Melengestrol acetate, estradiol-17β and GnRH for synchronization of estrus and ovulation in beef cows

1999 ◽  
Vol 79 (1) ◽  
pp. 39-43 ◽  
Author(s):  
J. Thundathil ◽  
J. P. Kastelic ◽  
W. O. Olson ◽  
R. B. Cook ◽  
R. J. Mapletoft
Keyword(s):  
Key Words ◽  
Pregnancy Rate ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Conception Rate ◽  
Estrus Synchronization ◽  
Short Term ◽  
Melengestrol Acetate ◽  
Conception Rates ◽  
Estradiol 17Β

Three experiments were conducted with suckled crossbred beef cows to determine the efficacy of various short-term regimens for synchronizing estrus or ovulation and to determine whether feeding melengestrol acetate (MGA) after timed AI will increase pregnancy rate. In exp. 1, all cows (n = 141) were given 0.5 mg MGA head−1 d−1 for 7 d (days 1 to 7), 1 or 5 mg E17β (and 100 mg progesterone) or 100 µg GnRH on day 1, and 500 µg cloprostenol on day 7. There were no significant differences among groups for estrous or synchronized conception rates (average, 84.4 and 52.1%, respectively). With an identical protocol in exp. 2 (78 cows), by day 11, cows given 5 mg E17β had the highest estrous and synchronized pregnancy rates (65.4 and 42.3%), compared to 1 mg E17β (46.2 and 15.4%) and GnRH (34.6 and 11.5%). Cows not detected in estrus were timed-inseminated and given 100 µg GnRH, 100 h after cloprostenol. There were no significant differences among groups for synchronized conception rate to timed AI (65.0%) or synchronized pregnancy rate to all inseminations (56.4%). Overall, 5 mg E17β gave the most consistent results. In exp. 3, 84 cows were given 100 µg GnRH on days 1 and 9, 500 µg cloprostenol on day 7, and were timed-inseminated on day 10. Half were fed MGA (0.5 mg head−1 d−1) on days 16 to 22, but the pregnancy rate was not different from that in the remaining cows (55.0 versus 47.8%, P > 0.5). Key words: Ovary, follicles, estrus synchronization, beef cows

Melengestrol acetate and estradiol-17β for synchronizing estrus and improving reproductive performance in beef cattle

1997 ◽  
Vol 77 (4) ◽  
pp. 683-688 ◽  
Author(s):  
J. P. Kastelic ◽  
D. H. McCartney ◽  
W. O. Olson ◽  
A. D. Barth ◽  
R. J. Mapletoft
Keyword(s):  
Beef Cattle ◽  
Key Words ◽  
Pregnancy Rate ◽  
Reproductive Performance ◽  
Pregnancy Rates ◽  
Melengestrol Acetate ◽  
Estradiol 17Β

Four experiments were conducted to investigate the use of melengesterol acetate (MGA) and estradiol-17β (E-17β) for synchronizing estrus and improving reproductive performance in beef cattle. Synchronized pregnancy rates were higher (P < 0.05) in heifers fed MGA after AI than controls (4 of 9 versus 0 of 7, respectively), but were not different for cows (20 of 37, 54% versus 23 of 40, 58%). Estrus rate (percentage of cows detected in estrus) was higher (P < 0.05) for cows treated with E-17β + MGA compared with those treated with cloprostenol alone (85.0 versus 65.9%). Synchronized pregnancy rates were not significantly affected by feeding MGA or grain only after detected estrus and AI (20 of 31, 64% versus 17 of 30, 57%). For 20 cows not detected in estrus and bred 100 h after cloprostenol treatment, pregnancy rate was higher (P < 0.05) for those fed MGA after AI than controls (6 of 11, 54% versus 1 of 9, 11%). Feeding MGA after breeding may help to improve pregnancy rates. Key words: Melengesterol acetate, estradiol-17β, estrus, reproductive performance, beef cattle

scholarly journals Effect of different protocols for estrus synchronization on reproductive performance of Santa Inês ewes under Amazon environmental conditions

2020 ◽  
Vol 43 ◽  
pp. e48954
Author(s):  
Regina Oliveira da Silva ◽  
Roseane Pinto Martins de Oliveira ◽  
André Ferreira Silva ◽  
Franklyn Ferreira de Oliveira ◽  
João Paulo Ferreira Rufino ◽  
...  
Keyword(s):  
Experimental Design ◽  
Pregnancy Rate ◽  
Reproductive Performance ◽  
Environmental Conditions ◽  
Pregnancy Rates ◽  
Estrus Synchronization ◽  
Test Results ◽  
Short Term ◽  
Santa Inês

 The objective of this study was to evaluate the effect of different hormonal protocols on the reproductive performance of Santa Inês ewes in Amazon environmental conditions. Twenty-two Santa Inês ewes between 3 and 4 years-old were distributed in a randomized block experimental design, where the treatments consisted of two protocols for estrus synchronization (short and long) with eleven animals each. Data on the occurrence of estrus were described for each protocol. Data of estrus, pregnancy, and prolificity were firstly subjected to ANOVA and a subsequent Tukey’s test. Results were considered significant at p ≤ 0.05. The short-term protocol presented an interesting successful rate, where above 70% ewes tested had estrus. The long-term protocol also achieved a high successful rate, where above 80% ewes tested had estrus. However, comparing the protocols, the long-term protocol presented better results of positive estrus and pregnancy rates in ewes. Thus, it can be concluded that both protocols presented satisfactory results regarding estrus manifestation, and prolificity (lambs produced per ewe). However, under Amazon environmental conditions, the long-term protocol presented better results regarding positive manifestation of estrus and pregnancy rate.

scholarly journals The effect of clitoral stimulation post artificial insemination on pregnancy rates of multiparous Bos indicus beef cows submitted to estradiol/progesterone-based estrus synchronization protocol

2020 ◽  
Vol 98 (7) ◽  
Author(s):  
Ramiro V Oliveira Filho ◽  
Reinaldo F Cooke ◽  
Gustavo A de Mello ◽  
Victor M Pereira ◽  
Jose Luiz M Vasconcelos ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Artificial Insemination ◽  
Body Condition Score ◽  
Bos Indicus ◽  
Fixed Time ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Estrus Synchronization ◽  
Exit Velocity ◽  
Clitoral Stimulation

Abstract Clitoral stimulation after artificial insemination (AI) in beef cattle is a common practice utilized by AI technicians; however, the effect of clitoral stimulation during fixed-time AI (TAI) is still unknown. The objective of the present experiment was to evaluate the effect of clitoral stimulation on temperament responses and pregnancy rates to TAI in Bos indicus beef cows. A total of 1,186 multiparous Nellore cows across three different locations were assigned to an estradiol/progesterone-based estrus synchronization + TAI protocol (day −11 to 0). Cows were randomly assigned to receive either 3 s of clitoral stimulation (n = 602) or no clitoral stimulation (n = 584) immediately after TAI (day 0). Cow body condition score (BCS) was recorded on day −11. Estrus expression was evaluated based on estrus detection visual aid patch activation on day 0 (estrus, ≥50% activated; no estrus, &lt;50% activated). Temperament was assessed by individual chute score based on a 5-point scale before TAI, and individual exit velocity was measured after clitoral stimulation. Pregnancy diagnosis was performed 30 d after TAI via transrectal ultrasonography. Pregnancy rate to TAI was positively affected by BCS (P &lt; 0.01) and estrus expression (P = 0.03). Pregnancy rates of cows receiving clitoral stimulation did not differ (P = 0.39) from cows non-stimulated (47.5 ± 4.6% vs. 44.3 ± 4.6%, respectively). No interaction of clitoral stimulation and estrus expression was observed (P = 0.26). Chute score was positively correlated to exit velocity (P &lt; 0.01; r = 0.29); however, clitoral stimulation did not affect exit velocity (P = 0.86). In summary, pregnancy rates to TAI are influenced by various factors and multiple strategies have the potential to increase the fertility of beef cows submitted to TAI; however, clitoral stimulation of Bos indicus beef cows did not improve TAI pregnancy rate.

scholarly journals 27 A retrospective analysis of bull:cow ratio effects on pregnancy rates of beef cows previously enrolled in fixed-time artificial insemination protocols

2019 ◽  
Vol 97 (Supplement_1) ◽  
pp. 20-20
Author(s):  
Claire L Timlin ◽  
Laura Hungerford ◽  
Tracey Redifer ◽  
John F Currin ◽  
Vitor R G Mercadante
Keyword(s):  
Pregnancy Rate ◽  
Artificial Insemination ◽  
Fixed Time ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Economic Feasibility ◽  
Average Ratio ◽  
Conception Rates ◽  
Virginia Department ◽  
Natural Service

Abstract This retrospective study analyzed the effect of bull:cow ratio on pregnancy rates of cows returning to estrus after enrollment in fixed-time artificial insemination (TAI). Data were compiled over the course of 6 breeding seasons between 2014 and 2017 from the Virginia Department of Corrections herd containing 15 farms and 141 groups of cows (average 44 cows/group). Multiparous cows aged 2 years and older (n = 6002) were exposed to estrus synchronization. Non-pregnant cows after TAI (n=3079, average 21 cows/group) were exposed to natural service with bulls diagnosed as fertile by a breeding soundness exam. Percent data were given an arcsine transformation. A one-way ANOVA evaluated TAI rates by season and a linear regression was performed to compare conception rates to the bull:cow ratio. Pregnancy rate to TAI among groups averaged 53% and ranged from 11% to 83%. First bull pregnancy rate of cows returning to estrus was 47% overall, with fall seasons having greater conception rates than spring (51.1% vs. 44.5%, P = 0.03). The ratio of bulls to total number of cows ranged from 1:8 to 1:68 with an average ratio of 1:28. The ratio of bulls to the number of open cows ranged from 1:2 to 1:39 with an average ratio of 1:14. There was no correlation between the bull:cow ratio and return to estrus pregnancy rate (r = -0.12), and there was no correlation between the number of open cows per bull and return to estrus conception rates (r = -0.17). Thus, higher bull:cow ratios (between 1:8 and 1:68) did not effect return to estrus pregnancy rate; producers may consider a lower number of bulls needed for natural service breeding post TAI, decreasing bull related costs and increasing the economic feasibility of adopting TAI protocols.

Selection for fertility traits in Brahmans increases heifer pregnancy rates from yearling mating

2010 ◽  
Vol 50 (6) ◽  
pp. 345 ◽  
Author(s):  
T. J. Schatz ◽  
G. A. Jayawardhana ◽  
R. Golding ◽  
M. N. Hearnden
Keyword(s):  
Pregnancy Rate ◽  
Pregnancy Rates ◽  
Conception Rate ◽  
First Year ◽  
Weight Range ◽  
The Third ◽  
Conception Rates ◽  
Second Year ◽  
Selection For ◽  
Fertility Traits

The performance of heifers from a Brahman herd that was selected for fertility was compared with Brahman heifers sourced from commercial properties using three year-groups of heifers. Each year, conception rates from yearling mating were significantly higher in heifers from the selected herd (SEL) than in heifers sourced from commercial properties (COM), despite the average joining weight of the SEL heifers being lower each year. The pregnancy rate in SEL heifers was 24% higher (P = 0.008) in the first year, 36% higher (P = 0.005) in the second year and 45% higher (P < 0.001) in the third year. Over the 3 years of the study, the conception rate was 35% higher (P = 0.009) in SEL heifers than in COM heifers. Joining weight also affected pregnancy rates. When heifers were split into weight ranges according to their pre-joining weight, pregnancy rates were significantly higher (P = 0.018) in the heavier weight range than the lighter one. The results indicate that selection for fertility has been successful in improving conception rates from yearling mating in SEL heifers.

scholarly journals PSXIII-19 Effects of injectable trace mineral supplements at the initiation of estrus synchronization on pregnancy rates in beef cows

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 371-372
Author(s):  
Carl Dahlen ◽  
Kacie L McCarthy ◽  
Sarah Underdahl ◽  
Mellissa Crosswhite ◽  
Bryan Neville
Keyword(s):  
Pregnancy Rate ◽  
Body Condition Score ◽  
Transrectal Ultrasound ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Estrus Synchronization ◽  
Negative Effects ◽  
Trace Mineral ◽  
Mineral Supplements ◽  
Red Angus

Abstract The objective of this experiment was to evaluate effects of administering injectable trace mineral supplements to beef cows at the initiation of estrus synchronization on pregnancy rates to AI. Four hundred seventeen Angus and Red Angus-based beef cows at two locations were stratified by parity, body condition score, and days postpartum, then randomly assigned to one of 2 treatments; 1) untreated controls (CON; n = 208); or 2) received 90 mg Cu, 60 mg Mn, 30 mg Se, and 360 mg Zn as an injectable TM supplement initiation of synchronization (6 ml Multimin 90 s.q.; ITM; n = 209). All cows received a controlled internal drug release insert (CIDR; 1.38g progesterone) and 100 µg gonadotropin-releasing hormone (GnRH) im, followed in 7 d by CIDR removal and 25 mg prostaglandin F2alpha, followed in 60 to 66 hours with AI and 100 µg GnRH i.m. Cows received an Estrotech heat detection patch on their tailhead at CIDR removal, which was assigned an activation status at AI (yes = ≥50% of patch activated; no = &lt; 50%). Pregnancy status was determined via transrectal ultrasound on day 35 to 40 after AI to determine pregnancy rates to AI in response to treatments. No location × treatment interaction was present (P = 0.66), but pregnancy rate was greater (P &lt; 0.01) for Location 1 (76.9%; 70 of 91) than for Location 2 (58.0%; 189 of 326). However, no differences (P = 0.50) in pregnancy rates were observed among CON (123/208; 63.5%) and ITM (127/209; 60.8%). Overall, 56.6% of cows had activated estrus detection patches at AI, and more cows with activated patches became pregnant (169/236; 71.6%) compared with cows having unactivated patches (90/181; 49.7%). In this experiment, ITM administration at the initiation of estrus synchronization had no negative effects on pregnancy rate to AI.

scholarly journals 58 A retrospective analysis of bull:cow ratio effects on pregnancy rates of beef cows previously enrolled in fixed-time artificial insemination protocols

2019 ◽  
Vol 97 (Supplement_1) ◽  
pp. 1-1
Author(s):  
Claire L Timlin ◽  
Laura Hungerford ◽  
Tracey Redifer ◽  
John F Currin ◽  
Vitor R G Mercadante
Keyword(s):  
Pregnancy Rate ◽  
Artificial Insemination ◽  
Fixed Time ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Economic Feasibility ◽  
Average Ratio ◽  
Conception Rates ◽  
Virginia Department ◽  
Natural Service

Abstract This retrospective study analyzed the effect of bull:cow ratio on pregnancy rates of cows returning to estrus after enrollment in fixed-time artificial insemination (TAI). Data were compiled over the course of 6 breeding seasons between 2014 and 2017 from the Virginia Department of Corrections herd containing 15 farms and 141 groups of cows (average 44 cows/group). Multiparous cows aged 2 years and older (n = 6002) were exposed to estrus synchronization. Non-pregnant cows after TAI (n = 3079, average 21 cows/group) were exposed to natural service with bulls diagnosed as fertile by a breeding soundness exam. Percent data were given an arcsine transformation. A one-way ANOVA evaluated TAI rates by season and a linear regression was performed to compare conception rates to the bull:cow ratio. Pregnancy rate to TAI among groups averaged 53% and ranged from 11% to 83%. First bull pregnancy rate of cows returning to estrus was 47% overall, with fall seasons having greater conception rates than spring (51.1% vs. 44.5%, P = 0.03). The ratio of bulls to total number of cows ranged from 1:8 to 1:68 with an average ratio of 1:28. The ratio of bulls to the number of open cows ranged from 1:2 to 1:39 with an average ratio of 1:14. There was no correlation between the bull:cow ratio and return to estrus pregnancy rate (r = -0.12), and there was no correlation between the number of open cows per bull and return to estrus conception rates (r = -0.17). Thus, higher bull:cow ratios (between 1:8 and 1:68) did not effect return to estrus pregnancy rate; producers may consider a lower number of bulls needed for natural service breeding post TAI, decreasing bull related costs and increasing the economic feasibility of adopting TAI protocols

scholarly journals 142 Evaluation of estrus detection patches as a tool to classify postpartum beef cows as estrous cycling or anestrous prior to the start of the breeding season

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 116-117
Author(s):  
Emily G Smith ◽  
Rachael C Bonacker ◽  
Carson M Andersen ◽  
Jordan M Thomas
Keyword(s):  
Pregnancy Rate ◽  
Breeding Season ◽  
Beef Cows ◽  
Estrus Synchronization ◽  
Serum Progesterone ◽  
Estrus Detection ◽  
Estrous Cyclicity ◽  
Type Ii Errors ◽  
Estrous Cycling

Abstract Estrus detection patches were evaluated as a tool to classify postpartum cows as estrous cycling or anestrous at the start of the breeding season. EstrotectTM Breeding Indicators were applied to 257 postpartum beef cows in three locations 25 days prior to the start of estrus synchronization. Coincident with the start of estrus synchronization, patches were scored using a 1 to 4 scale (1 = 0–25%; 2 = 25–50%; 3 = 50–75%; 4 = 75–100%) with scores of 3 or 4 considered activated. Blood samples were collected from each cow 10 days prior to, and at the start of the estrus synchronization. Serum progesterone concentrations were determined via radioimmunoassay; cows were considered estrous cycling if one or both samples exceeded a concentration of 0.5 ng/ml. Based on progesterone, 54.9% of cows were estrous cycling at the start of estrus synchronization. When missing patches were considered inconclusive results, use of patches to infer estrous cyclicity resulted in 85.0% sensitivity and 79.2% specificity with a positive predictive value of 87.2%. However, 75.1% of all cows presented with missing patches at the start of synchronization. If missing patches were considered activated, sensitivity was 95.7%, but specificity (16.4%) and PPV (58.2%) were poor, as 47.6% of cows presenting with missing patches were anestrous based on progesterone. Across all cows, pregnancy rate to AI was 58.0% (149/257). Cows with activated patches that were classified as false positives based on serum progesterone concentrations achieved a 71.4% (5/7) pregnancy rate to AI, raising questions as to whether sensitivity was underestimated due to inherent Type II errors in classification of cyclicity via progesterone. In summary, estrus detection aids are a sensitive tool to identify estrous cycling postpartum cows prior to the start of the breeding season; however, poor specificity and patch retention are limitations for this application.

scholarly journals Calving sub-season and reproductive efficiency of beef cows

2010 ◽  
Vol 39 (10) ◽  
pp. 2182-2186
Author(s):  
Cristiane Reinher ◽  
Júlio Otávio Jardim Barcellos ◽  
Vanessa Peripolli ◽  
Ênio Rosa Prates ◽  
Maria Eugênia Andrighetto Canozzi
Keyword(s):  
Pregnancy Rate ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Reproductive Efficiency ◽  
Climate Variations ◽  
Southern Brazil ◽  
Chi Square ◽  
Chi Square Test

It was evaluated in this work the effect of calving sub-season on the pregnancy rate of 7,726 multiparous Hereford beef cows grazing on natural pastures in southern Brazil, from 1994 to 2007. Calving sub-season periods were divided in 20-day intervals from August 12th to 31st; from September 1st to 20th; from September 21st to October 10th; from October 11th to 31st; from November 1st to 20th. Calving in each sub-season and pregnancy rate (PR) were analyzed by the Chi-square test. Overall means of each sub-season were 92.7% (from August 12th to 31st), 90.6% (from September 1st to 20th), 82.1% (from September 21st to October 10th), 77.7% (from October 11th to 31st), and 70.6% (from November 1st to 20th). Calving sub-season significantly influenced pregnancy rate. Cows which calved in the initial sub-season showed higher pregnancy rates than cows which calved from the fourth calving sub-season. However this difference did not occur in 1999 and in 2007 since calving rates did not statistically differ among the five sub-seasons. In 1998 and 2004, calving rates were lower and the effects of calving sub-season on pregnancy rates were higher, possibly due to climate variations. In general, pregnancy rate decreases as calving occurs later in the year, particularly in years when the weather adversely affects pasture growth.

scholarly journals The influence of adding estradiol to semen on reproductive performance of sows

1991 ◽  
Vol 71 (2) ◽  
pp. 589-591 ◽  
Author(s):  
R. N. Kirkwood ◽  
P. A. Thacker
Keyword(s):  
Key Words ◽  
Litter Size ◽  
Reproductive Performance ◽  
Artificial Insemination ◽  
Pregnancy Rates ◽  
And Control ◽  
Estradiol 17Β

One hundred gilts and one hundred mixed-parity sows of Yorkshire and Landrace breeding were inseminated with semen with or without an additional 10 μg estradiol-17β. Pregnancy rates of gilts receiving estradiol-supplemented and control semen were 90 and 79%, respectively (P < 0.09). The estradiol supplementation of semen did not improve the pregnancy rates or litter size in sows. Key words: Swine, artificial insemination, estradiol

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