rate (P = 0.89). Pregnancy rate resulting from AI for cows inseminated at 66 hours was not influenced by GnRH (P = 0.50). In summary, when split-time AI was used with the 14-day CIDR-PG protocol in heifers or the 7-day CO-Synch + CIDR protocol in cows, administration of GnRH at AI to females that exhibited Estrus before 66 hours after PG was not necessary. Furthermore, among heifers for which AI was delayed on the basis of failure to exhibit Estrus before 66 hours after PG, timing of GnRH (66 vs. 90 hours after PG) was more flexible. Delayed administration of GnRH to 90 hours after PG coincident with AI for cows that failed to exhibit Estrus before 66 hours improved overall estrous response; however, in this study, a corresponding increase in pregnancy rate resulting from AI was not observed.

  • delayed insemination of non estrous heifers and cows when using conventional semen in timed artificial insemination
    Journal of Animal Science, 2014
    Co-Authors: J M Thomas, S E Poock, Mark R Ellersieck, M F Smith, D.j. Patterson
    Abstract:

    Two experiments were designed to test the hypothesis that pregnancy rates after fixed-time artificial insemination (FTAI) in beef heifers and cows may be improved by delaying insemination of females that have not expressed Estrus before FTAI. In Exp. 1, Estrus was synchronized for 931 heifers across 3 loca- tions using the 14-d CIDR-PG protocol (controlled internal drug-release (CIDR) insert (1.38 gm proges- terone) on d 0 with removal of CIDR insert on d 14; 25 mg PGF 2α 16 d after CIDR insert removal on d 30; and 100 μg GnRH on d 33, 66 h after PGF 2α ). Estrous detection aids (Estrotect) were applied at PGF 2α on d 30, and estrous expression was recorded at GnRH on d 33. Heifers within each location were randomly assigned to 1 of 2 treatments based on weight and reproductive tract score (RTS): 1) FTAI (concurrent with GnRH, 66 h after PGF 2α ) regardless of estrous expression or 2) FTAI for heifers expressing Estrus and delayed AI (20 h after GnRH) for heifers failing to express Estrus. Heifers assigned to treatment 2 achieved a higher AI pregnancy rate than heifers assigned to treatment 1 (54 versus 46%; P = 0.01). The observed increase in AI pregnancy rate is attributed to the delayed AI of non-estrous heifers in treatment 2, as AI pregnancy rates for non-estrous heif- ers were significantly higher for treatment 2 (49 versus 34%; P = 0.02), while AI pregnancy rates of estrous heifers did not differ by treatment (P = 0.24). In Exp. 2, Estrus was synchronized for 951 mature, suckled cows across 9 locations using the 7-d CO-Synch + CIDR pro- tocol (100 μg GnRH + CIDR insert (1.38 gm progester- one) on d 0; 25 mg PGF 2α at CIDR insert removal on d 7; and 100 μg GnRH on d 10, 66 h after CIDR insert removal). Estrus detection aids (Estrotect) were applied at PGF 2α and CIDR insert removal on d 7, and estrous expression was recorded at GnRH on d 10. Cows within each location were assigned to 1 of 2 treatments based on age, days postpartum, and BCS: 1) FTAI (concur- rent with GnRH, 66 h after PGF 2α ) regardless of estrous expression or 2) FTAI for cows expressing Estrus and delayed AI (20 h after GnRH) for cows failing to express Estrus. No significant effect of treatment was found on AI pregnancy rate (P = 0.76). In summary, FTAI preg- nancy rates in heifers can be improved through a strat- egy of "split-time" AI. However, a statistically signifi- cant increase was not observed in the pregnancy rates of mature suckled cows when using a similar strategy.

  • delayed insemination of nonestrous cows improves pregnancy rates when using sex sorted semen in timed artificial insemination of suckled beef cows
    Journal of Animal Science, 2014
    Co-Authors: J M Thomas, S E Poock, Mark R Ellersieck, M F Smith, S L Lock, D.j. Patterson
    Abstract:

    This experiment was designed to test the hypothesis that delayed insemination of nonestrous cows would increase pregnancy rates when using sex-sorted semen in conjunction with fixed-time artificial insemination (FTAI). Estrus was synchronized for 656 suckled beef cows with the 7-d CO-Synch + controlled internal drug release (CIDR) protocol (100 μg GnRH + CIDR [1.38 g progesterone] on d 0, 25 mg PGF2α at CIDR removal on d 7, and 100 μg GnRH on d 10, 66 h after CIDR removal). Estrus detection aids (Estrotect) were applied at PGF2α and CIDR removal on d 7, and estrous expression was recorded at GnRH on d 10. Cows were assigned to 1 of 3 treatments: 1) FTAI (concurrent with GnRH, 66 h after CIDR removal) with conventional semen regardless of estrous expression, 2) FTAI with sex-sorted semen regardless of estrous expression, or 3) FTAI with sex-sorted semen for cows having expressed Estrus and delayed AI 20 h after final GnRH for cows failing to express Estrus. A treatment × estrous expression interaction was found (P < 0.0001). Higher pregnancy rates (P < 0.0001) were achieved with conventional semen (Treatment 1; 77%) than with sex-sorted semen (Treatments 2 and 3; 51 and 42%, respectively) among cows that expressed Estrus. However, among cows that failed to express Estrus, delayed insemination with sex-sorted semen yielded higher (P < 0.0001) pregnancy rates than with sex-sorted semen at the standard time (Treatments 2 and 3; 3 versus 36%, respectively). Furthermore, among cows that failed to express Estrus, FTAI pregnancy rates when using sex-sorted semen at the delayed time (36%) were comparable (P = 0.9) to those achieved using conventional semen at the standard time (Treatment 1; 37%). These results indicate that delaying AI of nonestrous cows by 20 h from the standard FTAI improves pregnancy rates when sex-sorted semen is used with FTAI.

  • comparison of long term cidr based protocols to synchronize Estrus in beef heifers
    Animal Reproduction Science, 2009
    Co-Authors: N R Leitman, Mark R Ellersieck, M F Smith, D C Busch, D A Mallory, D J Wilson, D.j. Patterson
    Abstract:

    Abstract Two experiments evaluated long-term controlled internal drug release (CIDR) insert-based protocols to synchronize Estrus and compare differences in their potential ability to facilitate fixed-time artificial insemination (FTAI) in beef heifers. In Experiment 1 estrous cycling heifers ( n =85) were assigned to one of two treatments by age and body weight (BW). Heifers with T1 received a CIDR from days 0 to 14, gonadotropin releasing hormone (GnRH) on day 23, and prostaglandin F 2α (PG) on day 30. Heifers with T2 received a CIDR from days 2 to 16, GnRH on day 23, and PG on day 30. Ovaries were evaluated by ultrasonography on days 23 and 25 to determine ovulatory response to GnRH. In Experiment 2 heifers ( n =353) were assigned within reproductive tract scores by age and BW to one of four treatments. Heifers in T1 and T2 received the same treatments described in Experiment 1. Heifers in T3 and T4 received the same treatments as T1 and T2, respectively, minus the addition of GnRH. In Experiments 1 and 2, heifers were fitted with HeatWatch transmitters for estrous detection and AI was performed 12h after Estrus. In Experiment 1 heifers assigned to T1 had larger dominant follicles at GnRH compared to T2 ( P P >0.10). AI conception and final pregnancy rate were similar ( P >0.50). In Experiment 2 estrous response after PG did not differ ( P >0.70). Differences in mean interval to Estrus and variance for interval to Estrus ( P P >0.10). In summary, the greater estrous response following PG and resulting AI conception and final pregnancy rates reported for heifers assigned to the two treatments in Experiment 1 and among the four treatments in Experiment 2 suggest that each of these long-term CIDR-based protocols was effective in synchronizing Estrus in prepubertal and estrous cycling beef heifers. However, the three-way interaction involving treatment length, GnRH, and estrous cyclicity status in Experiment 2 clearly suggests that further evaluation of long-term CIDR-based protocols is required with and without the addition of GnRH and on the basis of estrous cyclicity status to determine the efficacy of these protocols for use in facilitating FTAI.

  • development of estrous synchronization protocols using melengestrol acetate in bos indicus cattle
    Journal of Animal Science, 2009
    Co-Authors: O Sa G Filho, D.j. Patterson, Jose Luiz Moraes Vasconcelos
    Abstract:

    : Five experiments were conducted on commercial farms in Brazil designed to develop the basis for an Estrus synchronization protocol using melengestrol acetate (MGA) in Bos indicus cattle. These studies resulted in the development of the following protocol: 0.5 mg x d(-1) of MGA between d -14 and -1; 2.0 mg i.m. injection of estradiol cypionate on d -9; 48 h temporary weaning between d 0 and 2; and natural service beginning on d 0. The basis of this protocol was to induce estrous cyclicity before postpartum loss of body condition, prevent premature luteolysis, eliminate the need for labor required to detect Estrus, and consequently increase the likelihood of pregnancy early during the postpartum period. This treatment effectively induced estrous cyclicity among anestrous cows, synchronized Estrus activity, and prevented premature luteolysis with no negative effect on pregnancy.

A Dhali - One of the best experts on this subject based on the ideXlab platform.

  • role of lh and prostaglandin f2α on the development and regression of corpus luteum in mithun bos frontalis estrous cycle
    General and Comparative Endocrinology, 2006
    Co-Authors: A Dhali, M Karunakaran, A Mech, Durga Prasad Mishra, C. Rajkhowa
    Abstract:

    The present investigation was designed to study the role of LH and prostaglandin F2alpha (PGF2alpha) on the development and regression of corpus luteum (CL) in the mithun estrous cycle. Blood samples were collected from jugular vein and PGF2alpha secretion was evaluated on the basis of peripheral 15-keto-13,14-dihydro-PGF2alpha (PGFM) concentration. The daily variations in plasma LH, PGFM, and progesterone (P4) concentrations throughout the estrous cycle were monitored in morning and evening blood samples. The variations in plasma LH, PGFM, and P4 concentrations during the early luteal phase were monitored in blood samples that were collected every 2 h until 120 h following the onset of Estrus (Day 0). The pulsatile secretion patterns of plasma LH, PGFM and P4 during Estrus (Day 1), mid-diEstrus (Day 10), and luteolysis (Day 14) were assessed in blood samples that were collected every 15 min for 6h. In the estrous cycle, P4 concentration increased above basal level on day 6-7, peaked on day 10-12 and declined thereafter. Following Estrus, a significant (P<0.01) gradual increase in P4 concentration was observed. LH concentration was found to be significantly (P<0.01) greater around Estrus and it declined gradually (P<0.01) following Estrus. In the estrous cycle, PGFM concentration increased above basal level on day 9-11, peaked on day 16-17, and declined thereafter. The frequency of LH pulses and basal LH concentration were found to be significantly (P<0.01) greater on day 1, but significantly (P<0.01) greater amplitude of LH pulses was found on day 10 and 14. The frequency of P4 and PGFM pulses was found to be significantly (P<0.01) greater on day 1. In contrast, the amplitude of P4 and PGFM pulses and basal P4 and PGFM concentrations were found to be significantly (P<0.01) greater on day 10 and 14. The results indicate that probably the early stages of CL development continued until day 5-6 of the estrous cycle and a fully functional CL existed approximately at the mid estrous cycle. Luteolysis probably started since day 11-13 of the cycle and completed before the onset of the next Estrus. The elevated basal LH concentration along with frequent low amplitude LH pulses were probably required for the early stages of CL development. In contrast, the high amplitude LH pulses of lower frequency during the mid estrous cycle were either sufficient or not required for maintaining the luteal function. Whereas, PGF2alpha pulses of greater amplitude and elevated basal PGF2alpha concentration during the mid and late estrous cycle were probably responsible for luteolysis.

  • influence of plasma estradiol 17 β and progesterone levels on estrous behaviour in mithun bos frontalis
    Applied Animal Behaviour Science, 2006
    Co-Authors: A Dhali, M Karunakaran, A Mech, Durga Prasad Mishra, C. Rajkhowa
    Abstract:

    Abstract The study was conducted on 10-adult mithun ( Bos frontalis ) cows during the third or fourth postpartum estrous cycle to investigate the influence of plasma estradiol 17-β (E2) and progesterone (P4) levels on the expression of behavioural Estrus. The Estrus was detected in the mithun cows by bull parading and the patterns of behavioural Estrus were recorded. The estrous intensity score (EIS) was assigned according to the visible signs in cows and bull activities. The daily blood samples throughout the estrous cycle were collected by jugular venipuncture and were analysed for E2 and P4 through ELISA. The variations in E2 and P4 concentrations were analysed by repeated measurement ANOVA. The model included the day of estrous cycle and EIS as source of variation. The association of EIS with E2 and P4 was established by the partial correlation analysis. The average estrous cycle length was found 21.3 ± 0.4 days. The average duration ( h ) of Estrus and standing heat were recorded 67.2 ± 7.2 and 10.5 ± 2.7, respectively. The expression of behavioural Estrus was found silent. In the entire estrous cycle, two prominent E2 peaks were observed approximately on day 1 and 17. The peak E2 concentration on day 17 was found significantly ( p p

  • endocrine control of estrous cycle in mithun bos frontalis
    Theriogenology, 2005
    Co-Authors: A Dhali, M Karunakaran, A Mech, Durga Prasad Mishra, C. Rajkhowa
    Abstract:

    Abstract The objective of the present study was to establish the profiles of luteinising hormone (LH), follicle stimulating hormone (FSH), estradiol 17β (E2) and progesterone (P4) secretion and their interrelationships during the natural estrous cycle of mithun ( Bos frontalis ). Daily blood samples were collected from second or third postpartum estrous cycles for determination of plasma concentrations of LH, FSH, E2 and P4. Concentration of P4 was found to be lowest on the day of Estrus. It increased following Estrus, attained the highest concentration on day 11 and decreased thereafter. Concentrations of LH and FSH varied significantly ( p p p  ≤ 0.01) negative relationship between E2 and, LH and FSH was found only during the last 6 days of cycle. The results suggest a negative feedback mechanism on LH and FSH release by E2 and P4 during the respective phases of cycle. A sustained increase in LH and FSH levels during the period before Estrus was probably necessary for the final maturation of ovulatory follicle and subsequent ovulation.

M Karunakaran - One of the best experts on this subject based on the ideXlab platform.

  • development and validation of a new method for visual detection of Estrus in mithun bos frontalis
    Applied Animal Behaviour Science, 2008
    Co-Authors: Mohan Mondal, C. Rajkhowa, M Karunakaran, B S Prakash
    Abstract:

    Abstract The objectives of this study were (1) to develop a suitable scoring scale for Estrus detection based on frequency and reliability of behavioral signs of Estrus in mithun ( Bos frontalis ) and (2) to validate the accuracy of this method for detection of Estrus in primi- and multiparous mithun cows. The study consisted of two experiments. In experiment I, all animals were observed for 30 min at 2 h intervals for at least 35 days, for signs of Estrus. Estrus was further confirmed by rectal examination of the reproductive organs and quantification of plasma progesterone concentrations. Based on the frequency and reliability of a particular sign, a cumulative point scale composed of seven estrous signs that were scored with points, ranging from 3 to 100, was developed. When the sum of the scores exceeded 100 points, the animal was considered to be in Estrus. This was again confirmed by rectal examination of the genitalia and quantification of plasma progesterone concentrations. Calculation of efficiency and accuracy of the developed scale showed that this scale was 100% efficient and accurate, irrespective of parity. In experiment II, the scoring scale was tested for its efficiency and accuracy for detection of Estrus in primi- and multiparous mithun cows based on the behavioral observations recorded twice a day at 0630 and 1630 h for at least 35 days with each observation period lasting for 30 min. Interestingly, efficiency and accuracy of the scale for detection of Estrus was 100% in this experiment. Behavioral Estrus was more intense in primi- than multiparous mithun cows in both experiments. Duration of Estrus was longer in primi- than multiparous animals. The results of the present investigation revealed that no individual behavioral sign of Estrus can be used alone for Estrus detection in mithuns; whereas the efficiency and accuracy of the scoring scale composed of seven estrous signs were 100%, even when animals were observed twice each day. In conclusion, the scoring scale that has been developed was suitable for detection of Estrus in mithuns with high efficiency and accuracy. However, the scale should be validated for use by farmers to assess its practical usefulness.

  • role of lh and prostaglandin f2α on the development and regression of corpus luteum in mithun bos frontalis estrous cycle
    General and Comparative Endocrinology, 2006
    Co-Authors: A Dhali, M Karunakaran, A Mech, Durga Prasad Mishra, C. Rajkhowa
    Abstract:

    The present investigation was designed to study the role of LH and prostaglandin F2alpha (PGF2alpha) on the development and regression of corpus luteum (CL) in the mithun estrous cycle. Blood samples were collected from jugular vein and PGF2alpha secretion was evaluated on the basis of peripheral 15-keto-13,14-dihydro-PGF2alpha (PGFM) concentration. The daily variations in plasma LH, PGFM, and progesterone (P4) concentrations throughout the estrous cycle were monitored in morning and evening blood samples. The variations in plasma LH, PGFM, and P4 concentrations during the early luteal phase were monitored in blood samples that were collected every 2 h until 120 h following the onset of Estrus (Day 0). The pulsatile secretion patterns of plasma LH, PGFM and P4 during Estrus (Day 1), mid-diEstrus (Day 10), and luteolysis (Day 14) were assessed in blood samples that were collected every 15 min for 6h. In the estrous cycle, P4 concentration increased above basal level on day 6-7, peaked on day 10-12 and declined thereafter. Following Estrus, a significant (P<0.01) gradual increase in P4 concentration was observed. LH concentration was found to be significantly (P<0.01) greater around Estrus and it declined gradually (P<0.01) following Estrus. In the estrous cycle, PGFM concentration increased above basal level on day 9-11, peaked on day 16-17, and declined thereafter. The frequency of LH pulses and basal LH concentration were found to be significantly (P<0.01) greater on day 1, but significantly (P<0.01) greater amplitude of LH pulses was found on day 10 and 14. The frequency of P4 and PGFM pulses was found to be significantly (P<0.01) greater on day 1. In contrast, the amplitude of P4 and PGFM pulses and basal P4 and PGFM concentrations were found to be significantly (P<0.01) greater on day 10 and 14. The results indicate that probably the early stages of CL development continued until day 5-6 of the estrous cycle and a fully functional CL existed approximately at the mid estrous cycle. Luteolysis probably started since day 11-13 of the cycle and completed before the onset of the next Estrus. The elevated basal LH concentration along with frequent low amplitude LH pulses were probably required for the early stages of CL development. In contrast, the high amplitude LH pulses of lower frequency during the mid estrous cycle were either sufficient or not required for maintaining the luteal function. Whereas, PGF2alpha pulses of greater amplitude and elevated basal PGF2alpha concentration during the mid and late estrous cycle were probably responsible for luteolysis.

  • influence of plasma estradiol 17 β and progesterone levels on estrous behaviour in mithun bos frontalis
    Applied Animal Behaviour Science, 2006
    Co-Authors: A Dhali, M Karunakaran, A Mech, Durga Prasad Mishra, C. Rajkhowa
    Abstract:

    Abstract The study was conducted on 10-adult mithun ( Bos frontalis ) cows during the third or fourth postpartum estrous cycle to investigate the influence of plasma estradiol 17-β (E2) and progesterone (P4) levels on the expression of behavioural Estrus. The Estrus was detected in the mithun cows by bull parading and the patterns of behavioural Estrus were recorded. The estrous intensity score (EIS) was assigned according to the visible signs in cows and bull activities. The daily blood samples throughout the estrous cycle were collected by jugular venipuncture and were analysed for E2 and P4 through ELISA. The variations in E2 and P4 concentrations were analysed by repeated measurement ANOVA. The model included the day of estrous cycle and EIS as source of variation. The association of EIS with E2 and P4 was established by the partial correlation analysis. The average estrous cycle length was found 21.3 ± 0.4 days. The average duration ( h ) of Estrus and standing heat were recorded 67.2 ± 7.2 and 10.5 ± 2.7, respectively. The expression of behavioural Estrus was found silent. In the entire estrous cycle, two prominent E2 peaks were observed approximately on day 1 and 17. The peak E2 concentration on day 17 was found significantly ( p p

  • endocrine control of estrous cycle in mithun bos frontalis
    Theriogenology, 2005
    Co-Authors: A Dhali, M Karunakaran, A Mech, Durga Prasad Mishra, C. Rajkhowa
    Abstract:

    Abstract The objective of the present study was to establish the profiles of luteinising hormone (LH), follicle stimulating hormone (FSH), estradiol 17β (E2) and progesterone (P4) secretion and their interrelationships during the natural estrous cycle of mithun ( Bos frontalis ). Daily blood samples were collected from second or third postpartum estrous cycles for determination of plasma concentrations of LH, FSH, E2 and P4. Concentration of P4 was found to be lowest on the day of Estrus. It increased following Estrus, attained the highest concentration on day 11 and decreased thereafter. Concentrations of LH and FSH varied significantly ( p p p  ≤ 0.01) negative relationship between E2 and, LH and FSH was found only during the last 6 days of cycle. The results suggest a negative feedback mechanism on LH and FSH release by E2 and P4 during the respective phases of cycle. A sustained increase in LH and FSH levels during the period before Estrus was probably necessary for the final maturation of ovulatory follicle and subsequent ovulation.