Bovine cytochrome P450 3A28 is responsible for metabolizing ergot alkaloids that cattle ingest when feeding on endophyte-infested tall fescue grass. The objective of this research was to determine associations among genotype, transportation, and stress responses. Angus crossbred steers (n = 47) were genotyped (CC, CG, or GG) for a single-nucleotide polymorphism (C994G) in cytochrome P450 3A28. Genotypes were determined by polymerase chain reaction (PCR) amplification followed by restriction enzyme (Alu1) digestion. Steers were backgrounded on a mixedcultivar tall fescue pasture. Following the stocker phase, steers were transported to the feedlot for finishing. Stress responses were determined 27 h prior to, and 6 and 20 h after transport. Plasma concentrations of prolactin and cortisol, and white blood cell expression of prolactin, cytochrome P450, tumor necrosis factor-alpha, and short form prolactin receptor were our indicators of stress. Both time and genotypic effects were determined. Time (P < 0.05) relative to transportation was associated with expression of all four genes tested. In addition, plasma concentrations of cortisol and prolactin, as well as their ratio were affected (P < 0.05) by time. In contrast, neither genotype nor the interaction between genotype and time affected (P > 0.1) our stress indicators. In previous studies, C994G genotype has been associated with cattle productivity; however, those effects were not observed in this study.
Wary, Megan; Sales, Marites; Williamson, Ben; Coffey, Ken; Looper, Michael; and Rosenkrans, Charles Jr.
"Steer stress response as affected by genotype and transportation,"
Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences. University of Arkansas System Division of Agriculture. 15:100-104.
Available at: http://scholarworks.uark.edu/discoverymag/vol15/iss1/16