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Transrectal ultrasonography is known as the gold standard for pregnancy detection, but requires costly equipment and technical skills; therefore, access to an inexpensive and more user-friendly method with similar accuracy could benefit cattle producers. Detection of pregnancy-associated glycoproteins can accurately determine pregnancy in ruminants; however, usually requires specialized equipment for the assay. Thus, the objectives of these studies were to 1) validate the IDEXX Alertys OnFarm Pregnancy Test (lateral flow) and compare the accuracy of all three commercial PAG assays to transrectal ultrasonography and 2) to determine the postpartum interval necessary for clearance of pregnancy-associated glycoproteins from the previous pregnancy to avoid false positives. In study 1, blood samples from previously identified pregnant Bos taurus females from six different herds (nulliparous n = 1,205 and multiparous n = 1,539; samples collected between d 27 to 285 of gestation over a three-year period) were utilized. In study 2, postpartum females (primiparous n = 48 and multiparous n = 66) from one herd were utilized: (n = 1,066; samples collected weekly for up to 12 weeks postpartum). In study 1, level of agreement between different methods of pregnancy detection was determined by Pearson's correlation and Kappa scores. In study 2, data were analyzed as a repeated measure using the MIXED procedure of SAS with main effects of parity, days postpartum (dpp), and parity by days postpartum, then data were analyzed further using the REG procedure of SAS. In study 1, transrectal ultrasonography and lateral flow were positively correlated (r = 0.77; P <0.01), with 92.4% agreement. In study 2, the abundance of absorbance of PAGs rapidly decreased from 0 to 50 days postpartum, then continued to gradually decrease (P <0.01; r = 0.90). Prior to 42 days postpartum, PAG concentrations were sufficiently elevated resulting in false positive readings in all assays. In conclusion, there is very good agreement between transrectal ultrasonography and PAG assays, but likelihood of false positive results are highif assays are performed fewer than 42 days postpartum. [ABSTRACT FROM AUTHOR]

The purpose of this study is to determine student’s perceived value of on-farm, technical training at a university farm. Specifically, this study evaluates students use and non-use of the university farm and the student’s perception of this use on overall academic competency and career readiness. The target population of the study included all students enrolled within a College of Agriculture. The study uses both an online survey instrument requesting demographic information and uses and value of the farm as well as three focus groups. Results indicate that the primary reasons students do not utilize the farm more include lack of coursework using the farm and lack of available activities utilizing the farm as well as communication. However, students did report that the time and activities they have completed at the farm have been practical, desirable for future employers, and made a valuable contribution to their education. [ABSTRACT FROM AUTHOR]

Pregnancy detection is an extremely valuable practice in animal production systems as it allows for identification of pregnant or nonpregnant females and thus contributes to informed management decisions. Unfortunately, blood pregnancy tests simply provide a yes or no answer to pregnancy status. Multiparous ewes (n = 20) at the Arkansas State University Teaching and Research Center were enrolled in a study to evaluate whether lamb number or sex would impact commercial blood pregnancy test results. Weekly blood samples were collected, for a total of 5 blood samples during the breeding season (11/14/22, 11/21/22, 11/28/22, 12/5/22, and 12/12/22) ewes were followed through lambing to determine lamb number and sex. Whole blood samples were centrifuged at 2,000 x g and plasma harvested and stored at -20 C until analysis for pregnancy associated glycoproteins was completed. Plasma samples were analyzed using two commercially available blood pregnancy tests, Rapid Visual Pregnancy Test (RV plate) and OnFarm Pregnancy Test (SNAP). The RV Plate is a 96-well ELISA test that is designed to be interpreted visually by comparison with the positive (PC) and negative (NC) control wells. The RV Plate and SNAP tests were completed, and results interpreted by two technicians blind to pregnancy status using a scoring system (0 = same or less color than NC; 1 = slightly more color than NC; 2 = slightly less color than PC; 3 = same or more color than PC; 0 and 1 = not pregnant, 2 and 3 = pregnant) or by manufacturer's instructions (SNAP). Lambing revealed a total of 18 female lambs and 13 male lambs born to the 20 ewes, furthermore, there were 6 singleton, 11 twins, and 1 set of triplets. Total score count results from the RV Plate indicate that as gestational age increased the number of 3 scores increased (11/14/22 = zero scores of '3'; 12/12/22 = 55 scores of '3'), however, overall, there were no statistical differences in pregnancy status across ewes (P = 0.78). All SNAP test results were immediate and positive for pregnancy for all collections apart from one ewe, 9113, with a conception date of 10/19/22. Ewe 9113 SNAP test result for the first collection was "not pregnant", and for the second collection date, a positive result did not appear until 5 min and 43 sec. Lambing revealed that 9113 had a singleton female lamb. Based on the present study, sex and number of lamb offspring could not be determined by commercial blood pregnancy tests. In the present study, the earliest confirmed pregnancy determined retrospectively by subtracting average ewe gestation length (152 d) from the lambing date was determined to be September 28th but blood sampling and testing for PAGs did not begin until November 14th, therefore, further studies are needed that initiate blood sampling sooner. [ABSTRACT FROM AUTHOR]

Cryopreservation of semen has allowed for the global spreading of genetic material across several different species. Semen cryopreservation and artificial insemination allow for even small flocks to incorporate superior genetics from all over the world. This research aimed to determine differences in postthaw caprine semen characteristics based on the type of extender used during preservation. A variety of both meat and dairy breeds were used for this study, including Boer (n = 3), Nigerian Dwarf (n = 3), and Saanen (n = 2). Bucks were collected by artificial vagina and ejaculates were assessed for quality control using iSperm (Initial) before processing. Samples were divided evenly across treatments per collection date (3 to 4 collections per buck). Each ejaculate was divided into three equal portions for the study (CONTROL: egg yolk-based extender, SOY: soymilk-based extender, and UHT: ultra-high temperature milk-based extender). Post-thaw sperm parameters were evaluated across treatments using iSperm at hours 0 (PT0h) and 2 (PT2h) and were compared with fresh (Initial) characteristics and to the other treatments. Characteristics evaluated included total motility, and proportion of samples above 30% motility at PT0h (minimum motility standard). For motility, there were effects of extender type (P < 0.0001), breed (P < 0.01), time (P < 0.0001), and interactions of breed by time (P = 0.04) and time by extender (P < 0.0001). CONTROL had 61.9% motility and was greater (P < 0.0001) than UHT which had 39.4% motility, and both CONTROL and UHT had greater (P ≤ 0.0003) motility than SOY (21.7%). The Saanen buck motility was 49.1% and was not different (P = 0.15) from Nigerian 41.5%, and both Saanen and Nigerian had greater (P ≤ 0.01) motility than Boer which was 29.8%. Post-thaw motility at PT0h was 27.0% and at PT2h was 21.7% and both were less than the initial motility of 74.0%, this same pattern was observed within the breed by time interaction where initial motility was greater (P < 0.0001) than both PT0h and PT2h which were not different (P ≥ 0.06). There was no difference in motility for Initial across the different extender types (72.9%, 75.9%, and 72.9% for CONTROL, UHT, and SOY, respectively; P ≥ 0.54). For both PT0h and PT2h, CONTROL (60.9% and 50.3%, respectively) had greater (P < 0.0001) motility than UHT (23.5% and 22.0%, respectively) and SOY (9.5% and 6.9%, respectively). The UHT had greater (P ≤ 0.002) motility than SOY at both PT0h and PT2h. Extender type affected the proportion of samples that reached the minimum motility standard (P < 0.0001) where 96.3% of CONTROL had motility greater than 30% while UHT and SOY had 42.5 and 0%, respectively. Although CONTROL extender resulted in more samples of greater quality, UHT extender is a valid option for caprine semen resulting in acceptable motility and quality post-thaw characteristics. SOY extender needs to be evaluated further before it can be used with caprine semen. [ABSTRACT FROM AUTHOR]

This experiment aimed to compare synchronization cost associated with two protocols: one utilizing estrus detection (6d; PG 6-d CIDR+TAI) and one utilizing strictly fixed-time artificial insemination (FTAI; 7d; 7-d CO-Synch+CIDR). Cows and heifers (n = 657) from 10 herds in three states were grouped by days postpartum and age, and randomly assigned to one of two protocols. Cows and heifers assigned to the 6 d protocol were administered prostaglandin F2a (PGF) on d-9, CIDR insertion and administration of gonadotropin-releasing hormone (GnRH1) on d -6, and CIDR removal and PGF administration on d 0. Cows and heifers that were assigned to the 6-d protocol were subsequently grouped into three treatments based on presence and/or timing of estrus and insemination (PG1: Insemination before CIDR insertion, n = 136; PG2: Insemination after CIDR removal, n = 26; T6: Insemination at TAI, n = 166). Cows and heifers assigned to the 7-d protocol (T7: Insemination at FTAI, n = 329) were administered GnRH1 and CIDR insertion on d -7, followed by CIDR removal and PGF administration on d 0. For all animals, FTAI and GnRH2 administration occurred at 54 h (heifers) or 66 h (cows) after CIDR removal. Pregnancy was determined from d 30 to d 40 after FTAI by transrectal ultrasonography. Total cost and profit per pregnancy was calculated for herds of 30, 100, 300, and 500 females with varying estrus response and pregnancy rates. Expenditures were calculated assuming synchronization costs (PG1 = $46.15, PG2 = $75.05, T6 = $77.91, T7 = $73.72), general labor cost considering herd size and handling days, as well as estrus detection labor cost assuming $10.00 per h, a 95% overall herd pregnancy rate, a 1:40 bull:cow ratio, and average bull purchase price of $3,000.00. Revenue was estimated assuming a maximum 205-d weaning age, 1.09 kg/d gain, $200.00/45.4 kg, and 85% weaning rate. Differences in estrus response and pregnancy rate were determined using the GLIMMIX procedure of SAS (v9.4), including herd as a random variable. Estrus response was greater (P < 0.0001) in females assigned to the 6d (73 ± 4%) compared with the 7d (53 ± 4%) protocol; however, pregnancy success was similar among treatment groups (P = 0.32; PG1 = 45 ± 4%, PG2 = 58 ± 10%, T6 = 46±4%, T7 = 52±3%). At the observed estrus response and pregnancy rate for each treatment group, the 6d protocol resulted in a decreased cost per pregnancy compared with the 7d protocol [Table 1; herds of: 30 = ($3.53), 100 = ($5.16), 300 = ($6.58), 500 = ($7.00) females]. Additionally, using the same variables, the 6d protocol resulted in an increased profit per pregnancy compared with the 7d protocol (herds of: 30 = $3.50, 100 = $6.41, 300 = $17.27, 500 = $12.06 females). These results suggest that labor associated with estrus detection may be offset by the proportion of calves subsequently born earlier within the calving season, allowing for improvements to profitability, especially in larger herds. [ABSTRACT FROM AUTHOR]

It has been reported that plasma serine protease inhibitor (SERPINA5) and dystroglycan (DAG1) are loosely attached to the sperm and SERPINA5 can also be present on sperm tails. The objective of this study was to evaluate whether SERPINA5 and/or DAG1 could be used as a fertility marker in dairy bulls. Frozen semen from dairy bulls (n=19) were evaluated for concentration of SERPINA5 and DAG1 and percentage of sperm tail labeled for SERPINA5 (SERPINA5-tail) by immunofluorescence in a minimum of 200 sperm cells per bull in two different ejaculates. Semen was evaluated for total motility, progressive motility, and viability. Semen was used for in vitro embryo production (~150 oocytes/bull). Bull fertility was classified by two methods, sire conception rates [SCR - High-SCR (>1.0) or Low-SCR (< -4.0)] and the ratio of embryos that developed into a blastocyst (BL) from those that had cleaved (CL) as Good (BL/CL=38.5%) or Poor (BL/CL< 38.5%). The GLIMMIX procedure of SAS was used to evaluate fertility classification with SCR, BL/CL, and the interaction in the model with bull as a random effect. Progressive motility, CL, SERPINA5 and DAG1 concentration, and SERPINA5-tail did not differ (P=0.14) among SCR and BL/CL classifications or their interaction. There was no difference (P>0.33) in total motility between High-SCR and Low-SCR or BL/CL classification; however, the interaction was significant (P=0.02; High-SCR/Good 54.9±2.8%, High-SCR/Poor 39.4±5.4%, Low-SCR/Good 44.8±4.5%, Low-SCR/Poor 52.03±3.2%). High-SCR bulls had decreased BL (P=0.03; 30.6±1.6%, 35.8±1.4%, respectively) and tended to have decreased BL/CL ratio (P=0.10; 38.1±2.0%, 42.9±1.8%, respectively) compared with Low-SCR bulls. In summary, DAG1 and SERPINA5 do not seem to be a putative fertility marker. In vitro embryo production is not a good predictor of SCR, since High-SCR and Low-SCR bulls may have Good or Poor in vitro embryo developments. [ABSTRACT FROM AUTHOR]

Damage to the bovine corpus luteum (CL) has been reported following modified-live virus vaccination (MLV). The objective of this study was to investigate the degree of luteal apoptosis after MLV or inactivated vaccine (IV) administration at time of artificial insemination. Beef females were estrous synchronized and on d 0 were vaccinated with a MLV or IV after being transrectally ultrasounded to record presence and location of dominant follicles and CL. Thirteen cows (MLV, n=7; IV, n=6) were selected on d 10-13 across treatment based on dominant follicle size and estrus expression for ovariectomy. Ovaries were obtained and CL were frozen in OCT and sectioned for immunohistochemistry analysis. At the time of ovary collection, some MLV animals had two CL. These were characterized into old or new CL, relative to if ovulation had occurred in response to the synchronization protocol or afterward due to an abnormal cycle, respectively. For immunohistochemistry analysis, two nonconsecutive sections were evaluated for apoptosis using a TUNEL staining kit (ab66110) according to manufacturer's instructions, with the modification of DAPI being used as a cell marker. Two random fields of view from each section were photographed with a Keyence BZ-X810 microscope and were evaluated for number of total and apoptotic cells. The GLIMMIX procedure of SAS was utilized to analyze percentage of apoptotic cells with image included as a random effect. Percentage of apoptotic cells were affected by treatment (P < 0.0001). MLV-new CL had the greatest percentage (35.56 ± 5.5%) of luteal cell apoptosis, while MLV-old CL (7.05 ± 4.6%) and IV (4.24 ± 4.9%) were similarly decreased. In summary, a greater degree of apoptosis in new CL which formed after an abnormal cycle following MLV administration indicates the ability of MLV to induce estrous cycle dysfunction and extend its effects to luteal cell development and function. [ABSTRACT FROM AUTHOR]

Pre-synchronization has been evaluated as a method to improve synchrony of ovulatory follicles before fixed-time AI (FTAI). The objective was to compare FTAI results in beef cows from two protocols that utilize pre-synchronization. Blood samples were collected on d-14 (d0=CIDR removal) to determine progesterone concentration at the start of synchronization (P4start: =1ng/mL=high, < 1ng/mL=low). In a subset (n=1,032), an additional blood sample was taken between d-21 and -29 to determine cyclicity. Cows (n=1,119), from 21 herds, were grouped by days postpartum and age and randomly assigned to one of two protocols. Cows assigned to the PG 6-day CIDR protocol (PG6d) received prostaglandin F2a (PG) on d-9, CIDR insertion and GnRH on d-6, and CIDR removal and PG on d0. Cows assigned to the 7&7 Synch protocol (7&7) were administered PG and CIDR insertion on d-14, GnRH on d-7, CIDR removal and PG on d0. For both protocols, FTAI occurred coincident with GnRH 66 h after second PG. Pregnancy was determined by transrectal ultrasonography 30-40 d following FTAI. The GLIMMIX procedure of SAS (9.4) was used to detect differences in estrus response and pregnancy success with herd included as a random variable. Estrus response (0 to 66 h) was influenced by treatment (P< 0.01; PG6d=60±5% and 7&7=74±4%), Body Condition Score (P< 0.01), cycling status (P=0.03), P4start (P< 0.01), and a P4start by treatment interaction (P< 0.001; PG6d-highP4=62±6%, PG6d-lowP4=58±6%, 7&7-highP4=84±3%, 7&7-lowP4=60±6%). Pregnancy success was influenced by estrus expression (P< 0.01; estrus=38±4% and no estrus=62±6%), and a treatment by P4start interaction (P=0.04; PG6d-highP4=58±5%, PG6d-lowP4=39±7%, 7&7-highP4=49±5%, 7&7-lowP4=55±8%) but was not influenced by treatment (P=0.45; PG6d=49±4% and 7&7=52±4%). In conclusion, effectiveness of pre-synchronization method depends on a cows' physiological status at the beginning of the protocol. The 7&7 protocol increased estrus response compared to PG6d, but there was no difference in pregnancy success. [ABSTRACT FROM AUTHOR]

Antral Follicle Count (AFC) and anti-Müllerian hormone (AMH) concentrations are reflective for ovarian reserve and have been associated with improved reproductive performance in cattle. Key events for regulation of uterine receptivity are orchestrated by progesterone. As progesterone concentrations are greater in animals with high than low AFC, we tested the hypothesis, if the resulting improved uterine environment will lead to improved conceptus elongation and endometrial response to interferon tau. For four years, 10 heifers with lowest and highest AFC, respectively, were selected from 120 heifers. Reproductive tracts and blood samples for progesterone and AMH analysis were collected after synchronization and insemination. For a recovered conceptus, length was determined, and interferon tau (IFNT) transcript abundance was analyzed. Endometrial transcript abundance of interferon-stimulated gene 15 (ISG15) and oxytocin receptor (OXTR) were analyzed. Progesterone concentrations did not differ between Low and High AFC Group (P = 0.1). A difference in conceptus length was not observed. Endometrial abundance of ISG15 did not differ between Pregnant Low and High AFC heifers. Abundance of OXTR was greater in Open Low AFC than Open High AFC heifers (P < 0.01). Interaction of AMH and Pregnancy Status was determined, with greater AMH in Pregnant than Open High AFC heifers (P < 0.05). Improved uterine environment in High vs. Low AFC heifers did not result in longer conceptuses or improved endometrial response. As the increase in OXTR transcript abundance was only detected in Low AFC heifers, reported differences in reproductive performance might be associated with earlier initiation of luteolysis., (© The Author(s) 2024. Published by Oxford University Press on behalf of Society for the Study of Reproduction.)

Presynchronization was evaluated as a method to improve estrus response before fixed-time AI (FTAI). The objective was to compare FTAI results in beef cows from two different presynchronization approaches. Blood samples were collected on Day -14 (Day 0 = CIDR removal) to determine progesterone concentration (≥1 ng/mL = high, <1 ng/mL = low). In a subset (n = 1289), an additional blood sample was collected between Day -21 and -29 to determine cyclicity (if both the Day -14 and Day -21 to -29 samples were classified as low progesterone cows were classified as noncycling). Cows (n = 1388) from 30 herds were grouped by days postpartum (DPP) and age, and randomly assigned to either of two protocols. Cows assigned to the PG 6-day CIDR & FTAI protocol (PG6d) received prostaglandin F 2α (PG) on Day -9, CIDR insertion and GnRH on Day -6, and CIDR removal and PG on Day 0. Cows assigned to the 7&7 Synch protocol (7&7) were administered PG and CIDR insertion on Day -14, GnRH on Day -7, and CIDR removal and PG on Day 0. For both protocols, FTAI occurred concurrently with GnRH 66 h after second PG. Pregnancy was determined by transrectal ultrasonography 30-40 d after FTAI. The GLIMMIX procedure of SAS was used to detect differences in estrus response and pregnancy success with herd as a random variable. Estrus response (0-66 h) was analyzed with two models, one included cyclicity and another replaced cyclicity with progesterone concentration at Day -14. In both models, cows assigned to the 7&7 protocol had greater (P < 0.01) estrus response than cows assigned to the PG6d protocol. The model including cyclicity, estrus response was impacted by the cyclicity by DPP interaction (P = 0.03), cyclicity by protocol interaction (P = 0.04), and the tendency of BCS by protocol interaction (P = 0.08). In the estrus response model that included progesterone concentration at Day -14, significant variables included the protocol by progesterone concentration at Day -14 (P = 0.01), and BCS (P < 0.01), while DPP (P = 0.08) and progesterone concentration at Day -14 (P = 0.07) were tendencies. Pregnancy success was influenced by estrual status (P < 0.01), body condition score (P = 0.04), and cycling status (P = 0.02), but was not influenced by protocol (P = 0.75; PG6d = 38 ± 5% and 7&7 = 37 ± 5%). In conclusion, effectiveness of presynchronization method depended on a cows' physiological status, and the 7&7 protocol increased estrus response compared with PG6d, but there was no difference in pregnancy success., Competing Interests: Declaration of competing interest There are no known competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Assisted reproductive technologies are used to propagate desirable genetics in a shortened timeframe. Selected females undergo ovarian stimulation with the use of follicle stimulating hormone (FSH) to increase embryo recovery for subsequent transfer programs. The FSH receptor (FSHR) c.337 C > G variant was reported to have a reduction in viable embryo numbers in an ovarian stimulation protocol. We, therefore, hypothesized that FSHR c.337 C > G would result in reduced in-vitro blastocyst development. Beef heifers were genotyped and selected based on the c.337 C > G FSHR genotype (CC, CG, GG; n = 15-16/genotype). Estrus was synchronized with a Select Synch protocol and heifers were slaughtered 5 days after induced ovulation. Anterior pituitaries, serum and reproductive tracts were collected at slaughter for analysis. Cumulus oocyte complexes (COCs) were collected and pooled within genotype for in-vitro fertilization (IVF) and subsequent blastocyst development. No differences were observed in carcass weights, anterior pituitary weights, serum progesterone, corpus lutea weight, surface follicle counts, histological follicle counts or follicular fluid estradiol concentration (P > 0.1) due to FSHR genotype. Differences were observed for ovulation rates in the GG FSHR genotype group (P < 0.01). However, cleavage and blastocyst rates were not affected due to FSHR genotype (P > 0.1), following standard IVF protocols. The FSHR variant does not influence antral follicle counts, estradiol production, or in-vitro blastocyst development in beef heifers. The GG FSHR genotype had an increased ovulation rate, which may indicate a greater potential for twinning, but research with a larger population is warranted to support this hypothesis., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to declare., (Published by Elsevier Inc.)

Nutritional changes immediately after insemination cause increased embryonic mortality, but the mechanisms controlling this are not well known. Our objective was to evaluate the impact of nutritional change on estrus expression, steroid concentrations, peripheral and uterine luminal fluid metabolites, and embryo quality in beef heifers. Heifers (n = 139) were assigned to one of two pre-artificial insemination (AI) dietary treatments: LOW (≤ 90% NEm) or HIGH (≥ 139% NEm). Heifers were on treatment for 33-36 days before AI (d0) when half of the heifers in each treatment were randomly reassigned to generate four treatments; HIGH-HIGH, HIGH-LOW, LOW-HIGH, and LOW-LOW. Heifers remained on treatments until embryo collection (d 6-8). Negative energy balance was achieved among LOW heifers as demonstrated by body weight loss and increased NEFA concentrations (P < 0.05). Pre-AI treatment influenced expression of estrus (P = 0.05; HIGH 80.4 ± 4.0% vs. LOW 69.4 ± 4.2%). Estradiol concentrations and interval to estrus were not affected by treatment (P > 0.55); however, progesterone concentrations were reduced among LOW compared to HIGH (3.57 ± 0.27, 4.64 ± 0.26 ng/mL, respectively; P = 0.004), and heifers maintained on the HIGH pre-AI diet had consistently greater concentrations of progesterone from d 0 to d 8 (P = 0.014). Pre-AI treatment influenced embryo stage (P = 0.05; HIGH 3.61 ± 0.32 vs. LOW 2.72 ± 0.30). Post-AI treatment affected embryo grade (P = 0.02; HIGH 1.78 ± 0.23 vs. LOW 2.64 ± 0.27). In summary, pre-AI nutrient restriction caused decreased expression of estrus, reduced progesterone concentrations after AI, and negatively impacted embryo development, while post-AI restriction hindered embryo quality., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Increased antral follicles are associated with greater fertility and a uterine environment that is more supportive of early embryonic development in beef heifers. Glucose is a primary energy source for embryos, and glucose concentrations are elevated in uterine luminal fluid (ULF) of pregnant heifers. We hypothesized that ULF glucose concentrations and endometrial transcript abundance for glucose transporters on d16 after insemination would be greater in heifers with increased numbers of antral follicles. Heifers classified with either increased or diminished antral follicle counts were artificially inseminated following the CO-Synch protocol (d0). On d16 after insemination, reproductive tracts of heifers were collected at an abattoir to retrieve conceptuses to determine pregnancy. Uterine luminal fluid was collected, endometrium was biopsied, total RNA was extracted and glucose transporter transcript abundances were determined. Data were analyzed using the MIXED procedure of SAS with antral follicle group, pregnancy status, and the interaction as fixed effects. Glucose concentrations in ULF were greater in heifers with increased antral follicle numbers. Glucose ULF concentrations increased in pregnant heifers. Facilitated glucose transporter member 1 (SLC2A1) transcript abundance was increased in the endometrium of pregnant heifers but was not different due to antral follicle number or the interaction. Differences in uterine concentrations of glucose associated with antral follicle number could be due to another mechanism, since glucose transporters were not different between antral follicle numbers. Therefore, heifers with increased number of antral follicles have increased energy availability in the uterus to support trophoblast proliferation and function., (Published by Elsevier B.V.)

The uterine environment must provide sufficient endocrine conditions and nutrients for pregnancy maintenance and conceptus survival. The objective of this study was to determine the effects of preovulatory estradiol and conceptus presence on uterine transcripts and uterine luminal fluid (ULF) proteins. Beef cows/heifers were synchronized and artificially inseminated (d 0). Uteri were flushed (d 16); conceptuses and endometrial biopsies were collected. Total cellular RNA was extracted from endometrium for RNA sequencing and RT-PCR validation. There were two independent ULF pools made for each of the following groups: highE2/conceptus, highE2/noconceptus, lowE2/conceptus, and lowE2/noconceptus that were analyzed using the 2D LC-MS/MS based iTRAQ method. There were 64 differentially expressed genes (DEGs) and 77 differentially expressed proteins (DEPs) in common among the highE2/conceptus vs highE2/noconceptus and lowE2/conceptus vs lowE2/noconceptus groups. In summary, the interaction between preovulatory estradiol and the conceptus induces the expression of genes, proteins, and pathways necessary for pregnancy., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The objective of this study was to evaluate the necessity of a controlled internal drug releasing device (CIDR) in a fixed-time AI resynchronization protocol as well as to compare a commercially available blood pregnancy test with transrectal ultrasonography for Day 28 pregnancy detection. Over a two-year period, beef cows and heifers from twelve herds were inseminated using the 7-day CO-Synch + CIDR protocol. On Day 21 following the first insemination, the protocol was repeated, with animals receiving either a CIDR or no CIDR. Pregnancy status (AI1) was determined on Day 28 by both transrectal ultrasonography and the IDEXX Rapid Visual Pregnancy Test. Non-pregnant animals by both methods (CIDR: n = 190 cows, n = 228 heifers; no CIDR: n = 185 cows, n = 223 heifers) received an injection of Prostaglandin F2alpha and were inseminated at the appropriate time or bred following detection of estrus. Corpora lutea (CL) number and largest follicle diameter were recorded on a subset of non-pregnant animals (CIDR: n = 66 cows, n = 46 heifers; no CIDR: n = 76 cows, n = 41 heifers) at time of pregnancy diagnosis on Day 28. Final pregnancy status was determined a minimum of 31 days following the second AI (AI2). The GLIMMIX procedure of SAS was utilized for estrus and pregnancy data; while the MIXED procedure was utilized for analyses of CL number and largest follicle diameter. There was no effect (P ≥ 0.55) of treatment on AI1 pregnancy, AI2 pregnancy, or overall pregnancy rates. The presence of a CIDR during the resynchronization increased (P < 0.001) estrus expression prior to AI2. There was an effect of treatment by age on AI2 pregnancy (P < 0.01); heifers that received a CIDR had greater AI2 pregnancy rates than heifers that did not receive a CIDR (P = 0.04), but there was no difference between cows with and without a CIDR. Treatment had no effect (P > 0.10) on embryonic loss (between the first and second pregnancy diagnosis), CL number, or follicle diameter. Although, there was a tendency for the interaction of treatment by age on follicle size (P = 0.07), with cows having larger follicles than heifers in the no CIDR group but not the CIDR group. In conclusion, use of a CIDR in this resynchronization protocol increased estrus expression, increased AI2 pregnancy for heifers, but did not improve pregnancies in cows, and did not influence overall pregnancy or embryonic loss., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Previous research has indicated that gender-sorted semen has decreased conception rates compared to conventional semen. A new method to skew the gender ratio of semen has been developed that does not use traditional sorting technology. Thus, the objective of this study was to evaluate the use of gender-ablated semen in a fixed-time AI protocol. Beef heifers and cows (n = 878) from six herds were synchronized with the 7-d CO-Synch plus CIDR protocol, and artificially inseminated (AI) after CIDR removal (cows 60-66 h; heifers 52-56 h). Estrus detection aids were applied at CIDR removal and estrus activity was determined at time of AI. Animals remained separated from bulls for at least 10 d after AI. Pregnancy success and fetal age were determined between d 28 and 70 after AI. Semen from five sires was utilized in this study, with two sires used in each herd. Sire 1 was used in all herds and the use of the second sire varied by herd (both conventional and gender-ablated semen from each sire was used in each herd). Data were analyzed using the GLIMMIX procedure in SAS and included the influence of semen type, estrus expression, semen type by estrus expression, dam age, and sire in the model. Herd was included as a random variable. Overall, conventional semen had greater conception rates compared to gender-ablated semen (P < 0.01; 67% vs 52%), and cows that had fully activated patches and partially activated patches had greater conception rates compared to animals that had not exhibited estrus (P < 0.01; 69%, 65%, and 45%). There was no semen type by estrus expression interaction (P = 0.24). Conception rates tended to be greater for conventional semen among animals that had activated patches (P = 0.06; 73% vs 65%) and partially activated patches (P = 0.06; 72% vs 59%). Conception rates were greater for conventional semen (P < 0.01; 56% vs 33%) among animals that did not exhibit estrus. There was no effect of dam age (P = 0.40) or sire (P = 0.92) on conception rates. In conclusion, Sexcel™ gender-ablated semen can successfully be used in fixed-time AI protocols among animals that exhibit estrus, but caution should be used among animals that do not exhibit estrus., Competing Interests: Declaration of competing interest Merlyn D. Sandbulte and Fabiana B. Mokry are employed by ABS Global, DeForest, WI and Genus plc, DeForest, WI, respectively. They were involved with the processing and the donation of the semen used in this study. They were not involved in the analysis or interpretation of the data., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

The ability to induce ovulation with an injection of GnRH facilitated the development of fixed-time artificial insemination (AI) protocols. However, animals that exhibit estrus prior to fixed-time AI have greater pregnancy success. Thus, the objectives of the present experiments were to determine the impact of estrus expression prior to fixed-time AI on timing of conception and to characterize the role of preovulatory estradiol in regulating changes in expression of uterine genes. In experiment 1, data were collected from 4,499 beef cows inseminated by fixed-time AI in 31 different herds. Animals that did not conceive to AI but exhibited estrus before timed-AI were more likely to conceive during cycle 1 after AI, and overall conceived earlier in the breeding season compared to animals that did not exhibit estrus. In experiment 2, beef cows were synchronized using a fixed-time AI protocol. Uterine horn biopsies and blood samples were collected on Day 0, 5, 10, or 16. Concentrations of estradiol on Day 0 did not influence expression of progesterone receptor, ER beta, or oxytocin receptor. Increased concentrations of estradiol on Day 0 increased expression of ER alpha from Days 0 to 5 of the estrous cycle. Furthermore, cows with increased concentrations of estradiol on Day 0 had increased expression of inhibin beta A, and uterine milk protein precursor. Thus, animals that do not exhibit estrus prior to fixed-time AI had decreased breeding season pregnancy success and conceived later in the breeding season, and preovulatory concentrations of estradiol likely play a major role in this establishment of pregnancy, not only directly by regulating uterine gene expression, but also indirectly throughout the subsequent estrous cycle.

The objective was to determine the effects of pregnancy status on oxylipin profiles and eicosanoid metabolizing enzymes and in corpora lutea (CL) or endometrial (caruncle; CAR and intercaruncle; IC) tissues. Angus crossed cattle were synchronized with the CO-Synch protocol and artificially inseminated (AI). Sixteen days after AI, cattle were euthanized, and reproductive tracts collected from 6 non-pregnant and 6 pregnant cows. Oxylipin profiles and concentrations of progesterone (P 4 ) were obtained from CL tissues. The activity of cytochrome P450 1A (CYP1A) and UDP-glucuronosyltransferase (UGT) enzymes were determined using specific luminogenic substrates. Data were analyzed using the MIXED procedure of SAS, and the model included pregnancy status. Corpora lutea of pregnant cattle contained greater (P < 0.05) concentrations of 9,10-DiHODE, 15,16-DiHODE, and 9,10-DiHOME. These oxylipins have been observed to increase cellular proliferation and vasodilation. Activity of CYP1A in the CL and UGT in CAR and IC was not different (P > 0.05) between pregnant and non-pregnant cattle. In the CL, activity of UGT was decreased (P < 0.05) in pregnant vs. non-pregnant cattle. The decrease in CL UGT activity during pregnancy indicates alterations in local hormone metabolism, while no differences in CL weight nor amount of P 4 in CL were different between pregnant and non-pregnant cattle. Moreover, the increase in specific concentrations of oxylipins in the CL may indicate a novel pathway of steroid and eicosanoid metabolism during maternal recognition of pregnancy., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Bos indicus females have more surface antral follicles than Bos taurus females; however, histological studies demonstrated no difference in total number of primordial follicles between these two biological types of cattle. Primordial follicle density in the ovary was less in Nelore ovaries compared to Angus ovaries, but no studies have examined the primordial follicle density in Bos indicus cross-bred females. It, therefore, was hypothesized that primordial follicle density in the ovary would decrease as percentage Bos indicus increased. Ovaries were collected from cross-bred Angus (n = 32, no Bos indicus influence), Brangus (n = 15), or Brahman (n = 9) cows and prepared for histological evaluation. There was no difference in total number of primordial follicles per ovary between breeds (P > 0.10). When numbers of primordial follicles were expressed on a per gram of ovarian tissue basis, there were fewer primordial follicles per gram of ovarian tissue in Brangus and Brahman cows than in Angus cows (P < 0.05). Brangus cows did not differ from Brahman cows in primordial follicle density (P > 0.10). Differences in primordial follicle density could indicate differences in capacity of ovarian stroma to produce factors necessary for oogonial proliferation and primordial follicle formation among breeds. Identifying these factors could improve the aprroach for culturing pre-antral follicles of cattle. Furthermore, these results explain why ultrasonographic antral follicle counts may need to be adjusted to a greater threshold to predict size of the ovarian reserve and determine ovarian reserve related reproductive traits in Bos indicus females., (Published by Elsevier B.V.)

The number of antral follicles detectable by ultrasonography in heifers is influenced by age of the dam, because daughters of primiparous cows have fewer antral follicles than daughters of mature cows. We, therefore, hypothesized that heifers with primiparous dams would have fewer primordial follicles in their ovaries than heifers born to mature (4+ y) cows. Angus heifers (n = 464) were submitted for ultrasonographic evaluation of antral follicle number at 325, 355, and 385 d of age. Ovaries were collected from a random subset of heifers (n = 79) and processed for histological evaluation to determine number of primordial follicles. A greater percentage of heifers with primiparous dams had a corpus luteum at first ultrasonographic examination; however, a greater percentage of heifers with multiparous dams had ovulated by the start of breeding (P <  0.01). Heifers with primiparous dams had fewer antral follicles detectable by ultrasonography (P <  0.01). Heifers with primparous dams had fewer surface antral follicles on their ovaries (P <  0.01), and the number of primordial follicles per histological section was less for heifers with primiparous dams (P =  0.02). These data indicate that the lesser number of antral follicles detectable by ultrasonography in heifers with primparous dams is due to less ovarian follicle reserves. Selecting replacement heifers from mature dams may result in daughters with greater fertility and reproductive longevity; however, further research is necessary to determine if interactions between size of the ovarian follicle reserve and age at puberty influence fertility and reproductive longevity in replacement heifers., (Published by Elsevier B.V.)

Previous research has indicated that multiple small doses of GnRH following CIDR removal increased circulating concentrations of estradiol. Therefore, our objective was to determine if a single small dose of GnRH (5 μg or 10 μg) at CIDR removal would impact expression of estrus and/or interval to estrus. Beef cows and heifers (n = 1620; n = 1057 cows, n = 563 heifers) were synchronized using the 7-day CO-Synch + CIDR protocol, and randomly assigned to one of three treatments (0, 5, or 10 μg of a GnRH analog at CIDR removal). Animals were inseminated following detection in estrus. Interval to estrus was calculated for each animal that exhibited estrus (INTERVAL 1). Animals that did not exhibit estrus were administered 100 μg of GnRH at the time of AI and their interval to estrus was designated at 120 h (INTERVAL 2). There was a treatment by age interaction (P = 0.05) on INTERVAL 1. Heifers treated with 5 μg of GnRH tended to have a shorter interval to estrus (P = 0.07; 47 ± 1.4 h) compared to 0 μg (50 ± 1.5 h) and did have a shorter interval compared to 10 μg (P < 0.01; 52 ± 1.5 h). There were no differences between treatments in interval to estrus among cows (P > 0.34). When animals that did not exhibit estrus by 120 h were included in the analysis there was no treatment by age interaction (P = 0.49). This is likely due to the fact that treatment (P < 0.01), but not age (P = 0.96) or treatment by age (P = 0.74) influenced expression of estrus. In addition, there tended to be a treatment by estrus interaction (P = 0.08) on pregnancy success. There was no difference in pregnancy success between treatments among animals that exhibited estrus (P > 0.30). In summary, 5 μg of GnRH at CIDR removal tended to decrease the interval to estrus and increased expression of estrus among heifers but not cows, and 10 μg of GnRH at CIDR removal did not improve estrus expression and lengthened the interval to estrus in comparison to the control., (Copyright © 2018 Elsevier Inc. All rights reserved.)