The objective of this study was to evaluate the use of luteal color doppler ultrasonography (CD) and plasma concentrations of pregnancy associated glycoproteins (PAG) for early pregnancy diagnosis in Bos taurus beef cows. Additionally, CD and PAG were evaluated as potential predictors of late embryonic/early fetal mortality (LEM). Postpartum beef cows (n = 212) were exposed to estrus synchronization followed by fixed-time artificial insemination (day 0). On days 20 and 22, B-mode and CD ultrasonography were performed to evaluate corpus luteum (CL) morphometries and blood perfusion. Moreover, blood samples were collected on days 25 and 29 to quantify circulating concentrations of PAG. Conventional ultrasonography on days 29 and 100 was utilized as the gold-standard method for pregnancy diagnosis. Cows that experienced pregnancy loss between days 29 and 100 were classified as LEM. Pregnant cows had larger and more vascularized CL compared with non-pregnant cows on days 20 and 22 (P < 0.001 for all response variables). Accuracy for CD on days 20 and 22 were 87 and 92%, respectively. Accuracy for PAG on days 25 and 29 were 84 and 99%, respectively. No false negative results were observed for CD on both days 20 and 22; however, there were 7.1% false negative results for PAG on day 25. Cows that experienced LEM had decreased (P = 0.04) circulating PAG on day 29 of gestation compared with cows that maintained pregnancy; however, there were no differences in luteal blood perfusion on days 20 and 22 (P ≥ 0.53) or circulating PAG on day 25 (P = 0.46) between LEM cows and cows that maintained pregnancy. Sensitivity and specificity of PAG on day 29 as predictors of LEM were 83 and 77%, respectively. In conclusion, CD resulted in accurate pregnancy diagnosis in Bos taurus beef cows on both days 20 and 22 of gestation while having no false negative results. Circulating concentrations of PAG were decreased in cows that experienced LEM; however, further research is required to utilize PAG as a predictor of late embryonic mortality commercially.
The objective of this study was to evaluate the use of corpus luteum (CL) color doppler ultrasonography (CD) for early pregnancy diagnosis in Bos taurus beef replacement heifers. Beef heifers (n = 183) from two locations were exposed to a 7-d CO-Synch + CIDR protocol followed by fixed-time artificial insemination (day 0). On days 20 and 22, B-mode and CD ultrasonography were performed to evaluate CL morphometries and blood perfusion, respectively. Heifers were considered non-pregnant when CL area was < 20 mm2 or estimated luteal blood perfusion was ≤ 25%. Conventional ultrasonography on day 29 was utilized to determine pregnancy status and considered the gold standard method for pregnancy diagnosis. Pregnant heifers had greater CL diameter, CL area, and CL volume when compared to non-pregnant heifers on days 20 and 22 (P < 0.001). Additionally, percentage of central, peripheral, and total luteal blood perfusion, as well as the respective blood perfusion scores were greater (P < 0.001) in pregnant compared with non-pregnant heifers on both day 20 and 22. Sensitivity, specificity, positive predicted value (PPV), negative predicted value (NPV), and accuracy for CD on day 20 were 100, 70, 86, 100, and 90, respectively. Sensitivity, specificity, PPV, NPV, and accuracy for CD on day 22 were 100, 76, 90, 100, and 92, respectively. Pairwise comparison of receiver operating characteristics curve analysis indicated no differences (P = 0.47) between CD on days 20 and 22 (area under the curve = 0.82 and 0.84, respectively). In conclusion, CD successfully detected most non-pregnant replacement heifers on day 20 and 22, while false negative results were absent (NPV = 100%).
The objective of this study was to evaluate the uterine microbiota composition of cows on day 15 of the estrous cycle. Non-pregnant Bos taurus beef cows (n = 23) were exposed to a pre-synchronization step followed by the 7-d CO-Synch estrus synchronization protocol. On days -10, -3, 0 (exogenously induced ovulation), 7 and 14, transrectal ultrasonography was performed to evaluate ovarian structures, ensure synchrony, and determine the side of ovulation. Cows were harvested on day 15 and individual swabs were collected from each uterine horn using aseptic techniques. DNA was extracted and the entire (V1-V9 hypervariable regions) 16s rRNA gene was sequenced. Sequences were analyzed using the QIIME2 Pipeline. Across all samples, 22 phyla, 130 families, 215 genera, and 90 different species were identified. Butyrivibrio, Bacteroidales RF16 group, Clostridia_UCG-014, and Moraxellaceae, had different (P < 0.05) relative abundances in the ipsilateral compared with contralateral horns, whereas Proteobacteria, Acinetobacter, Bradyrhizobium, Lachnospiraceae FCS020 group, Nanoarchaeota, Woesearchaeales, and Prevotellaceae YAB2003 group tended (P < 0.10) to differ between ipsilateral and contralateral horns. In conclusion, there were significant differences in the composition of the microbial community of the ipsilateral and contralateral horn of cows on day 15 of the estrous cycle.
The objective of this study was to evaluate the effects of estrus expression on uterine microbiota composition of cows on day 15 of the estrous cycle. Non-pregnant Bos taurus beef cows (n = 23) were exposed to a pre-synchronization step followed by the 7-d CO-Synch estrus synchronization protocol. On days -10, -3,0 (exogenously induced ovulation),7 and 14, transrectal ultrasonography was performed to evaluate ovarian structures, ensure synchrony, and determine the side of ovulation. Estrotect patches were applied on day -3, and cows with an activated patch (rubbed > 50%) on day 0 were considered to have displayed heat. Cows were harvested on day 15 and individual swabs were collected from each horn using aseptic techniques. DNA was extracted and the entire (V1-V9 hypervariable regions)16s rRNA gene was sequenced. Sequences were analyzed using the QIIME2 Pipeline. Burkholderiaceae, Chitinophagaceae, Rikenellaceae, Burkholderia, Rikenellaceae RC9 gut group, Lachnospiraceae AC2044 group, Vibrionimonas, Prevotellaceae UCG-001, and Rikenellaceae dgA-11 gut group abundances differed significantly (P < 0.05) in cows that exhibited estrus compared with non-estrual cows. In conclusion, there were significant differences in the composition of the microbial community between cows that exhibited estrus and non-estrual cows.
The objective of this study was to evaluate the use of corpus luteum (CL) color doppler (CD) ultrasonography and pregnancy associated glycoproteins (PAG) for early pregnancy diagnosis and examine their ability to predict late embryonic/early fetal mortality (LEM) in Bos taurus beef replacement heifers. Beef heifers (n = 178) were exposed to a 7-d CO-Synch + CIDR protocol followed by fixed-time artificial insemination (day 0). On days 20 and 22, B-mode and CD ultrasonography were performed to evaluate CL morphometries and blood perfusion, respectively. Heifers were considered non-pregnant when CL area was < 2 cm 2 or estimated luteal blood perfusion was ≤ 30% of the total luteal area. Blood samples were collected on days 25 and 29 to estimate circulating concentrations of PAG. Conventional ultrasonography on day 29 and 94 was utilized to determine pregnancy status and considered the gold standard method for pregnancy diagnosis. Pregnant heifers had greater (P < 0.01) CL diameter, area, volume, and blood perfusion when compared to non-pregnant heifers on days 20 and 22. Accuracy of CD on days 20 and 22, and PAG on day 25 and 29 were 91, 94, 96 and 98%, respectively. No false-negative results were observed for CD on both days 20 and 22 (negative predicted value = 100%) and false-positive results represented 8 and 6% of the diagnoses. Heifers that experienced LEM between days 29 and 94 of gestation had decreased luteal (P = 0.02) volume on day 20 and tended (P = 0.07) to have decreased concentrations of PAG on day 29 compared with heifers that maintained pregnancy. However, both CD and PAG failed to predict embryonic mortality. In conclusion, CD successfully detected most non-pregnant replacement heifers as early as day 20 of gestation, while resulting in no false negative diagnoses. Both CD and PAG failed to predict LEM in the present study.
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