As input costs increase, producers need to be mindful of management practices to maintain profit margins and it is important to understand current management practices. Therefore, the objective of this study was to investigate current beef marketing strategies and beliefs of beef producers in the state of Mississippi in 2019. This survey was distributed to cattle producers in Mississippi in the June/July issue of “Cattle Business in Mississippi” magazine with return postage. There also was a link included in the “Monday Memo” email sent to members of the Mississippi Cattlemen’s Association. The survey consisted of 22 questions that were divided into three sections: current practices, current cow-calf marketing practice, and general information. Responses from the survey were anonymous and confidential and were received via paper mail or electronic responses. Responses were stored and analyzed using Qualtrics. Data collected from this study were compared with 1999 data from a similar study conducted by Little et al. (2000). Out of 148 respondents, there was a 95% completion rate of surveys taken. Most respondents were 51 years and older with 54% of the respondents being part of the cattle industry for over 31 years. Ninety percent of respondents were members of the Mississippi Cattlemen’s Association and almost 60% were certified in Beef Quality Assurance. The majority, 122 of 148 producers, stated their cattle operation was not the primary source of income for their household. The average number of cows, bulls, stockers/yearling, replacement heifers and cattle on-feed on an operation was greater in the 2019 data compared with 1999. On average, the number of cows per operation increased from 40 to 68 animals, bulls increased from 2 to 5 animals, and replacement heifers increased from 7 to 17 animals from 1999 to 2019. There was also an average increase from 30 to76 animals of stocker/yearling and an increase from 2 to 27 animals of on-feed cattle. Most producers vaccinate (81%) and deworm (85%) according to recommendations and indicated a lack of labor and time as reasons for not implementing some common management practices such as preconditioning. Respondents mainly purchased calves directly from a producer (61%) or from special sales (59%). In 1999, over one-half of respondents purchased from an auction. When it came to selling cattle, 58% of respondents sold at auction regularly in 2019. In 1999, 73% of respondents sold at auctions. In 2019, 72% of respondents stated they did not retain ownership while in 1999 only 58% of respondents did not retain ownership. In conclusion, our results suggest there have been key changes within the cattle industry regarding herd size increases and a shift in selling and purchasing habits since 1999.

Abstract Flunixin meglumine (FM) is a COX enzyme inhibitor and prostaglandin E2 (PGE) builds the corpus luteum (CL). However, the use of FM in conjunction with PGE has not been studied. The objective of this study was to determine effects of intravenous administration of FM and intravaginal release of PGE on characteristics of the CL and concentrations of PGE and progesterone in blood. Beef cows (n = 24, divided between two replicants over time) were synchronized using the Select Synch + CIDR protocol (expected estrus = d 0). Cows were randomly assigned to one of four treatment groups in a factorial arrangement, with 6 cows in each: Control, FM, PGE, or FM+PGE. Treatments were administered from d 13 to 19 (FM 2.2 mg/kg iv every 12 hr; PGE released in osmotic pump at 0.1 mL/d). Every other day from d 0 to 26, transrectal ultrasonography with color Doppler was used to measure size and blood perfusion of CL; images were later analyzed with ImageJ. Blood samples were collected via jugular venipuncture every other day from d 13 to 26 and later analyzed for concentrations of progesterone (P4; RIA) and PGE (ELISA). Data were analyzed using the mixed procedure of SAS 9.4 with day as a repeated measure; significance was declared when P ≤ 0.05. There were no interactions between FM and PGE, thus main effects of treatments were evaluated. There were no differences (P ≥ 0.164) in size, vessel density, or blood perfusion of CL between treatment groups. There were no differences (P ≥ 0.141) in concentrations of PGE or P4 between treatment groups. However, concentrations of P4 and PGE and density of blood vessels decreased by day (P ≤ 0.05). In conclusion, treatment with FM or PGE did not influence CL characteristics nor concentrations of P4 or PGE in circulation.

Flunixin meglumine (FM) is a COX enzyme inhibitor and prostaglandin E2 (PGE) builds the corpus luteum (CL). However, the use of FM in conjunction with PGE has not been studied. The objective of this study was to determine effects of intravenous administration of FM and intravaginal release of PGE on characteristics of the CL and concentrations of PGE and progesterone in blood. Beef cows (n = 24, divided between two replicants over time) were synchronized using the Select Synch + CIDR protocol (expected estrus = d 0). Cows were randomly assigned to one of four treatment groups in a factorial arrangement, with 6 cows in each: Control, FM, PGE, or FM+PGE. Treatments were administered from d 13 to 19 (FM 2.2 mg/kg iv every 12 hr; PGE released in osmotic pump at 0.1 mL/d). Every other day from d 0 to 26, transrectal ultrasonography with color Doppler was used to measure size and blood perfusion of CL; images were later analyzed with ImageJ. Blood samples were collected via jugular venipuncture every other day from d 13 to 26 and later analyzed for concentrations of progesterone (P4; RIA) and PGE (ELISA). Data were analyzed using the mixed procedure of SAS 9.4 with day as a repeated measure; significance was declared when P ≤ 0.05. There were no interactions between FM and PGE, thus main effects of treatments were evaluated. There were no differences (P ≥ 0.164) in size, vessel density, or blood perfusion of CL between treatment groups. There were no differences (P ≥ 0.141) in concentrations of PGE or P4 between treatment groups. However, concentrations of P4 and PGE and density of blood vessels decreased by day (P ≤ 0.05). In conclusion, treatment with FM or PGE did not influence CL characteristics nor concentrations of P4 or PGE in circulation.

Objectives were to evaluate characteristics of corpora lutea (CL) and concentrations of progesterone (P4) in beef recipient cows stimulated with follicle stimulating hormone (FSH) prior to embryo transfer. Forty suckled beef cows received the CO-Synch+CIDR protocol and were randomly assigned to one of two treatments: 1) exogenous FSH (FSH; 1.0 mL im 2x/d on d -4 and -3, 0.5 mL 2x/d on d -2 and -1) or 2) no treatment (CON). Estrous behavior was observed for 48 hr; d 0 = expected estrus. Frozen-thawed embryos were transferred (d 7) into the 36 females observed in estrus. Transrectal ultrasonography was used to measure number of CL and size of the largest CL, blood perfusion of luteal tissue, and pregnancy (d 35). Ultrasonography and blood samples were collected on d 7, 14, 21, and 28. Data were analyzed using repeated measures of ANOVA with significance declared at P ≤ 0.05. LSMeans and SEM are presented. On d 21 and 28, cows in the FSH group had decreased (P < 0.05) size of the largest CL compared with CON (d 21 = 1.81±0.309 vs 3.20±0.293 cm2 and d 28 = 1.88±0.332 vs 2.84±0.322 cm2). Area of blood perfusion was similar between FSH and CON groups (P > 0.05), but on d 21 and 28 it was greater in pregnant cows compared with non-pregnant cows (9.78±2.109 vs 22.43±1.995 and 4.42±2.607 vs 26.38±2.533, P < 0.0001). On d 7, 14, and 21, FSH group had greater concentrations of P4 and number of CL (P ≤ 0.05). Additionally, on d 28, concentrations of P4 and number of CL were greater in FSH-pregnant cows compared to all others (P ≤ 0.05). In conclusion, FSH decreased size of the largest CL but increased number of CL and P4 on most days; it did not affect blood perfusion.

Objectives of these two experiments were to determine if exogenous estradiol benzoate (EB) affects follicular, luteal, and uterine hemodynamics. In both experiments, 77 estrous-synchronized beef cows were assigned to one of two treatments: 1) Control (CON) or, 2) an injection of 1 mg EB the day before expected estrus (Day 0; Experiment 1) or on the day of estrus (Day 1; Experiment 2). There was transfer of an embryo (Day 7) into cows that expressed estrus. In Experiment 1, estradiol concentrations in circulation at Day 0 were greater in EB-treated cows (P = 0.003); however, concentrations of progesterone were only greater (P = 0.03) at Day 21 in cows of the EB-treated compared to those in the CON group. The follicular and luteal blood perfusion was similar, however, treatment with EB resulted in a greater uterine blood perfusion. In Experiment 2, treatment with EB did not affect size or blood perfusion of the corpus luteum (CL) on Day 7, 14, and 21. Only on Day 21, however, did pregnant cows have a larger CL than non-pregnant cows (P = 0.02). Blood perfusion to the CL was greater (P < 0.05) in all cows on Day 21 compared to 7 or 14 and those determined to be pregnant on Day 35 tended (P = 0.06) to have greater CL blood perfusion only on Day 21 compared to non-pregnant cows. In conclusion, EB treatment resulted in a greater blood perfusion of the uterus, and only affected the CL on Day 21 in Experiment 2.

The aim of this study was to evaluate the effects of pegbovigrastim injection (Imrestor, Elanco Animal Health, Greenfield, IN) on production parameters and postpartum disease occurrence (retained placenta, metritis, displaced abomasum, and clinical mastitis) in dairy cows. Study cows (n = 270) were blocked by parity group (multiparous or primiparous) and randomly assigned to control (CON, n = 144) or pegbovigrastim treatment (IMR, n = 126). Ten ± 4 days before expected calving and again at calving, IMR cows received 2.7 mL of Imrestor and CON cows received 2.7 mL of 0.9 % saline. Milk yield, fat, protein, lactose, solids nonfat (SNF) percent, and somatic cell count (SCC), body condition, hygiene, and lameness were evaluated weekly. Animals were evaluated for metritis twice weekly through rectal temperature, palpation, and uterine discharge evaluation until 30 days in milk. Farm personnel recorded other postpartum diseases. The MIXED procedure of SAS was used to evaluate milk composition and milk yields were analyzed as repeated measures in time with block, treatment, calving month, and lactation week included in mixed models. The GLIMMIX procedure was used to evaluate mastitis and metritis occurrence. Variables entered a model if P ≤ 0.10 when screened individually. Variables with P ≤ 0.10 were kept in the final model. Milk yield, fat, protein, lactose, SNF, and log of SCC were not significantly affected by treatment. Clinical mastitis occurrence did not differ between treatments, but only 17 cases were detected. Compared to CON, IMR treated cows had increased clinical metritis incidence, and were 2.46 times more likely to develop the disease. No difference was observed on puerperal metritis ocurrence. Cows given pegbovigrastim injections had increased odds of developing clinical signs of metritis, but no negative effects on milk production or composition were observed.

Abstract Ovulation prompted by exogenous GnRH may cause the release of sub-mature oocytes and lead to decreased pregnancy rates. Inclusion of estradiol benzoate (EB) has improved pregnancy rates. The objective was to determine if EB affects blood perfusion of follicles, CL, or uterus, concentrations of estradiol, or incidence of standing estrus. Forty-seven suckled beef cows were synchronized (GnRH+CIDR on d -9, PGF2a+CIDR removal on d -2, expected estrus=d 0). On d -1, 24 of 47 cows received an injection of EB (1mg/2mL) while the other 23 remained as a control group. Ovaries were evaluated via Doppler ultrasonography on d -1, 0, 6, 14, and 21. A laser Doppler probe was used to measure blood perfusion of the uterus on d -1, 0, and 6. Only cows that exhibited estrus (n = 29) were evaluated on d 14 and 21. Images were analyzed via ImageJ software to determine mean area of perfusion. Blood samples were collected on d -1 and 0 and analyzed for concentrations of estradiol using RIA. Using SAS, MIXED and FREQ were used to determine the influence of treatment on blood perfusion and estradiol, and incidence of standing estrus, respectively. Treatment with EB increased (P < 0.001) the number of cows exhibiting standing estrus compared to control (21/24 vs 8/23, respectively). Treatment of EB did not (P > 0.10) alter blood perfusion of the follicles or uterus on any day or perfusion of the CL on d 6. However, EB increased (P < 0.036) the size of the CL on d 14 (25.06±1.7 vs 6.06±3.7) and tended (P < 0.097) to increase the size of the CL on d 21. Treatment of EB increased (P < 0.003) concentrations of estradiol on d 0 compared to control (21.35±4.49 vs 9.44±4.61 pg/mL). In conclusion, treatment with EB may play a role in changing the CL after ovulation.

The objective of this experiment was to evaluate effects of supplemental progesterone immediately following transfer of frozen-thawed, IVP embryos on P/ET. Holstein heifers (n = 452), allocated to nine transfer groups over time, were assigned to be embryo recipients in a completely randomized study from December 2016 to April 2017. All heifers were randomly assigned to one of two treatments: 1) control (CON; n = 212) with no further treatment, or 2) received a CIDR insert containing progesterone for 12 d, beginning on the day of transfer (D 7) and removed 12 d later on Day 19 (CIDR; n = 228). A subset of heifers were subjected to blood sampling on Day 7 (ET) and Day 19 (CIDR removal) to determine circulating concentrations of progesterone. Pregnancy was initially determined using a serum assay for pregnancy specific protein-B at approximately Day 40 after ET and confirmed a month later using trans-rectal ultrasonography. Overall, P/ET did not differ (P =  0.941) between treatment groups. At the initial pregnancy determination, P/ET differed (P =  0.007) among transfer groups. Concentrations of progesterone tended to be less (P =  0.064) in heifers in the CON group compared to heifers treated with the CIDR (3.6 ± 0.27 compared with 4.4 ± 0.27 ng/mL), and differed between transfer groups (P <  0.001) and days post-estrus (P =  0.019) of the recipients. In summary, while treatment with supplemental progesterone at the time of transfer of IVP embryos using a CIDR increased circulating progesterone, there was no influence on P/ET.

Theoretical support exists for an exaggerated male structure to serve as both a weapon for intrasexual competition and as an ornament to signal quality and promote female choice. However, there is little, if any, evidence to support this theory in male-male competition breeding systems. Using white-tailed deer, Odocoileus virginianus, as a model species, we manipulated antler size on males while controlling for body size and age and allowed 25 oestrous females the opportunity to choose between pairs of segregated males with either large or small antlers. By segregating males, we were able to remove any intrasexual male competition and isolate the effects of female choice. Using various behavioural indications of female choice, we demonstrate that females prefer males with large antlers to those with small antlers. Because antler size is heritable in deer, this female preference for larger antlers may be adaptive by increasing the reproductive success of her male offspring. Our unique antler manipulation study supports the armament-ornament model where male weapons can simultaneously serve as ornaments to females and weapons in male-male competition breeding systems. (c) 2018 The Author(s). Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour. This is an open access article under the CC BY-NC-ND license.

Pregnancy rates after the transfer of frozen-thawed, in vitro produced (IVP) embryos are less than ideal. The objective of this study was to determine whether the addition a controlled internal drug release (CIDR) device at the time of transfer of IVP embryos influenced pregnancy rates of dairy heifers. A total of 439 Holstein heifers (479 ± 33 d of age) were included in this study. Estrous cycles of heifers were synchronized and those detected in estrus with a viable corpus luteum each received a frozen-thawed IVP embryo 7.1 ± 0.47 d after detected estrus (d 0). At the time of transfer, heifers were stratified by the donor flush group of the embryo they received, and then randomly assigned to 1 of 2 treatment groups: 1) received no supplementation (control; n = 211), or 2) received supplemental progesterone via a CIDR device from d 7 (immediately after transfer) until d 19 post-estrus (CIDR; n = 228). Transrectal ultrasonography and rectal palpation were performed at approximately d 30 and d 60 post-estrus, respectively, to determine pregnancy status. Developmental stage, grade, and parentage of all embryos were recorded. Data were analyzed using the GLIMMIX procedure of SAS; means are presented. Overall pregnancy rates were 27.5% on d 30 but were reduced by d 60 to 23.3%. Supplementation of progesterone did not affect pregnancy rates on either d 30 (P = 0.467; 26.5 vs 28.1%, for control and CIDR, respectively), or d 60 (P = 0.417; 24.9 vs 21.5%, for control and CIDR, respectively). Embryo parentage, grade or developmental stage or BCS of recipient heifers did not influence (P ≥ 0.105) pregnancy rates. In conclusion, supplemental progesterone via a CIDR device did not alter pregnancy rates after the transfer of IVP embryos. Further research is necessary to elucidate mechanisms to increase the viability of IVP embryos.

It is expected that grazing animals take more steps per day than those housed in free stall, confinement barns. The aim of this study was to determine if additional exercise in grazing, lactating dairy cows affected milk production, milk quality, and uterine artery blood flow during late gestation. On d 180 of their gestation, 17 (all conceived on 1 of 2 dates within 2 wk and averaged 326 DIM) Holstein cows in a grazing production system were randomly assigned to 1 of 2 treatment groups: an exercise group (WALK; n = 9) which was walked an additional 5.6 km per d and a control group (CON; n = 8) which was not walked more than normal. Cows were fitted with pedometers to record steps; data were collected daily. All animals were housed together on ryegrass pasture with a concentrate supplement. All animals were milked twice daily until the dry off period (d 223 of gestation), milk yield was recorded at each milking, and milk samples (morning and afternoon) were collected on d 180 and 210 of gestation to evaluate milk composition. Ultrasound exams were conducted on d 180, 210, and 240 of gestation to measure heart rate and uterine artery blood flow. The MIXED procedure of SAS (SAS Institute Inc., Cary, NC) was used. Least-square means and pooled standard errors are reported. The number of steps taken were greater (P ≤ 0.0001) between cows in the WALK group (7,212 ± 208 steps per d) compared to the CON group (5,637 ± 221 steps per d). The number of steps also differed (P < 0.0001) between d 210 and d 240 of gestation (7,317 ± 166 and 5,532 ± 166 steps per d, respectively). Treatment did not affect (P > 0.05) heart rate or total uterine artery blood flow. Heart rate was greater (P < 0.0001) in cows at d 210 of gestation (89.6 ± 1.61 beats per min) compared to d 240 (73.4 ± 1.61 beats per min), although total blood flow did not change (P = 0.31) between those time points in gestation. Milk yield as well as concentrations of fat, protein, and lactose were not different (P > 0.05) between treatments. Somatic cell counts and milk urea nitrogen did not differ (P > 0.05) between treatments. In conclusion, added exercise during late gestation did not impact cardiac or milk measurements in this study.

The objectives of this experiment were to determine the effects of follicular wave (first or second) on diameter of the dominant follicle, concentrations of progesterone and estradiol and the hepatic enzymes that inactivate them, thickness of the endometrium, and pregnancy rates to AI. Beef heifers ( = 101) and cows ( = 106) were randomly assigned to 1 of 2 treatments: insemination to the first follicular wave (FFW) or insemination to the second follicular wave (SFW). Estrous cycles of females were synchronized to ensure appropriate timing for the treatments. The MIXED procedure of SAS was used for analysis. A similar proportion of females in each treatment responded to presynchronization; however, females in the FFW group ovulated in response to the first injection of GnRH of the CO-Synch protocol more frequently. Only females ( = 94) that properly responded to ovulation synchronization were included in further analyses. Cows in the FFW group tended ( 0.06) to have larger ovulatory follicles 36 h post-PGF of the CO-Synch protocol compared to cows in the SFW group (14.22 ± 0.42 and 11.83 ± 0.49, respectively), whereas heifers were similar between treatment groups. Three d prior to AI, circulating concentrations of progesterone were lesser ( 0.01) in females in the FFW (3.63 ± 0.80 ng/mL) than in the SFW (7.12 ± 0.83 ng/mL), whereas concentrations of estradiol tended ( 0.08) to be greater in those in the FFW (82.72 ± 6.48 pg/mL) than in the SFW (65.55 ± 6.74 pg/mL). Concentrations of cytochrome P450 1A in the liver were lesser ( 0.01) in females in the FFW than those in the SFW (0.68 ± 0.08 vs. 0.96 ± 0.06, respectively). Endometrial thicknesses were similar between treatments but were thicker ( < 0.0001) in cows (9.73 ± 0.24 mm) than heifers (7.22 ± 0.26 mm). When considering all females or only those that were properly presynchronized, pregnancy rates were similar between treatments. However, when evaluating females that ovulated to the assigned follicular wave, there was a treatment by parity interaction ( = 0.04) with heifers in the FFW having a lesser pregnancy rate (25.9%) than heifers in the SFW (72.0%) while cows in both treatment groups were intermediate (45.4% in FFW and 50.0% in SFW). The differences in concentrations of steroids between treatment groups may affect fertility of heifers; however, additional research is necessary.

Developing a research tool that is low cost, easy to install, and can be implemented in group-housed animals is important to quantify parameters needed to promptly assess animal health and well-being. However, a practical and cost-effective solution for monitoring large numbers of animals in a production setting has not been developed. The objectives of this study were to (1) develop a self-contained and easily deployed continuous tympanic temperature logging (CTTL) probe capable of recording and storing tympanic temperature (T-T) data from group-housed beef cattle, (2) determine the minimum sampling interval needed to measure T-T in beef cattle, and (3) quantify the temperature differences among the ears (left and right) and vagina (TV). A two-part device was developed consisting of a temperature logger housed in a molded foam probe. The CTTL probe can be effectively used to measure T-T in both the left and right ears of group-housed animals. The CTTL is cheaper, faster, and easier to install and remove when compared to past methods. Recovery rate was greatly affected by cattle behavior, weather, duration of collection, and installer, but a recovery rate of >= 75% should be considered successful and <= 50% unsatisfactory. When planning research trials, increasing the number of required animals would compensate for a few dislodged temperature loggers. Periodogram analysis determined that a minimum effective sampling interval of 2.5 min (lower than in past studies) was needed to capture the dynamic nature of T-T in field conditions. Mean temperatures were different (p < 0.0001): 39.3 degrees C, 38.5 degrees C, and 38.4 degrees C for TV and T-T in the right and left ears, respectively. The mean temperature difference between the ears (left-right = -0.10 degrees C) was smaller than the mean difference between the vagina and each ear (vagina-left ear = -0.92 degrees C; vagina-right ear = 0.83 degrees C). The variability in the temperature profiles both within and between animals presents difficulty in characterizing, modeling, and subsequent prediction of thermal status using mean values. Future research should be directed toward characterizing T-T profiles of beef cattle using signal analysis for different phenotypes and growth stages.

The refinement of current and development of new technologies aimed at increasing the productivity of resources while minimizing the environmental impact will be critical to meet the global food demand in the near future. During the past 50 yr, assisted reproductive technologies have been developed and refined to increase the prolificacy and quality of calves from beef females. Artificial insemination, estrus synchronization and fixed-time AI, semen and embryo cryopreservation, multiple ovulation and embryo transfer, in vitro fertilization, sex determination of sperm or embryos, and nuclear transfer are technologies that are used to enhance the production efficiency of beef systems. Development and implementation of these technologies are responsible for significant changes to world production of beef. Sales of beef semen for AI increased from 3.3 to 13.0 million units between 1993 and 2010 in Brazil, whereas that in the United States has increased from 2.9 to 4.4 million units during the same period. This increase is likely a result of the development of practical fixed-time AI systems that have allowed beef producers the opportunity to eliminate detection of estrus in their AI programs with a high degree of success. Similarly, the quantity of in vivo–produced embryos transferred worldwide has increased from 361,000 in 1997 to 506,000 in 2012. In addition, during the last 15 yr the transfer of in vitro–produced embryos has increased more than 300%. Incorporating applied reproductive technologies continues to effect beef cattle production systems by providing producers opportunities to enhance genetics, reduce transfer of disease, advance fertility, and ultimately increase offspring value. Improvements in fertility and technology, reductions in cost, and improvements in ease of application will ensure that more cattle producers will adopt applied reproductive technologies in future years. However, incorporation of applied reproductive technologies into production systems will vary worldwide depending on cattle markets, infrastructure, production systems, and climate.

The aim of this study was to determine if fescue toxicosis altered blood perfusion in the corpus luteum (CL) and peripheral concentrations of progesterone in cattle. The estrous cycles of 36 nonpregnant Angus or Charolais cows were synchronized in 2 replicates using the CO-Synch+CIDR protocol. Seven days after initiation of the protocol, cows were assigned (d 0) to 1 of 2 dietary treatments: 2.5 kg of 1) Kentucky-31 endophyte-infected (KY31; = 14) or 2) MaxQ novel endophyte (MaxQ; = 12) tall fescue seed. On d 7, ovaries were examined using ultrasonography, and only cows that had 1 CL present remained on the study ( = 26). Images of blood perfusion of CL, blood samples, rectal temperatures, and blood pressure of tails were collected on d 10, 13, 15, and 18. Images of CL blood perfusion were analyzed using ImageJ software for pixel density, and scored visually (0 to 9 with 0 = no perfusion, 9 = complete perfusion) by 2 independent technicians. The MIXED procedure of SAS was used with day as a repeated measure. Least squares means and SEM are reported. Cows receiving KY31 had greater rectal temperatures ( 0.003; 38.76 ± 0.08°C) than those receiving MaxQ (38.44 ± 0.08°C), providing evidence that the cows treated with KY31 were influenced by fescue toxicosis. Pulse pressure and mean arterial pressure were decreased ( < 0.01) in cows receiving KY31 (55.26 ± 2.81 and 80.06 ± 2.72 mmHg, respectively) than MaxQ (66.58 ± 3.03 and 91.38 ± 2.93 mmHg, respectively). Concentrations of progesterone were similar ( = 0.54) between cows receiving KY31 (6.04 ± 0.53 ng/mL) or MaxQ (6.36 ± 0.63 ng/mL). Pixel densities ( = 0.14) and visual perfusion scores were similar ( = 0.11) between cows receiving KY31 (1477.20 ± 655.62 pixels and 2.23 ± 0.34, respectively) or MaxQ (2934.70 ± 718.20 pixels and 3.00 ± 0.36, respectively). Mean CL volume was similar ( 0.95) between treatments. In conclusion, blood perfusion of CL or peripheral concentrations of progesterone were not altered at the onset of fescue toxicosis in this short-term study, indicating that a decrease in blood perfusion of the CL may not be a primary mechanism involved in decreased reproductive efficiency of cattle during fescue toxicosis.

A multilocation study examined pregnancy risk (PR) after delaying AI in suckled beef cows from 60 to 75 h when estrus had not been detected by 60 h in response to a 7-d CO-Synch + progesterone insert (CIDR) timed AI (TAI) program (d -7: CIDR insert concurrent with an injection of GnRH; d 0: PGF injection and removal of CIDR insert; and GnRH injection at TAI [60 or 75 h after CIDR removal]). A total of 1,611 suckled beef cows at 15 locations in 9 states (CO, IL, KS, MN, MS, MT, ND, SD, and VA) were enrolled. Before applying the fixed-time AI program, BCS was assessed, and blood samples were collected. Estrus was defined to have occurred when an estrus detection patch was >50% colored (activated). Pregnancy was determined 35 d after AI via transrectal ultrasound. Cows ( = 746) detected in estrus by 60 h (46.3%) after CIDR removal were inseminated and treated with GnRH at AI (Control). Remaining nonestrous cows were allocated within location to 3 treatments on the basis of parity and days postpartum: 1) GnRH injection and AI at 60 h (early-early = EE; = 292), 2) GnRH injection at 60 h and AI at 75 h (early-delayed = ED; = 282), or 3) GnRH injection and AI at 75 h (delayed-delayed = DD; = 291). Control cows had a greater ( < 0.01) PR (64.2%) than other treatments (EE = 41.7%, ED = 52.8%, DD = 50.0%). Use of estrus detection patches to delay AI in cows not in estrus by 60 h after CIDR insert removal (ED and DD treatments) increased ( < 0.05) PR to TAI when compared with cows in the EE treatment. More ( < 0.001) cows that showed estrus by 60 h conceived to AI at 60 h than those not showing estrus (64.2% vs. 48.1%). Approximately half (49.2%) of the cows not in estrus by 60 h had activated patches by 75 h, resulting in a greater ( < 0.05) PR than their nonestrous herd mates in the EE (46.1% vs. 34.5%), ED (64.2% vs. 39.2%), and DD (64.8% vs. 31.5%) treatments, respectively. Overall, cows showing estrus by 75 h (72.7%) had greater ( < 0.001) PR to AI (61.3% vs. 37.9%) than cows not showing estrus. Use of estrus detection patches to allow for a delayed AI in cows not in estrus by 60 h after removal of the CIDR insert improved PR to TAI by optimizing the timing of the AI in those cows.

Our objective was to assess the effects of progesterone before initiating an estrus- or ovulation-synchronization program in addition to the influence of parity, BCS, and days postpartum on resulting pregnancy rates per AI. Experimental data were combined from 73 herd-year studies consisting of more than 8,500 suckled beef cows exposed to variants of the CO-Synch program. Blood was harvested from samples collected at 10 and 0 d before the onset of CO-Synch, and progesterone concentrations of the samples were determined. The progesterone environment preceding synchronization was assessed in 3 ways on the basis of progesterone concentrations measured in the 2 defined blood samples. All binomial logistic regression models used procedure GLIMMIX in SAS and included the fixed effects of program duration, inclusion of progesterone via an intravaginal insert, parity, days postpartum at AI, BCS, and appropriate interactions. In addition, model 1 included 3 categories of progesterone concentrations (low [<1 ng/mL], medium [1.00 to 3.99 ng/mL], and high [≥4.00 ng/mL] concentrations) at 10 and 0 d before synchronization and their interaction. Model 2 included 4 categories defining the stage of the estrous cycle (late diestrus, early diestrus, and proestrus-estrus-metestrus) or anestrus, at which cows started the synchronization program. Model 3 defined cows as cycling or noncycling at the onset of the program. Significant effects of progesterone supplementation, which hormone was used to initiate the timed AI program, parity, BCS, days postpartum, and progesterone status assessed in 3 ways were consistent in nearly all models. Progesterone status at the onset of synchronization was not important to pregnancy outcomes in multiparous cows, whereas pregnancy rate per AI was suppressed in primiparous cows that began in a low-progesterone environment (proestrus, estrus, metestrus, or anestrus). A significant 3-way interaction of parity, BCS, and days postpartum in 2 models reinforced the importance of these factors to AI pregnancy outcomes. Ancillary analyses identified the significant effects of cycling status and BCS as well as days postpartum on luteolytic response to PGF(2α). Pregnancy loss of 2.7% to 4.2% was detected to occur between a positive pregnancy diagnosis at 35 d post-AI and later stages of pregnancy. We concluded that progesterone status at the onset of the synchronization program is critical to pregnancy outcomes in primiparous but not multiparous cows.

Two experiments were conducted to determine the effect of administering PGF at the initiation of the 7-d CO-Synch+controlled internal drug release (CIDR) fixed-timed AI (TAI) protocol on pregnancy rates of suckled beef cows and replacement heifers. Within location, cows were stratified by days postpartum (DPP), BCS, and parity (Exp. 1; = 1,551) and heifers were stratified by BCS (Exp. 2; = 999) and randomly assigned to 1 of 2 treatments: 1) CO-Synch+CIDR (100-μg injection of GnRH at CIDR insertion [d -10] with a 25-mg injection of PGF at CIDR removal [d -3] followed by injection of GnRH and TAI on d 0) or 2) PG-CO-Synch+CIDR (a 25-mg injection of PGF on d -10 of the CO-Synch+CIDR protocol). Follicle diameter and corpus luteum (CL) development were assessed on d -10 and -3, and pregnancy status was determined on d 30 to 35. Blood was collected on d -20, -10, -3, and 0 relative to TAI to determine concentrations of progesterone (P4). In Exp. 1, TAI pregnancy rates did not differ ( = 0.667) between treatments and were affected by BCS ( = 0.003) and DPP ( = 0.006). Concentrations of P4 were greater ( < 0.0001) on d -3 for CO-Synch+CIDR than for PG-CO-Synch+CIDR (4.1 ± 0.2 and 3.4 ± 0.2 ng/mL, respectively). Follicle diameter on d -3 differed ( = 0.05) between PG-CO-Synch+CIDR (13.4 ± 0.3 mm) and CO-Synch+CIDR (12.5 ± 0.3 mm) treatments. Cows with P4 > 2.5 ng/mL on d -10 had greater ( = 0.024) pregnancy rate to TAI (56.5%) compared with cows with 2.5 ng/mL < P4 > 1 (43.0%), whereas cows with P4 < 1 ng/mL were intermediate (51.6%). Cows with a CL on d -10 had greater ( = 0.012) pregnancy rates to TAI than cows without a CL (66.3 vs. 39.4%, respectively). In Exp. 2, TAI pregnancy rates did not differ ( = 0.316) between treatments. Concentrations of P4 differed ( < 0.0001) on d -3 with greater concentrations of P4 for CO-Synch+CIDR than for PG-CO-Synch+CIDR (3.75 ± 0.20 ng/mL and 3.60 ± 0.21 ng/mL, respectively). Follicle diameter was similar ( = 0.749) between treatments on d -10 and -3. Regardless of treatment, cyclic status tended ( = 0.062) to improve pregnancy rates to TAI (55 vs. 45%, for cycling and noncycling heifers, respectively). We concluded that addition of PGF to the 7-d CO-Synch+CIDR protocol decreased concentrations of P4 in cows and heifers and increased follicle diameter at CIDR removal in cows but failed to increase TAI pregnancy rates.

School of Agricultural Sciences and Veterinary Medicine, Pontifical Catholic University, Ponce, PR Department of Animal Sciences, North Dakota State University; Fargo, ND Department of Animal and Dairy Sciences, Mississippi State University; Starkville, MS Division of Animal Science, University of Missouri; Columbia, MO Department of Animal and Range Sciences, South Dakota State University; Brookings, SD University of Nebraska, West Central Research and Extension Center; North Platte, NE Dixon Springs Agricultural Center, University of Illinois; Ubana, IL Department of Animal Sciences and Industry, Kansas State University. Manhattan, KS Effects of Administration of Prostaglandin F2α at Initiation of the 7-d COSynch+CIDR Ovulation Synchronization Protocol for Suckled Beef Cows and Replacement Beef Heifers

Anti-Müllerian hormone (AMH) has been correlated with phenotypic indicators of fertility. However, the effects of exogenous hormones used during estrus synchronization on AMH have not been evaluated. Therefore, the objective of this experiment was to determine whether concentrations of AMH at estrus are similar between a synchronized compared with a natural estrous cycle. Nulliparous dairy and beef heifers (n = 68) were synchronized with the Select Synch + controlled internal drug release (CIDR) protocol (GnRH + CIDR-7 d-CIDR removal + PG). Heifers were observed for expression of estrus every 6 h until 84 h after the injection of PG. Visual detection of the subsequent estrus, considered natural estrus, occurred every 6 h from day 16 to 24 after synchronized estrus. At the time of standing estrus, ovarian structures in heifers were evaluated by transrectal ultrasonography. Blood samples were collected at estrus for analysis of concentrations of AMH during the synchronized and natural estrous cycles. The GLM and CORR procedures of SAS were used to analyze data. Concentrations of AMH between natural and synchronized estrus were positively correlated (r = 0.67; P < 0.001). Mean concentration of AMH did not differ (P > 0.05) between the natural (0.0543 ± 0.0076 ng/mL) or synchronized (0.0428 ± 0.0076 ng/mL) estrous cycles. In conclusion, concentrations of AMH were similar between natural and synchronized estrous cycles. Concentrations of AMH in natural and synchronized estrous cycles were highly correlated within individual heifers and varied among heifers with beef heifers having increased (P < 0.05) concentrations of AMH compared with dairy heifers (0.0638 ± 0.01 and 0.0402 ± 0.01 ng/mL, respectively).