No abstract

The transcriptome of peripheral white blood cells (PWBCs) are indicators of an organism’s physiological state, thus making them a prime biological sample for mRNA-based biomarker discovery. Here, we designed an experiment to evaluate the impact of delayed processing of whole blood samples on gene transcript abundance in PWBCs. We hypothesized that storing blood samples for 24 h at 4 °C would cause RNA degradation resulting in altered transcriptome profiles. There were no statistical differences in RNA quality parameters among samples processed after one, three, six, or eight hours post collection. Additionally, no significant differences were noted in RNA quality parameters or gene transcript abundance between samples collected from the jugular and coccygeal veins. However, samples processed after 24 h of storage had a lower RNA integrity number value (P = 0.03) in comparison to those processed after one hour of storage. Using RNA-sequencing, we identified four and 515 genes with differential transcript abundance in samples processed after storage for eight and 24 h, respectively, relative to samples processed after one hour. Sequencing coverage of transcripts was similar between samples from the 24-h and one-hour groups, thus showing no indication of RNA degradation. This alteration in transcriptome profiles can impair the accuracy of mRNA-based biomarkers, therefore, blood samples collected for mRNA-based biomarker discovery should be refrigerated immediately and processed within six hours post-sampling.

Over the last four decades, several advances in reproductive biotechnologies have helped beef producers improve genetic traits of their cattle, tighten the breeding season and shorten the calving season, leading to an increase in overall profitability of cow-calf production systems. However, even with these advancements, reproductive failure and embryo mortality are still a major cause for economic loss in beef production. Recently, we projected a loss of $6.25 per exposed cow for every 1% decrease in pregnancy rate, with an estimated gross loss of $2.8 billion annually in the United States due to pregnancy failure in beef females. It is estimated that 75 to 80% of embryonic loss occurs by d 20 of gestation; a large portion of these losses occur during the first week of gestation and likely are caused by issues relating to fertilization failure, incompetence of embryos originated from poor quality oocytes and suboptimal uterine conditions. Furthermore, within the first month of gestation, nearly half of all cows submitted to breeding will not be pregnant 30 d later, and another 5% will lose their pregnancy by d 100 of gestation. In addition, breeding related costs, including bull purchase, breeding soundness exam, estrous synchronization, semen purchase, labor associated with artificial insemination and pregnancy diagnosis, are estimate at $65 per cow exposed. Assuming a 90% pregnancy rate at the end of the breeding season, and a scenario where all 30 million beef females in the U.S. are exposed to fixed-time artificial insemination and undergo one pregnancy diagnosis, the added lost revenue of not producing a live calf to sell at weaning and the cost of breeding, would represent a loss of over $21 billion annually in the United States. Strategies that reduce pregnancy loss in beef cattle are essential to improve productivity and profitability of cow-calf production systems.

The objective of the study was to examine how L-citrulline supplementation to ewes during mid-gestation influences placental activity, placental blood flow, lamb body weight and carcass characteristics. Two studies were completed. A pharmacokinetic study to compare circulating plasma amino acid concentrations after a single intravenous injection of 155 µmol/kg BW L-citrulline or after an isonitrogenous amount of L-alanine (control; 465 µmol/Kg BW). Increases (P < 0.05) in circulating citrulline concentrations were detected for 8 h after L-citrulline injection versus the control. Similarly, increases (P < 0.05) in circulating arginine concentrations were detected for 24 h after L-citrulline treatment. The second study used 12 ewes with twin pregnancies. Daily intravenous injections of either L-citrulline or L-alanine were administered for 39 d from d 42-45 to 81-84 of gestation. Ewes were limit-fed at 85 % daily energy requirements during the injection period. A decrease (P < 0.0001) in body weight was observed in both treatment groups during this period. No treatment differences were observed in circulating pregnancy-specific protein B concentrations or placental blood flow during the treatment and post-treatment gestational period. No treatment differences were observed in lamb survival nor in lamb birth, weaning and slaughter weights. Treatment did not influence lamb carcass composition or organ weights. However, there was a tendency (P = 0.10) for an increase in antral follicle numbers in ovaries from ewe lambs derived from ewes treated with L-citrulline. In summary, a daily L-citrulline injection increased both circulating citrulline and arginine concentrations in ewes, but daily L-citrulline injections during mid-gestation did not produce any detectable changes in placental activity and blood flow, neonatal and postnatal lamb development, and lamb carcass composition at slaughter. In conclusion, no benefits in placental function and lamb development were observed after providing L-citrulline during mid-gestation in ewes exposed to a mild energy restriction, but there was an indication that follicle numbers in ewe lambs were positively influenced by L-citrulline treatment during fetal development.

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%).