scholarly journals 42 Effect of injectable trace mineral supplementation on beef cows fertility and overall mineral status

2020 ◽  
Vol 98 (Supplement_2) ◽  
pp. 45-45
Author(s):  
Stefania Pancini ◽  
Jhon F Currin ◽  
Jamie L Stewart ◽  
Sherrie Clark ◽  
Tracey Redifer ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Post Partum ◽  
Fixed Time ◽  
Beef Cows ◽  
Negative Control ◽  
Trace Mineral ◽  
Mineral Status ◽  
Mineral Supplementation ◽  
Estrus Detection ◽  
Natural Service

Abstract The objective of this study was to evaluate the effect of an injectable multi-mineral complex supplementation on beef cows overall mineral status and fertility. This study involved 9 different locations in the state of Virginia and a total of 1,128 Angus crossbred multiparous cows. All cows had ad libitum access to forage and water, and received mineral supplementation in form of mineral blocks. All cows were enrolled in a 7-d CO-Synch + CIDR fixed-time AI (FTAI) protocol, followed by natural service for an approximately 70-d breeding season. At the initiation of the FTAI protocol (d 0) cows were stratified by days post-partum (82 ± 18 d) and randomly assigned to one of two treatments: 1) One dose of an injectable trace mineral containing zinc (60mg/ml), copper (15mg/ml), selenium (5mg/ml) and manganese (10mg/ml) on d 0 (n = 560; 1 ml/90 kg BW of Multimin® 90, Multimin USA, Ft. Collins, CO); or 2) a negative control with no trace mineral injection (n = 568). BCS was recorded at d 0, 61 and 121. Estrus detection was recorded at d 10 using an estrus detection patch. Pregnancy was diagnosed on days 71 and 131 by ultrasonography. Liver biopsies were collected on days 0 and 45 in a subgroup of 140 cows from both treatments and distributed among all locations. No differences between treatments were detected in days post-partum (P = 0.83), BCS (P ≥ 0.42) and estrus detection (P= 0.12), neither in mineral status of copper, manganese, selenium or zinc (P ≥ 0.28). No effect of treatment was detected (P ≥ 0.20) in AI pregnancy rate (57%) or overall pregnancy rate (93%). In conclusion, one dose of injectable trace mineral administrated 10 days before AI did not improve pregnancy rate or overall mineral status in multiparous beef cows enrolled in FTAI.

scholarly journals 156 Injectable trace mineral supplementation on grazing beef cows: effect on overall mineral status and fertility

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 117-117
Author(s):  
Stefania Pancini ◽  
John Currin ◽  
Jamie L Stewart ◽  
Sherrie Clark ◽  
Tracey Redifer ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Body Condition Score ◽  
Post Partum ◽  
Fixed Time ◽  
Beef Cows ◽  
Negative Control ◽  
Trace Mineral ◽  
Mineral Status ◽  
Beef Cow ◽  
Estrus Detection

Abstract The objective of this study was to evaluate the effect of two doses of an injectable multi-mineral complex supplementation on beef cow fertility and overall mineral status. A total of 986 Angus crossbred multiparous cows at 8 locations in Virginia were enrolled in a 7-day CO-Synch+CIDR fixed-time artificial insemination (FTAI) protocol, followed by natural service for an approximately 70 d breeding season. All cows had ad libitum access to water, mineral blocks, and diet composed of hay, grass, sudangrass, sorghum grain and commodity pellets, depending on location. Approximately 30 days before calving (d -120, day of AI is d 0) cows were randomly assigned to one of two treatments: 1) Two doses (6 mL) of Multimin® 90 (Multimin USA, Ft. Collins, CO) at d -120 and d -10 (MIN; n = 494); or 2) a negative control with no trace mineral injection (CTRL; n = 492). Body condition score was recorded on d -10, 60 and 120. Estrus detection was recorded at d 0 using estrus detection patches. Pregnancy was diagnosed on d 60 and 120 by ultrasonography. Liver biopsies were collected on d -10 and 60 in a subgroup of 60 cows equally distributed between treatments and among all locations. No differences between treatments were detected in days post-partum (P = 0.66), BCS (P = 0.24) and estrus expression (P = 0.11). Mineral status of copper, manganese, selenium or zinc was similar between treatments before (P = 0.20) and after treatment (P = 0.17). No effect of treatment was detected in FTAI pregnancy rate (50.8%, P = 0.52) or overall pregnancy rate (89.6%, P = 0.64). Two doses of injectable trace mineral administrated approximately 30 days before calving and 10 days before FTAI did not improve pregnancy rate or overall mineral status in multiparous beef cows in Virginia.

scholarly journals 202 Repeatability of estrus detection patch readings and relationship with breeding success

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 30-31
Author(s):  
Vitor R G Mercadante ◽  
Robin R White ◽  
Heather L Bradford ◽  
Nicholas W Dias ◽  
Claire Timlin ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Breeding Season ◽  
False Negative ◽  
Fixed Time ◽  
True Negative ◽  
Full Dataset ◽  
Activated State ◽  
Estrus Detection ◽  
Virginia Department ◽  
Natural Service

Abstract The objective of this study was to assess how well estrus detection patch readings correlated to successful AI breedings and to characterize the within-cow repeatability of estrus detection patch readings across breeding seasons. Data from the Virginia Department of Corrections beef cattle herds were collated for 7 locations over 7 years, with 2 calving seasons per year. Data from Spring of 2011 were missing. The full dataset contained 19,253 individual animal observations, of which 2,389 observations were omitted for failure to report estrus detection patch data. The relationship between estrus patch reading and pregnancy rate to fixed-time AI and subsequent natural service pregnancy rate was assessed by calculating the sensitivity and specificity of patch readings within each location during each breeding season. A true positive was defined as a patch activating and a cow being confirmed pregnant. A true negative was a patch remaining in the non activated state and a cow being confirmed open. A false positive was defined as a patch activating and a cow being confirmed open. A false negative was a patch failing to activate and a cow being confirmed pregnant. Pregnancy rate to AI sensitivity ranged from 0.2 to 1 with a mean of 0.583. Specificity ranged from 0 to 1 with a mean of 0.525. Subsequent natural service pregnancy rate), ranges in sensitivity (0.197 to 1.00, mean 0.563) and specificity (0 to 1, mean 0.545) were similar. Of the 6,249 animals with usable patch data, 934 never presented with an activated patch and 2,064 presented with an activated patch every breeding season. The remaining 3,251 animals averaged presenting with an activated patch 47% of the time and a non-activated patch 46% of the time. Odds of getting pregnant by AI for cows that always flag with the heat patch were 0.415.

PSV-1 Injectable trace mineral supplementation on grazing beef cows: Effect on subsequent offspring birth weight and weaning weight

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 309-309
Author(s):  
Stefania Pancini ◽  
John Currin ◽  
Jamie L Stewart ◽  
Sherrie Clark ◽  
Tracey Redifer ◽  
...  
Keyword(s):  
Birth Weight ◽  
Beef Cows ◽  
Negative Control ◽  
Late Gestation ◽  
Early Lactation ◽  
Trace Mineral ◽  
Weaning Weight ◽  
Mineral Supplementation ◽  
Ad Libitum ◽  
Additional Mineral

Abstract This study evaluated the effect of an injectable multi-mineral complex supplementation on grazing beef cows on subsequent offspring birth weight (BW) and adjusted weaning weight (AWW). Experiment 1 included 1,128 Angus crossbred multiparous suckled cows, from 9 locations in Virginia, that were randomly assigned to one of two treatments: 1) One dose of an injectable trace mineral (6 mL; Multimin® 90, Multimin USA, Ft. Collins, CO) at 71.4±16.8 d of lactation (n = 560); or 2) a negative control with no trace mineral injection (n = 568). In experiment 2, 986 Angus crossbred multiparous suckled cows, at 7 locations in Virginia, were randomly assigned to one of two treatments: 1) Two doses of an injectable trace mineral (6 mL; Multimin® 90) at 118.3±17 days before calving and at 67.7±17.4 d of lactation (n = 494); or 2) negative control with no trace mineral injection (n = 492). All cows had ad libitum access to forage and water, and received additional mineral supplementation in form of mineral blocks. Calves were weaned at approximately 7 months of age, and 205-day AWW was calculated based on birth day, age of weaning and age of dam. No differences between treatments were detected for BW (33.7±1.01 kg; P = 0.50) and AWW (212.2±5.0 kg; P = 0.25) when only one dose of injectable trace mineral was administered to the dam at early lactation. Similarly, when two doses of injectable trace mineral were administrated BW (35.6±1.1 kg; P = 0.70) and AWW (259.4±6.1 kg; P = 0.83) did not differ between treatments. In conclusion, one or two doses of injectable trace mineral administrated at late gestation and/or during lactation had no effect on offspring BW and AWW.

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.

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

2021 ◽  
Author(s):  
Claire L Timlin ◽  
Nicholas W Dias ◽  
Laura Hungerford ◽  
Tracey Redifer ◽  
John F Currin ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Artificial Insemination ◽  
Fixed Time ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Economic Feasibility ◽  
Virginia Department ◽  
Breeding Soundness ◽  
Breeding Seasons ◽  
Natural Service

Abstract This retrospective study aimed to determine if the number of cows exposed per bull affects pregnancy rates of cows returning to estrus after fixed-time artificial insemination (FTAI). Data were compiled over the course of 13 breeding seasons (6 fall and 7 spring seasons) between 2010 and 2017 from the Virginia Department of Corrections herd. Available records contained data from 17 farms and 324 groups of cows (average 47 cows/group). Multiparous cows and heifers (average age per group: 5.11 ± 0.14 years; n = 14,868) were exposed to FTAI. After FTAI, animals were placed on pasture with bulls diagnosed as fertile by a breeding soundness exam for natural service of cows who did not become pregnant to FTAI (n = 7,248; average 22 cows/group). Animals were classified as pregnant to FTAI, to natural service on first return to estrus, or to natural service on second or subsequent estrus determined by fetal aging at pregnancy diagnosis. The bull:cow ratio for the total number of cows exposed ranged from 1:9 to 1:73 with an average of 1:31. The bull:cow ratio considering only open cows exposed after FTAI ranged from 1:2 to 1:44 with an average of 1:14. There was significant negative, small correlation between the bull:cow ratio for total number of cows exposed and return to estrus pregnancy rate in fall breeding seasons (P = 0.01, r 2 = 0.04) but not in spring (P = 0.90). There was a significant negative, small correlation between bull:cow ratio of open cows exposed and pregnancy rates to first return to estrus in fall herds with a single sire (P < 0.001, r 2 = 0.11). There was no correlation in fall herds using multiple sires or spring herds (P ≥ 0.12). Bull:cow ratio accounted for only 1 – 11% of variation in the pregnancy rates, thus we conclude that a decreased bull:cow ratio (up to 1:73) did not affect natural service return to estrus pregnancy rate. Cattlemen may consider a reduced number of bulls needed for natural service breeding after FTAI, which can decrease bull related costs and increase the economic feasibility of adopting FTAI protocols.

scholarly journals Effect of a Trace Mineral Injection on Performance and Trace Mineral Status of Beef Cows and Calves

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2331
Author(s):  
Carmen J. Willmore ◽  
John B. Hall ◽  
Mary E. Drewnoski
Keyword(s):  
Pregnancy Rate ◽  
Reproductive Performance ◽  
Artificial Insemination ◽  
Beef Cows ◽  
Trace Mineral ◽  
Mineral Status ◽  
To Receive ◽  
Cu And Zn

The objective was to determine the effects of an injectable trace mineral (TMI; Multimin 90) containing copper (Cu), manganese (Mn), selenium (Se), and zinc (Zn) on trace mineral status and the resulting impacts on reproduction of beef cows and the growth of their calves. Beef cows (n = 200) were assigned to receive TMI or no injection (CON) prior to calving and breeding over two consecutive years. Calves born to cows receiving TMI also received TMI at birth in both years and at 49 ± 1.3 days of age in year 1. The TMI increased (p = 0.01) liver Zn and tended (p = 0.06) to increase liver Cu concentrations. Short-lived effects of TMI on Se were observed. Liver Cu and Zn would have been considered adequate and Se marginal in the CON. Pregnancy due to artificial insemination and overall pregnancy rate did not differ (p ≥ 0.36) between treatments. Use of TMI did not increase calf pre-weaning gain. These data indicate that TMI does not improve the reproductive performance of beef cows with adequate trace mineral status or the pre-weaning performance of their calves.

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.

PSIII-25 The effects of varying levels of trace mineral supplementation on mineral balance and antibody concentrations in feedlot cattle

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 287-288
Author(s):  
Brittany A Lippy ◽  
Blake K Wilson ◽  
Colton A Robison
Keyword(s):  
Negative Control ◽  
Feedlot Cattle ◽  
Trace Mineral ◽  
Herpesvirus Type ◽  
Diarrhea Virus ◽  
Mineral Supplementation ◽  
Normal Ranges ◽  
Bovine Herpesvirus Type 1 ◽  
Trends Over Time ◽  
Viral Diarrhea Virus

Abstract Trace mineral (TM) supplementation is critical for optimal performance and health. The objective was to determine the effects of varying levels of TM supplementation on feedlot cattle TM status and antibody concentrations. Angus steers (n = 240; BW = 291 kg ± 27.4) were stratified by arrival BW and source and assigned to 1 of 4 treatments (12 pens/treatment; 5 steers/pen). Treatments included a negative control (CON) in which cattle received no TM supplementation, a requirement treatment (1X) in which cattle received added TM at 2016 Nutrient Requirements of Beef Cattle required levels, a 2 times requirements (2X), and a 4 times requirements (4X) treatment. Selenium was included at 0.1, 0.2, and 0.3 mg/kg for 1X, 2X, and 4X respectively. Treatments were chosen based on reported TM supplementation levels from the 2015 Feedlot Consulting Nutritionist Survey. One steer was chosen at random from each pen to be evaluated for serum and liver TM status and antibody concentrations to respiratory viruses. There was treatment × day interaction for serum Co, and liver Cu and Se (P < 0.0001). Serum Co was greatest for the 4X treatment from d 28 through harvest. Liver Cu was greatest for the 2X and 4X treatments from d 56 through harvest. Liver Se was greatest for 2X and 4X from d 28 through harvest. There was an effect of day on liver Co, Fe, Mn, Mo, and Zn (P < 0.0001) and serum Cu, Mn, Mo, Se, and Zn (P < 0.0019). Concentrations for individual TM had different trends over time, however, all reported values were within normal ranges. Serum Zn was greater at harvest (P = .02). There was an effect of time on Bovine Viral Diarrhea Virus Type 1A, Bovine Herpesvirus Type 1, Bovine Parainfluenza 3 virus antibody titer concentrations (P < 0.0001).

Efficiency of mating, artificial insemination or resynchronisation at different times after first timed artificial insemination in postpartum Nellore cows to produce crossbred calves

2019 ◽  
Vol 59 (2) ◽  
pp. 225 ◽  
Author(s):  
Walvonvitis Baes Rodrigues ◽  
Jean do Prado Jara ◽  
Juliana Correa Borges ◽  
Luiz Orcirio Fialho de Oliveira ◽  
Urbano Pinto Gomes de Abreu ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Breeding Season ◽  
Chorionic Gonadotropin ◽  
Artificial Insemination ◽  
Fixed Time ◽  
Beef Cows ◽  
Device Removal ◽  
Oestradiol Benzoate ◽  
Timed Artificial Insemination ◽  
Equine Chorionic Gonadotropin

The objective of this trial was to evaluate different post-timed artificial insemination (TAI) reproductive managements in postpartum beef cows to produce crossbred calves from artificial insemination (AI). Nellore cows (n = 607), with 45 days postpartum, were inseminated at a fixed time, using a protocol that included an intravaginal progesterone-releasing device along with oestradiol benzoate, prostaglandin, equine chorionic gonadotropin, and oestradiol cypionate, followed TAI 48 h post-device removal. Four post-TAI treatments were evaluated: in CONTROL (T1, n = 161), cows were exposed to Nellore clean-up bulls until the end of the breeding season (75 days). In OBSERVATION (T2, n = 132), heat detection was performed for 15–25 days post-TAI, followed by AI. In RESYNC22 (T3, n = 157) and RESYNC30 (T4, n = 157), resynchronisation started after 22 or 30 days, following second TAI at Day 32 or 40 days after first TAI. In T2, T3 and T4, after the second AI, cows were exposed to Nellore clean-up bulls until the end of the breeding season (75 days). The pregnancy rate (PR) for the first TAI did not differ (54.6%, 53.0%, 59.2%, and 51.6% for CONTROL, OBSERVATION, RESYNC 22, and RESYNC 30, respectively; P = 0.66), and no difference was observed for the second TAI (RESYNC 22 = 45.31% and RESYNC30 = 46.05%; P = 0.137), in the PR at the end of the breeding season (86.33%, 86.36%, 78.98%, and 81.52%, P = 0.43), or embryonic losses (4.54%, 2.85%, 6.45% and 7.40%, respectively; P = 0.61), but the percentage of crossbred pregnancy was higher in groups with resynchronisation (RESYNC22 and RESYNC30) than CONTROL and OBSERVATION (98.38%, 90.62%, 63.30%, 78.95%, P < 0.001). In conclusion, resynchronisation programs of 22 or 30 days are more efficient to produce AI products, and the final pregnancy rate is similar among the treatments, differing only in the amount of calves produced by AI.

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