PSVIII-B-3 - Comparison of Telomere Length in Leukocytes of Control and Prenatally Stressed Brahman Bull and Heifer Calves

Abstract: Telomeres are comprised of G-rich nucleotide sequences (5’-TTAGGG-3’) at the chromosome termini that are responsible for protecting chromosomes; however, attrition of these sequences has been observed due to aging and stress. The purpose of this study was to compare telomere length (TL) in control and prenatally stressed (PNS) calves. Mature Brahman cows inseminated to a single Brahman sire in 2018 were assigned to be either Control (n=35; not transported) or PNS (n=37; 2 h of transportation at 60, 80, 100, 120, and 140±5 d of gestation). Jugular blood samples were obtained by venipuncture from 10 Control (5 bulls and 5 heifers) and 10 PNS (5 bulls and 5 heifers) calves at 25±2 d of age. Peripheral leukocytes were isolated and genomic DNA was extracted utilizing silicone membrane spin column kits. The relative quantity of telomere products, which is proportional to the average TL, was determined by multiplex quantitative PCR analysis using the ratio of bovine telomere and β-globulin DNA (T/S ratio). An absolute standard of bovine telomere (10¹²–10⁷ dilution series) and β-globulin (10⁹-10⁴ dilution series) genes was utilized to produce relative copy number. All samples were processed in triplicate and samples were included if the triplicate Cq difference was less than 0.25 cycles. Data were analyzed using ANOVA. TL differed by sex (P< 0.03; bulls 11,959±211; heifers 12,850±366) and treatment (P< 0.02; Control 12,895±278; PNS 11,913±303). There was not an interaction of sex and treatment (P >0.43) although TL of Control heifers (13,482±396) exceeded the TL of PNS bulls (11,609±348). These observations of fewer copies of telomere sequences suggest an influence of sex on TL within 1 month of age; and, that prenatal transportation stress may increase attrition of telomeres in cattle. Support: USDA NIFA Award No. 2019-67015-29573