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We estimate a hedonic pricing model to determine producers’ value for bull expected progeny differences (EPDs), genomic-enhanced EPDs, and phenotypic traits. Birth weight EPD, ribeye area EPD, sale weight, age, frame score, and other factors had a statistically significant impact on bull prices. GE-EPDs were not associated with a change in the bull sales prices expect for weaned calf value and birth weight EPDs. Including weaned calf value and GE-EPDs in a bull hedonic pricing model provides a unique contribution. The results from this work will inform educational programming for bull purchasers on using new economic selection indices and GE-EPDs.

The objective of this experiment was to determine if circulating concentrations of pregnancy associated glycoproteins (PAG) on day 24 of gestation can be utilized to diagnose pregnancy and embryo viability in beef cattle. Postpartum beef cows (n = 677) and heifers (n = 127) were exposed to a 7-day CO-Synch + CIDR estrus synchronization protocol followed by fixed-time AI (FTAI) on day 0. Blood samples were collected at day 24 after TAI to assess circulating concentrations of PAG utilizing an in-house ELISA. Pregnancy diagnosis was performed 30 and 100 days after FTAI via transrectal ultrasonography. Mean circulating PAG concentration at day 24 differed (P 0.001) between animals diagnosed pregnant and non-pregnant at day 30 (1.69 ± 0.10 ng/mL vs 0.30 ng/mL ± 0.07 ng/mL; mean ± SEM; respectively). Pregnant heifers had increased PAG concentration at day 24 compared with pregnant cows (P 0.01; 3.29 ± 0.36 ng/mL vs 1.39 ± 0.10 ng/mL, respectively). Based on receiver operating characteristic (ROC) curve analysis, serum concentration of PAG at day 24 ≥ 0.33 ng/mL in cows and ≥0.54 ng/mL in heifers was 95% accurate at determining pregnancy status at day 30. Heifers that experienced late embryonic mortality between day 30 and 100 of gestation had decreased circulating concentrations of PAG on day 24 (2.02 ng/mL ± 0.73) compared with heifers that maintained an embryo until day 100 (3.69 ng/mL ± 0.39; P = 0.02). However, there was no difference in day 24 PAG concentration (P = 0.39) between cows that maintained or lost a pregnancy (1.31 ng/mL ± 0.25 vs 0.92 ng/ml ± 0.50). In summary, circulating PAG concentration on day 24 of gestation may be a useful marker for early pregnancy detection in beef cattle, and might be a potential marker for predicting embryonic loss.

We estimate the values of bull phenotypic traits, performance measurements, and expected progeny differences (EPDs) over time using bull sale data from an auction in Tennessee from 2006 to 2016. Moreover, we determine how a state partial-cost reimbursement program for bulls with certain EPDs affects bull sale price. Purebred seed stock producers in this region should focus on selling large, fast-growing, mature bulls that produce lighter calves for reduced calving stress. The state cost-share payment did not significantly increase bull prices in most years, meaning this payment was retained by cow-calf producers in most years.

Demonstrating the implementation of, and results from, applied management technologies on privately held farms is an essential method for Extension educators. A commercial cow/calf herd, for which the management was being transitioned to a younger family member, was used for this multi-year demonstration. Beginning summer 2019, the cow herd was inventoried and evaluated, and a plan was put in place to improve profitability through enhanced reproductive management. Initial evaluation showed an overall pregnancy rate of 75.6% with a 153 d calving season for cows and breeding age heifers (n = 209). Non-pregnant and un-sound cattle were sold (n = 56). The average initial BCS was a 4.5 (1 to 9 scale). Estrus synchronization for natural service was utilized in the first breeding season (Fall 2019) to condense the subsequent calving season. Melengestrol acetate (MGA) was fed at a rate of 0.5 mg/head/d for 7 d and bulls introduced on he last day MGA was fed. Also in year 1, timed artificial Insemination was used to breed purchased (n = 37) and home raised (n = 18) replacement heifers. A group of pregnant cows ranging in age from 5 to 8 years (n = 47) were also purchased in year 1. Ultrasonography was used to detect pregnancy and estimate calving date on 30 d post AI, and 30 d post bull removal. Year 2 pregnancy rate was 93% for heifers and 88% for cows with a 131 d estimated calving interval for all cows and heifers (n = 255), with 94% expected to calve in the first 90 days. In summary, while it is difficult to eliminate year-over-year variables, a combination of culling strategy and estrus synchronization for both natural service and AI resulted in an increased proportion of cows and heifers calving earlier in the calving season, which is expected to improve marketing potential and profitability of the resulting calf crop. Condensing the calving interval provides opportunity to introduce additional reproductive management practices. Results from this demonstration will be incorporated into Extension educational curricula.

With the objective of continuing educational delivery while county Extension offices were unable to host large group meeting due to pandemic response regulations, a series of webinars were developed as a component of the Tennessee Master Beef Producer program. A secondary objective was to maintain a county-based approach to programmatic delivery. To reach these objectives, individual webinars (Zoom Video Communications, San Jose, CA; n = 9), each lasting approximately 1.5 hr were developed by UT Extension Specialists and offered between October and November of 2020 covering the topics of breeding and genetics, reproductive management, nutrition, animal handling, economics, health management, and forages. Questions were administered during the live session via the Zoom polling function to assess production statistics and collect evaluation data. The series was advertised in local communities through UT Extension County Agents. Agents were given the opportunity to choose as many or as few to incorporate into their local delivery and could choose to give producers the option of viewing at home, at socially distanced group meetings, or either. Interaction was limited to the chat function within Zoom with the expectation that attendees would make audio and video interaction difficult to manage. Total live participation was 8,009 and averaged 890 ± 15.3 unique views per session. Each webinar was recorded and posted to YouTube to be used by agents for later delivery. In-webinar polling showed that an average of 91% of the webinar participants planned to implement a change on their operation as a direct result of information provided in the presentation. Post-webinar Likert scale (1 to 5) analysis of participants indicated approval of speaker ability (4.52 ± 0.03) and content quality (4.51 ± 0.03). These results indicate a high adoption rate by agents and that webinars are an effective tool for achieving behavioral change through a county-based Extension system.

The development of replacement heifers is crucial for breeding success and herd efficiency. Nutritional management can affect not only reproductive development but also the inflammatory status of the uterine environment, which may impact reproductive functions such as pregnancy establishment and development. The study herein evaluated the concentration of cytokines and chemokines in the uterus of heifers supplemented with different levels of protein. Angus heifers (n = 60) were blocked by body weight (BW) and randomly assigned to 1 of 3 treatments based on protein supplementation level: control of 10% crude protein (CON), 20% crude protein (P20), or 40% crude protein (P40). BW, body condition score, and blood samples were taken every 2 wk for 140 d to monitor development. Uterine flushes were performed monthly and concentrations of cytokines (IL-1α, IL-1β, TNF-α, IFN-γ, IL-10, VEGF-α, IL-17A, and IL-36RA) and chemokines (IL-8, MCP-1, MIP-1α, and MIP-1β) were quantified via ELISA multiplex. To test if there were mean differences in cytokines between the treatment groups or over time, PROC GLIMMIX (SAS v 9.4) was utilized. Concentrations of all cytokines and chemokines, except IL-1α, changed throughout heifer development (P < 0.05). Heifers in the P40 treatment group displayed reduced concentrations of MCP-1 (P = 0.007) and tended to have decreased concentrations of IFN-γ (P = 0.06). Cytokine IL-36RA tended (P = 0.06) to be affected by protein level, with the lowest concentrations observed in CON heifers. Most cytokines and chemokines increased following the initial month of supplementation (P < 0.05). The increase in concentrations after 1 mo may indicate an adaptive response in the uterus to diet change. Cytokines and chemokines fluctuated due to physiological changes occurring during development. Further research is needed to determine the influence of nutrition on uterine inflammation and long-term impacts on reproductive function.

Price determinants for bulls, cows, and feeder cattle are well established in the literature but there has been little research on bred heifer price determinants and specifically the impact of feeder cattle prices on the purchase price of bred heifers. We estimated the impact of reproductive characteristics and feeder cattle prices on bred heifer prices for beef production. Data were obtained from a May and November bred heifer sale located in Kentucky and hedonic pricing models were estimated for bred heifers for each sale month. Prices for fall- calving heifers were influenced by number of months bred or expected calving date with longer bred heifers priced the highest. Purchase price of spring- calving heifers did not vary from five to seven months bred, but heifers four months bred were priced lower. Pregnancies resulting from artificial insemination did increase the value of fall-calving heifers but did not impact spring-calving heifer prices. Heifer feeder cattle prices the day of the sale positively influenced the price of spring- and fall-calving bred heifers. This extends previous research by considering the impact of feeder cattle prices on the price of bred heifers. The results can help cow-calf producers in making a more informed purchasing decision of replacement breeding animals.

Preparing agricultural producers to cope with volatile weather changes, specifically drought, requires a better understanding of forage water-use efficiency (WUE) potentials. Options to improve farm resiliency to drought may include the use of C4 annual and perennial forages, which have greater production efficiency during drought than commonly used C3 forages. Our objective was to measure WUE through real-time gas exchange measurements of photosynthesis and transpiration in (1) a greenhouse study and (2) under field-grazing conditions. Growth parameters, instantaneous water use efficiency (iWUE), and mass-based WUE (mWUE) data were collected under greenhouse conditions in Study 1 for the following species: crabgrass (Digitaria sanguinalis cv. &lsquo, Red River&rsquo, ), switchgrass (Panicum virgatum cv. &lsquo, Alamo&rsquo, ), big bluestem (Andropogon gerardii cv. &lsquo, OZ-70&rsquo, ), indiangrass (Sorghastum nutans cv. &lsquo, Rumsey&rsquo, ), eastern gamagrass (Tripsacum dactyloides cv. &lsquo, Pete&rsquo, ), bermudagrass (Cynodon dactylon cv. &lsquo, Vaughn&rsquo, s #1&rsquo, ), sorghum-sudangrass (Sorghum bicolor (L.) &times, Sorghum sudanese (P.) cv. &lsquo, Greengrazer&rsquo, ), and tall fescue (Schedonorus arundinaceus (Schreb.) Dumort). Study 2 occurred from 2014 to 2016, and evaluated iWUE of crabgrass, switchgrass, bermudagrass, eastern gamagrass, and a big bluestem/indiangrass mix under field conditions. Overall, in situ iWUE of crabgrass, switchgrass, eastern gamagrass, and bermudagrass did not differ, while iWUE of the big bluestem/indiangrass was less than switchgrass and crabgrass, an advantage for these species if the standardized precipitation index drops below zero. Bermudagrass, switchgrass, sorghum-sudangrass, pearl millet, and indiangrass had comparable mWUE values under greenhouse-simulated drought. These results will aid in the development of forage species recommendations for mitigating drought and improving resiliency.

Developing livestock and equine trainings to empower county Extension agents is challenging, especially when spanning in-person and online delivery modules. Real life application of training concepts is difficult, particularly when participants have varied backgrounds and experience. Thus, we assessed if scenario-based training modules were an effective training method across in-person and virtual formats. The same scenario-based training was delivered at three, regional in-person trainings (n = 42), and one virtual training (n = 32). Training format consisted of four, species-specific lectures addressing various production topics. Small groups then developed recommendations for a specific scenario, followed by a debriefing session consisting of group reactions and specialist recommendations. Topic-area application to county programs, instructor effectiveness, and overall benefit of the training session were evaluated (Qualtrics, in-person n = 26, 62% completion; virtual n = 17, 53% completion). Data were assessed using analysis of variance and mean comparisons (α=0.05), with Tukey’s pairwise post hoc analysis where appropriate (STATA 16). Across all sessions, likert scale responses (1=poor and 5=excellent, n = 43) indicated lecture sessions were applicable to county areas of need across material content (mean±SD, cattle=4.71±0.57, equine=4.64±0.50), teaching effectiveness (cattle=4.77±0.42, equine=4.75±0.43), and overall quality (cattle=4.68±0.57, equine=4.67±0.51), respectively. Scenario-based training benefit was not influenced by the number of times an agent had attended in-service training on livestock species, agent appointment (youth vs. adult educator), or training location (p >0.05). Attendance at previous in-service trainings (cattle P = 0.005; equine P = 0.013) and agent appointment (cattle P = 0.0006; equine P = 0.05) had a significant impact on the number of questions agents reported to have received on scenario topics in the last 12 months. More topic area questions were reported by agents with adult education responsibilities and previous training attendance. Based upon these results, scenario-based training is an effective in-person and virtual training tool for 4-H and adult Extension agents of varying experience.

Induced ovulation of small pre-ovulatory follicles reduced pregnancy rates, embryo survival, day seven embryo quality, and successful embryo cleavage in beef cows undergoing fixed-time artificial insemination. RNA-sequencing of oocytes and associated cumulus cells collected from pre-ovulatory follicles 23 h after gonadotropin-releasing hormone (GnRH) administration to induce the pre-ovulatory gonadotropin surge suggested reduced capacity for glucose metabolism in cumulus cells of follicles ≤11.7 mm. We hypothesized that the follicular fluid metabolome influences metabolic capacity of the cumulus-oocyte complex and contributes to reduced embryo cleavage and quality grade observed following induced ovulation of small follicles. Therefore, we performed a study to determine the correlation between pre-ovulatory follicle diameter and follicular fluid metabolome profiles in lactating beef cows (Angus, n = 130). We synchronized the development of a pre-ovulatory follicle and collected the follicular contents approximately 20 h after GnRH administration. We then performed ultra-high performance liquid chromatography—high resolution mass spectrometry (UHPLC-HRMS) metabolomic studies on 43 follicular fluid samples and identified 38 metabolites within pre-ovulatory follicles of increasing size. We detected 18 metabolites with a significant, positive correlation to follicle diameter. Individual and pathway enrichment analysis of significantly correlated metabolites suggest that altered glucose and amino acid metabolism likely contribute to reduced developmental competence of oocytes when small pre-ovulatory follicles undergo induced ovulation.

The use of high-energy diets to develop bulls is perceived to influence semen quality, yet little research has been conducted using iso-caloric diets that differ in form or feeding management strategy. Therefore, the objective of this experiment was to evaluate the effects of two feeding strategies on growth performance and semen quality of developing bulls. Angus bulls (n = 48; 332 ± 47 d of age) were stratified into one of sixteen drylot pens before pens were randomly assigned to one of two iso-caloric diets: a total mixed ration (TMR; n = 8 pens) or a component-based ration (COMP; n = 8 pens) fed for 84 d. Rumen pH was continuously monitored via rumen boluses and dry matter intake (DMI) was measured daily throughout the experiment. Backfat thickness and hoof conformation were measured on d 0 and 84, with body weight measured and semen collected at 21-d intervals. Semen was assessed for progressive motility, total sperm per ejaculate, and sperm cell morphology. Data were analyzed via ANOVA utilizing JMP 13.0. Bulls fed the COMP ration had a greater DMI (P < 0.01) and ADG (P < 0.01), but similar feed efficiency (P = 0.21) when compared to TMR-fed bulls. Bulls fed COMP tended to have a lower mean rumen pH (P < 0.10). Additionally, COMP-fed bulls had greater backfat thickness (P < 0.01) but similar hoof conformation scores (P = 0.26) when compared to TMR-fed bulls on d 84. Feeding strategy did not affect progressive motility (P = 0.34), total sperm per ejaculate (P = 0.81), or percent morphologically-normal sperm (P = 0.31). These results suggest that the feeding strategies utilized in this experiment affected growth performance, rumen pH, and adiposity without influencing semen quality of developing bulls, and therefore should not be expected to influence breeding soundness examination outcomes.

Little is known about the impact of a supplemental prepartum feed ration for cows on the profitability of their calves. Therefore, we investigated the impact of animal characteristics and a supplemental prepartum feed program for cows on net returns to finished steers and the probability of a steer grading Choice or higher. Data were collected for 160 Tennessee steers that were finished in a feedlot. The supplemental prepartum feeding program decreased net returns of finished steers. Several animal characteristics were found to influence net returns of finished steers and the probability of a steer grading Choice or higher.

Nutrition is a major component in successful heifer development, influencing age at puberty and the uterine environment, therefore, impacting reproductive efficiency. Different diets can influence systemic inflammation, however, the effect on uterine cytokines has not been determined. Our objective was to evaluate the effect of varied levels of dietary protein on inflammatory cytokines in the uterine environment of developing heifers. Commercial Angus heifers (n = 60) were blocked by body weight, then allocated to receive one of three dietary protein supplementation treatments (n = 20 per group, n = 5 per pen): 10% crude protein (CP; 100% corn), 20% CP [75% dried distillers’ grains (DDG) 25% corn], or 40% CP (75% soybean meal 25% DDG). Supplements were provided four times weekly for six months with ad libitum native grass hay, mineral supplement, and water. Body weight, BCS, and blood was taken every 14d. Uterine fluid was collected every 28d to determine presence of cytokines IL1α, IL1β, TNFα, IFNγ, IL10, IL4, and IL6. The GLIMMIX procedure (SAS 9.4) was used with fixed effects of supplementation, month, and their interaction; random effects of block, interaction of block and supplementation, and heifer within the interaction; and repeated measure of month. Concentrations of IL1β, TNFα, IFNγ, and IL10 shifted throughout development (P < 0.0002). Cytokine IFNγ was also affected by month of development (P = 0.002) and tended (P = 0.06) to decrease as CP increased. Presence of each cytokine was then recorded as binary and analyzed by the frequency procedure (SAS 9.4) to determine a uterine cytokine profile. Pro-inflammatory cytokines IL1α, IL1β, and TNFα occurred together more frequently following the beginning of supplementation. In conclusion, inflammatory cytokines shift throughout heifer development, potentially leading to differences in future reproductive success. Further research is needed to determine the dietary influence for optimal uterine environment development.

Growing concern over breeding soundness examination failures has led to increased interest in identifying factors that may influence semen quality of developing bulls. An experiment was conducted to evaluate relationships between semen quality and scrotal circumference, adiposity, and rumen conditions of Angus bulls (n = 48; 332 ± 47 d of age) that were developed over an 84-d period. Bulls underwent breeding soundness examinations at each of four 21-d intervals. Backfat thickness was measured on d 0 and 84, and rumen pH and temperature were continuously monitored throughout the experiment via rumen boluses (eBolus; eCow, Devon, UK). Simple linear regression was conducted (JMP 13.0; SAS Institute Inc., Cary, NC) to determine independent relationships between semen characteristics and respective explanatory variables. Change in scrotal circumference between d 0 and 84 was directly related to change in percent morphologically-normal sperm (R2 = 0.12; P < 0.05), but no other semen quality characteristics (P ≥ 0.17). Change in backfat thickness throughout the experiment tended to be inversely related to change in percent morphologically-normal sperm (R2 = 0.06; P < 0.10), but was directly related to changes in semen volume (R2 = 0.10; P < 0.05) and total sperm per ejaculate (R2 = 0.12; P < 0.05), but not change in motility (P = 0.24). Mean rumen pH tended to be directly related to changes in semen volume (R2 = 0.07; P < 0.10) and total sperm per ejaculate (R2 = 0.07; P < 0.10), but not changes in motility (P = 0.28) or percent morphologically-normal sperm (P = 0.94). Mean rumen temperature was not related to any semen quality characteristics (P ≥ 0.15). Collectively, these results suggest that rumen pH, as well as changes in scrotal circumference and adiposity are related to and independently explain variation in semen quality of developing bulls.

Excitable cattle are dangerous to personnel and have reduced individual performance. The aim of this study was to 1) identify objective criteria for evaluating bull temperament and 2) examine relationships among temperament, behavior, and performance of bulls during an 84-d performance test. Angus bulls ( = 60) were reared in 6 pens based on BW and age. Pen scores (PS; 1 = docile and 5 = very aggressive) were assigned on d -1, 27, 55, and 83. Exit velocity (EV), BW, time to exit the chute, and order through the chute were recorded on d 0, 28, 56, and 84. The ADG was calculated for the 84-d test period, and ultrasound data and frame score calculations were recorded on d 84. Dataloggers measured steps taken, lying time, number of lying bouts, and lying bout duration of bulls ( = 27; 3 pens) from d 3 to 28 and d 59 to 84. Bulls with a d -1 PS of 1 or 2 were categorized as calm (PScalm; = 40), whereas bulls with a PS of 3 or 4 were categorized as excitable (PSexcitable; = 20). Bulls were separated into 2 groups based on the bottom 20 EV (EVcalm) and top 20 EV (EVexcitable) on d 0. Mixed model ANOVA (SAS 9.3) was used to compare groups for the two temperament assessment methods, behavior, and growth performance. Mean EV decreased ( < 0.05) by d 84. Total lying time from d 3 to 28 was greater ( < 0.05) for PScalm bulls when compared with PSexcitable bulls. However, total lying time from d 59 to 84 was greater ( < 0.05) for EVexcitable bulls when compared with EVcalm bulls. Regardless of initial contemporary group assignment, all bulls exited the chute slower ( < 0.001) on d 84 than on d 0. The PSexcitable bulls had greater ( < 0.01) frame scores and greater ADG than PScalm bulls. The PSexcitable bulls had more ( < 0.01) backfat than PScalm bulls. However, ribeye area was smaller ( < 0.01) in EVexcitable bulls than EVcalm bulls. Based on these results, bulls appeared to have habituated over the testing period. Additionally, the potential lack of innate temperament variation may have attributed to the little difference seen among the behavioral and performance data. Therefore, temperament should be reassessed within a novel environment with new handlers to differentiate between the bull's true temperament and its ability to habituate.

The aim of this study was to examine relationships among temperament, endocrinology, and reproductive parameters of bulls enrolled in an 84-day performance test. Angus bulls (n = 60) were housed in six pens grouped by age and weight. Pen scores (PS; 1 = docile to 5 = very aggressive) were assigned on Days -1, 27, 55, and 83 of the performance test. On the following day, blood and hair samples were collected, and body weight (BW) and exit velocity (EV) were recorded. Bulls were split into two categories based on; Day -1 PS (PScalm = PS 1 or 2; PSexcitable = PS 3 or 4) and Day 0 EV (EVcalm = slowest 20 bulls; EVexcitable = fastest 20 bulls). Cortisol and testosterone concentrations in serum and hair did not differ (P 0.10) between PS or EV temperament categories. Sampling day differences (P 0.01) occurred for serum testosterone, hair cortisol, and hair testosterone concentration; however, serum cortisol concentration did not differ (P 0.10) over the sampling days. Serum testosterone concentration increased (P 0.01) from Day 0 to 28, decreased from Day 28 to 56, but Day 84 did not differ from Day 0, 28, or 56. Hair cortisol concentration was greatest (P 0.01) on Day 0, decreased from Day 28 to 56 but did not differ from Day 56 to 84. Hair testosterone concentration was greatest (P 0.01) on Day 0 and remained constant from Day 28 to 84. Bulls categorized as PScalm had a greater (P 0.01) percentage of normal sperm and secondary defects (P 0.01) when compared with PSexcitable bulls. However, EVcalm bulls had fewer (P 0.01) primary defects but more (P 0.01) secondary defects than EVexcitable bulls. In conclusion, bulls exhibited physiological evidence of acclimation during the test as indicated by a reduction in hair cortisol concentration. In addition, the ability of the bulls to acclimate while residing at the testing center may have contributed to little differences observed during the breeding soundness examination portion of the performance test.

The primary objective of this study was to identify if reproductive tract size-position score (SPS) and estrus expression prior to artificial insemination (AI) influences concentration of pregnancy-associated glycoproteins (PAGs) and pregnancy success. Angus females (n = 1397) were FTAI’d to Angus sires at d 0 after estrus synchronization using a 7-day CO-Synch CIDR protocol. Reproductive tract SPS were assigned on d 0 as SPS1 as small and compact resting within the pelvic cavity; SPS2 as intermediate, resting partially outside the pelvic cavity; and SPS3 as larger and resting outside the pelvic cavity. Estrotect patches received scores on d 0 of 1 (< 25% activation), 2 (< 50% activation), 3 (< 75% activation), or 4 (>75% activation) where patch scores of 1 and 2 signified no estrus expression, whereas scores of 3 and 4 indicated estrus expression. Pregnancy diagnosis was performed by ultrasound on d 30 after FTAI and serum samples were also collected on d 30 of gestation for quantification of PAGs. SPS3 females were more likely to exhibit estrus compared to both SPS1 (P = 0.0107) and SPS2 (P = 0.0291) females (48.98% vs 35.42% and 37.98%, respectively). Circulating PAG concentrations were significantly higher among females that exhibited increased estrus intensity compared to females that exhibited no estrus activity (P = 0.0023). Reproductive tract SPS by PAGs was not significant when parity was included as a covariate in the model (P > 0.05). Pregnancy loss did not correlate with reproductive tract SPS or estrus expression (P > 0.05); however, females that exhibited estrus at TAI did have a significantly higher pregnancy rate at d 30 of gestation (P < 0.0001) and AI calving rate (P = 0.0280) compared to females that did not show estrus. In summary, estrus is associated with increased pregnancy rates and SPS3 females exhibited estrus more frequently.

The objective of this experiment was to evaluate the biostimulatory effect of bull exposure, with or without the deposition of seminal plasma, on expression of estrus and pregnancy rate to AI in cattle. Beef heifers (n=86) and cows (n=193) were allocated to one of three treatments: (1) no bull exposure (CON; n=95), (2) exposure to a bull with a surgically-deviated penis for 21 d prior to AI (DB; n=88), or (3) exposure to a vasectomized bull for 21 d prior to AI (VB; n=96). The DB treatment provided the physical presence of a bull but prevented intromission, whereas the VB treatment allowed for intromission and deposition of seminal plasma but not spermatozoa. The estrous cycles of all females were synchronized using the Select Synch+CIDR protocol (GnRH+CIDR-7d-CIDR removal+PGF(2α), detection of estrus+AI 12h later for 84 h-clean-up TAI+GnRH). Pregnancy was detected via transrectal ultrasonography on d 35 post-AI. At the onset of the experiment, 75.7% of heifers and 86.1% of cows were estrous cycling. The percentages of females that displayed estrus were similar (P>0.05) among treatments (71.4%, 76.8%, and 74.4% for CON, DB, and VB, respectively). Pregnancy rates tended to be greater (P=0.06) in females in the DB treatment (60.5%) compared to females in the VB treatment (42.2%), with the control group intermediate (49.5%). In conclusion, biostimulation did not affect the expression of estrus but females exposed to the DB treatment tended to have an increased pregnancy rate.