Circulating microRNA as candidates for early embryonic viability in cattle.

Blood-borne extracellular vesicles (i.e., exosomes and microvesicles) carrying microRNAs (miRNAs) could make excellent biomarkers of disease and different physiologic states, including pregnancy status. We tested the hypothesis that circulating extracellular vesicle-derived miRNAs might differentiate the pregnancy status of cows that had maintained pregnancy to Day 30 from non-pregnant cows or from those that exhibited embryonic mortality between Days 17 and 30 of gestation. Cows were randomly assigned for artificial insemination with fertile semen (n = 36) or dead semen (n = 8; control group) on Day 0 (day of estrus). Blood was collected from all animals on Day 0 and on Days 17 and 24 after artificial insemination. Cows receiving live sperm were retrospectively classified as pregnant on Day 30 (n = 17) or exhibiting embryonic mortality between Days 17 and 30 (n = 19). Extracellular vesicles from Day 17 and 24 samples were isolated from serum using ultra-centrifugation, and their presence was confirmed by nanoparticle tracking and Western blot analyses (for CD81) prior to RNA extraction. MicroRNA sequencing was performed on pregnant, embryonic-mortality, and control cows (n = 4 per day), for a total of 24 independent reactions. In total, 214 miRNAs were identified in serum, 40 of which were novel. Based on differential abundance parameters, we identified 32 differentially abundant loci, representing 27 differentially abundant mature miRNA. At Days 17 and 24, specific miRNAs (e.g., miR-25, -16b, and -3596) were identified that differentiated the pregnancy status. In summary, we identified several circulating extracellular vesicles derived miRNAs that differ in abundance between embryonic mortality and pregnant cows.

Impacts of Rumen Degradable or Undegradable Protein Supplementation on Supplement Intake and Performance of Yearling Heifers and Cows Grazing Dryland Pastures.

Angus and Red Angus-based yearling heifers (n = 40) and lactating cows (n = 51) were each used in a complete randomized design and stratified by weight and body condition score to one of two treatments: (1) pressed supplement block containing rumen undegradable protein (RUP) and (2) pressed supplement block containing rumen degradable protein (RDP). Heifer and cow supplement intake displayed (p < 0.01) a treatment × period interaction. The RUP heifers and RDP cows consumed more in Period 2 than Period 1, whereas RDP heifers and RUP cows consumed more in Period 1 than Period 2, respectively. Intake rate demonstrated (p < 0.01) a treatment effect for heifers, with RUP consuming supplement faster than the RDP treatment. Intake rate for cows demonstrated (p < 0.01) a treatment × period interaction with RUP cows in Period 1 having faster intakes than Period 2, and RDP cows having the inverse. Cow intake variation displayed (p < 0.01) a treatment × period interaction with RUP cows having more variation in Period 2, while RDP cows had less variation in intake in Period 2. In conclusion, RDP and RUP impacted intake behavior of cows and heifers but had minimal impacts on performance.