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We determined whether a newly designed AI plastic sheath with three outputs for semen deposition would reduce semen reflux into the sheath and increase pregnancy rates of beef females enrolled in estrus synchronization protocols. A total of 881 Angus and Angus crossed beef heifers (13 ± 1.5 m of age) at 7 different locations were enrolled in this study. Heifers from locations 1, 2, 4, and 5 were enrolled in the 14-day+CIDR-PG estrus synchronization protocol, and heifers from locations 3, 6, and 7 were enrolled in the 7-day CO-Synch+CIDR estrus synchronization protocol. Individual BCS were determined 2 d (locations 3, 6, and 7) and 3 d (locations 1, 2, 4, and 5) prior to AI. Within location, heifers were stratified by BCS and randomly assigned to two treatments: (1) fixed-time AI using an AI plastic sheath with three semen outputs (Tri; n = 440) or (2) fixed-time AI using an AI plastic sheath with a single semen output (Single; n = 441). After each insemination, the AI plastic sheaths were examined for signs of semen reflux into the sheath. Pregnancy data were analyzed using GLIMMIX procedure of SAS with heifers as the experimental unit, including the fixed effects of treatment, location, BCS, and random effects of sire and AI technician. Heifer BCS differed (P < 0.001) among locations but was similar (P = 0.606) between treatments (5.5 ± 0.03) and no treatment × location interaction was detected (P = 0.647). Pregnancy rate was similar (P = 0.696) between treatments (52.9 ± 0.02% and 54.4 ± 0.02%, for Single and Tri heifers, respectively). There was a location effect (P < 0.001) on pregnancy rate, ranging from 43.4% to 68.6%, and no treatment × location interaction was detected (P = 0.352). There was a difference (P < 0.001) between AI sheaths on percentage of sheaths with signs of semen reflux after insemination (13.8 vs. 4.8 ± 0.01% for Single and Tri AI sheaths, respectively). However, signs of reflux in the AI sheath were not correlated (P = 0.7225; R = 0.0001) with pregnancy outcome. We conclude that the AI plastic sheath with three semen outputs decreased the percentage of AI sheaths with signs of semen reflux but failed to increase fixed-time AI pregnancy rates of beef heifers. [ABSTRACT FROM AUTHOR]

It has been demonstrated that Faecalibacterium prausnitzii (FP) has the capacity to produce anti-inflammatory products, including production of interleukin-10 (IL-10) an immunosuppressive factor that inhibits the synthesis and bioactivity of cytokines, and increases butyrate production. Administration of FP to dairy calves during the first week of life decreased incidence of diarrhea, improved ADG, and enhanced weaning weight. The objective of this study was to evaluate the effect of FP administration at birth on growth and performanceWinter- born calves from Virginia Tech's commercial and purebred beef cattle herds were enrolled in this study. Cows previously diagnosed as pregnant were stratified by breed, BW and parity, and their calves were randomly assigned to one of two treatments: 1) oral administration at birth of FP at a concentration of 1.34 x 10^7 CFU/mL (FPS; n = 54; 39 males and 15 females); or 2) a placebo oral administration at birth of culture media containing no bacteria (CTR; n = 57; 39 males and 18 females). At birth, individual calf BW, and sex were determined. Calves were maintained with their dams until weaning as a single group, and were monitored daily for incidence of diarrhea. BW was determined monthly until weaning. The MIXED procedure of SAS was used to analyze all data, the statistical model included the fixed effects of treatment and breed, and random effects of calf sex, cow BW and parity as well as all interactions. Calf birth BW was similar (P = 0.830) between treatments (80.6 ± 1.6 kg and 81.1 ± 1.75 kg for CTR and FPS, respectively), male calves were heavier (P = 0.006) at birth compared to females, but no treatment × sex interaction was detected (P = 0.45). No calves were treated for diarrhea during the experiment. Calf ADG was similar (P = 0.34) between treatments (1.09 ± 0.02 kg and 1.13 ± 0.03 kg for CTR and FPS, respectively). However, adjusted weaning weight for 205 d tended (P = 0.08) to be greater for FPS calves (275.6 ± 3.6 kg) compared to CTR calves (268.9 ± 4.0 kg). Our results indicate that FP has the potential to improve beef calf pre-weaning performance, however further investigation is warranted. [ABSTRACT FROM AUTHOR]

Previous reports have indicated that supplementation of calcium salts of soybean oil (CSSO) to beef cows enrolled in estrus synchronization protocols resulted in increased pregnancy rates. We determined the effects of CSSO supplementation on ovulatory follicle diameter, corpus luteum (CL) volume, and concentrations of progesterone of beef cows enrolled in an estrus synchronization protocol. A total of 25 Bos taurus beef cows were stratified by BW, BCS, and parity and randomly assigned to one of the following treatments: 1) 0.1kg/day of prilled saturated fatty acids (Energy Booster, Milk Specialties, Eden Prairie, MN; CTRL; n = 12); 2) 0.1kg/day of CSSO (Essentiom, Church and Dwight Co., Inc., Princeton, NJ; TRT; n = 13). To ensure treatment consumption, all cows received an additional 0.7 kg/day of corn gluten feed mixed with the treatments. Cows were individually penned and received the treatments daily for a total of 49 days. Cows were maintained in the same pasture with ad libitum access to forage and water for the duration of the study. On d 21 cows were enrolled in the 7-d CO-Synch+CIDR estrus synchronization protocol. Briefly, on d 21 administration of 100 mg of GnRH and CIDR insertion, d 28 CIDR removal and administration of 25 mg of PGF2α, and administration of 100 mg of GnRH on d 31. Blood samples from each cow were taken on d 21, 28, 31, 32, 33, 34, 35, 36, 37, 38, 39, 46, and 49 for analysis of concentration of progesterone. Transrectal ultrasonography was used to determine diameter of the largest follicle on d 28 and CL volume on d 39. Progesterone concentration increased (P < 0.001) following ovulation synchronization, however was similar (P = 0.27) between treatments (2.73 ± 0.271 ng/mL), and no treatment × day interaction was detected (P = 0.60). Diameter of the largest follicle on d 28 was similar (P = 0.78) between treatments (17.0 ± 2.0 mm). In addition, volume of the CL on d 39 was also similar (P = 0.86) between treatments (3.68 ± 1.05 cm3). We conclude that supplementation of CSSO to beef cows enrolled in an estrus synchronization protocol did not alter ovulatory follicle diameter, CL volume and concentration of progesterone following ovulation. [ABSTRACT FROM AUTHOR]

Reproductive efficiency is a key component of sustainable dairy production, significantly influencing herd profitability. Because of the known interactions between energy status, insulin sensitivity, and the hypothalamus- pituitary-gonadal axis, volatile fatty acid dynamics are likely to influence reproductive status via downstream signaling. Altering volatile fatty acid dynamics has been minimally explored in relation to reproductive status and could be a viable strategy for improvements in this area. The objective of this study was to investigate the effect of increased propionate status on progesterone profiles in dairy heifers. Eleven Holstein heifers, 8 to 10 months of age and 550 to 800 lb, were subject to an OvSynch + CIDR procedure, then assigned to two treatments and given a continuous IV infusion of either sodium propionate (PRO; 61.6 mmol/hr; n=5) or saline (CON; n=6) at a matching infusion volume for 5 days. Daily blood samples were taken from animals for an additional 7 days after the end of the infusion. Plasma propionate concentrations increased over the first 9 hours in PRO cows. Between hour 9 and day 3, plasma propionate concentrations decreased in the PRO group until they matched levels seen in CON cows. No difference in plasma propionate concentrations were identified after day 3. There were no differences in daily plasma acetate or beta-hydroxybutyrate levels seen between treatments for any timepoints within the experimental period (P > 0.10). Plasma progesterone levels rose at a similar rate in both PRO and CON cows, however, PRO cows had the tendency to reach greater maximum progesterone levels (4.19 vs 3.73 ng/mL; P = 0.087). The results of this study indicate that although infusing propionate to dairy heifers initially increases plasma propionate levels, there appears to be a metabolic shift allowing the animal to clear the surplus propionate and return plasma concentrations to basal levels. This phenomenon warrants further investigation because it suggests ample capacity of the animal to metabolize propionate, provided ruminal fermentation can be manipulated to deliver additional quantities to the bloodstream. Further, the increased magnitude of progesterone response suggests a role for propionate, and volatile fatty acid supply and subsequent metabolism, in modulating reproductive performance. [ABSTRACT FROM AUTHOR]

Endophyte-infected tall fescue occupies most grazing lands in the Southeastern U.S. and is associated with poor growth and reproductive performance. Supplementing bicarbonate to cattle grazing endophyte-infected tall fescue was hypothesized to be a strategy to alleviate these negative performance outcomes. The objective of this study was to evaluate growth and reproductive characteristics of heifers consuming endophyte-infected tall fescue with or without sodium bicarbonate supplementation. Forty-eight heifers (8 mo; BW = 589 ± 53 kg) were blocked by BW and assigned to pens and treatments. Heifers were group-housed and fed individually using Calan gates. Treatments were arranged as a 2 × 2 factorial design with heifers receiving either high- or low-endophyte fescue seed with (E+B, E-B) or without (E+, E-) sodium bicarbonate supplementation. Heifers were fed a corn silage diet; seed and bicarbonate were supplemented at 1.5 kg/day and 0.25 kg/day, respectively. Heifer BW was recorded on sequential days at the start and end of the 84 d experiment and every 14 d. Feed intake and refusals were collected daily. The BW and DMI data were used to estimate ADG and G:F. Reproductive tract scores (RTS) were performed every 28 d via transrectal palpation and ultrasonography. Results were analyzed after the 2nd ultrasound (56 d) and at the end of the experiment. At d 56, RTS (P = 0.005) was affected by the interaction of bicarbonate supplementation and fescue seed type, and G:F (P = 0.061) and ADG (P = 0.058) tended to be affected. In general, RTS, G:F, and ADG of all other treatments were improved compared with the E+ treatment. Neither factor affected DMI at d 56 (P > 0.10). By d 84, bicarbonate supplementation tended to decrease ADG (P = 0.051) and decreased G:F (P = 0.016), and infected fescue consumption tended to decrease DMI (P = 0.060). On d 56, bicarbonate showed promise as a strategy to ameliorate the negative effects of endophyte-infected fescue consumption; however, by the end of the study, no effects of fescue seed type on ADG or G:F were observed. Short-term bicarbonate supplementation appears to be a promising strategy to eliminate negative production responses associated with endophyte-infected fescue consumption; however, additional research is needed to fully understand why this benefit was not sustained over the full experimental period and how the strategy would translate to traditional pasture systems where animals can self-select a bicarbonate supplementation level. [ABSTRACT FROM AUTHOR]

We determined the effects on pregnancy rates of delaying the time of AI of beef cows enrolled in an estrus synchronization protocol that were not detected in estrus by the time of fixedtime AI. At five locations, a total of 546 suckled beef cows were enrolled in the 7-d CO-Synch+CIDR estrus synchronization protocol. Briefly, 100 mg injection of GnRH and CIDR (controlled internal drug release device) insertion (d -10); 25 mg injection of PGF2a, CIDR removal and estrus alert patch attachment (d -3); on d 0 (approximately 66 h after CIDR removal) cows with activated estrus alert patches received AI, but no injection of GnRH (TAI; n = 295); and cows with non -activated patches were randomly assigned to receive either 100 mg injection of GnRH and AI immediately (GnRH+TAI; n = 130); or 100 mg injection of GnRH and delayed AI 8 h later (GnRH+8AI; n = 121). Pregnancy status was determined by transrectal ultrasonography between d 35 to 45. Pregnancy data were analyzed using GLIMMIX procedure of SAS with cows as the experimental unit, including the fixed effects of treatment, location, age of cow, days post-partum (DPP), BCS, and the random effects of sire and AI technician. There were no differences among treatments on BCS (5.6 ± 0.63; P = 0.579), DPP (73 ± 15 d; P = 0.906), and cow age (5.4 ± 2.6 yr; P = 0.192). A total of 295 cows (54%) had activated estrus alert patches on d 0. Overall pregnancy rates differed (P < 0.001) among locations, ranging from 30.7% to 66.9%, and no treatment × location interaction was detected (P = 0.454). Average delayed between GnRH injection and delayed AI was 7 ± 1.6 h. Pregnancy rate to fixed-time AI differed (P = 0.018) among treatments. Cows in the TAI treatment had the greatest pregnancy rate (59.1 ± 0.03%) compared to cows in GnRH+TAI (43.3 ± 0.04%) group, and GnRH+8AI (50.9 ± 0.05%) was intermediate. We conclude that suckled beef cows enrolled in the 7-d CO-Synch+CIDR estrus synchronization protocol that are detected in estrus prior to the time of AI have greater pregnancy rates compared to cows that are not detected in estrus and receive an injection of GnRH and AI at 66 h after CIDR removal. Furthermore, delaying insemination after GnRH injection failed to increase pregnancy rates of cows not detected in estrus. [ABSTRACT FROM AUTHOR]

This experiment evaluated reproductive and productive responses of beef cows receiving self-fed low-moisture blocks (LMB) enriched or not with Ca salts of soybean oil (CSSO) throughout the breeding season. Non-pregnant, suckled multiparous Angus-influenced cows were assigned to a fixed-time artificial insemination (AI) protocol (day -10 to 0) followed by natural service (day 15-70). Cows were managed in 12 groups (46 ± 4 cows/group) maintained in individual pastures, and groups received LMB enriched with 25 % (as-fed basis) of CSSO or ground corn (CON) from day - 10 to 100. Both treatments were designed to yield a daily LMB intake of 0.454 kg/cow (as-fed basis). Cows receiving CSSO had greater (P < 0.01) mean concentrations of ω-6 fatty acids in plasma samples collected on days 0 and 55. Cows receiving CSSO had greater (P = 0.05) pregnancy rate to fixed-time AI (67.2 vs. 59.3 %), whereas final pregnancy rate did not differ (P = 0.92) between treatments. Pregnancy loss was less (P = 0.03) in CSSO cows (4.50 vs. 9.04 %), which also calved earlier during the calving season (treatment × week; P = 0.04). Weaning rate tended to be greater (P = 0.09) in CSSO (84.8 vs. 79.4 %), although calf weaning age and weight did not differ (P ≥ 0.72) between treatments. Kilos of calf weaned/cow exposed was greater (P = 0.04) in CSSO cows (234 vs. 215 kg). Therefore, supplementing CSSO to beef cows via LMB during the breeding season improved their reproductive and overall productivity during a cow-calf cycle., Competing Interests: Declaration of interest Nothing to declare., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The objective of this study was to characterize plasma concentrations of pregnancy-associated glycoprotein (PAG) and progesterone (P4) as predictors of twins and pregnancy loss in Holstein cows with high-risk pregnancies. High-risk pregnancy was characterized using transrectal ultrasonography 37 d after artificial insemination (AI) based on the following criteria: small embryo size <15 mm, n = 10), slow heartbeat (<60 beats per minute, n = 11), and extra-amniotic membrane (additional amniotic membrane, n = 3). A cohort of twins (n = 41) diagnosed at d 37 post-AI was also enrolled. Each high-risk and twin pregnancy cow was paired with a cow of the same parity carrying a normal singleton at d 37 post-AI (control, n = 65). Blood samples were collected to measure PAG and P4 at d 37, 44, and 51 post-AI. Statistical analysis was performed using ANOVA, logistic regression, and receiver operator characteristic (ROC) curve with JMP software (SAS Institute Inc., Cary, NC). Pregnancy loss at d 51 post-AI was greater in high-risk pregnancies than in controls and twins (control = 1.5%; high-risk = 87.5%; twins = 12.2%). Concentration of PAG at d 37 post-AI did not differ among groups (control = 5.3 ± 0.7; high-risk = 4.8 ± 1.2; twins = 4.0 ± 0.9 ng/mL). Concentration of P4 at d 37 post-AI was greater in twins than in high-risk pregnancies and control, and lesser in high-risk pregnancies than in controls (control = 7.0 ± 0.3; high-risk = 5.9 ± 0.4; twins = 8.4 ± 0.3 ng/mL). Regression and ROC analysis for PAG at d 37 post-AI did not find a threshold to predict pregnancy loss or twins. Regression and ROC analysis for P4 at d 37 post-AI found that a threshold of 6.5 ng/mL predicted pregnancy loss with an area under the curve (AUC) of 0.64, and a threshold of 7.2 ng/mL predicted twins with AUC of 0.71. In summary, pregnancy loss and twins were predicted with only moderate accuracy by P4 concentration at d 37 post-AI, and the variability in PAG concentrations at d 37 post-AI was not sufficient to generate a threshold to predict pregnancy loss and twins in Holstein lactating cows., (Copyright © 2021 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)