Effect of Acute Inflammatory Events and Parity on Length of Telomeres in Brahman Cattle

Abstract

Two experiments were conducted to evaluate the effects of acute inflammation (Experiment 1) and parity (Experiment 2) on peripheral blood leukocyte telomere length (TL) in Brahman cattle. Experiment 1 utilized 11 heifers (20-21 mo of age) grouped into either control (n =6) or lipopolysaccharide (LPS) treatment (n = 6) groups. Heifers were fitted with vaginal temperature probes 7 d prior to treatment. Heifers were weighed, BCS recorded, and bled by jugular venipuncture prior to each treatment. The LPS doses increased on corresponding treatment days (d 0, 0.25 µg/kg; d 7, 0.50 µg/kg; d 14, 0.75 µg/kg). Sickness behavior was observed post treatment. In both experiments, quantitative PCR methods were utilized to determine quantity of telomere sequences and bovine β-2-globulin gene. Absolute standard curves were created using serial dilutions of double-stranded DNA oligonucleotides of bovine telomere and β-2-globulin genes. Statistical analyses were conducted utilizing mixed linear models with the MIX procedure of SAS. The LPS treatment did elicit a febrile response observed as increased maximum vaginal temperature (VT) (P = 0.0429), increased change in VT (P < 0.0001), and decreased time to maximum VT (P < 0.0001). No relationship was seen between TL for treatment (P = 0.3554), day (P = 0.7338), or the interaction of treatment and day (P = 0.9441). A trend was observed for increased days of age and decreased TL (P = 0.0715). Experiment 2 involved 19 cows [primiparous (n = 8) and multiparous (n = 11)] sampled on d -28, d + 7, and d + 28 pre- and post-calving. Cows were weighed and BCS recorded on sample days as well as observed for duration of labor and calving ease. A reduction in TL (9224.5 copies of telomere) was observed between parity 1 and 2 (P = 0.0223), but no differences were seen in sample day (P = 0.2315) or the interaction of parity and day (P = 0.7696). A greater degree of endotoxin exposure than utilized in this study may be needed to adequately assess TL response to acute inflammation. Parity was negatively associated with peripheral blood leukocyte TL in Brahman cows.