Utilization Work Group Relationships Between Cattle Genetic Polymorphisms and Profitability Traits in Tall Fescue Forage Systems

Introduction Ergot alkaloid toxins produced by Neotyphodium coenophialum in association with tall fescue (Festuca arundinacea) have been shown to affect numerous physiological systems of livestock resulting in decreased profitability of those enterprises. One management technique that has been promoted to reduce the production losses in cattle is crossbreeding (Brown et al., 1997). In addition to crossbreeding Bos indicus (Brahman) and Bos taurus (Angus, Hereford, Senepol, etc.) cattle, one also can rotate cattle off of toxic fescue prior to the breeding season (Brown et al., 2000). While it was apparent that heterosis improved cattle productivity, specific genetic effects related to an animal’s tolerance to ergot alkaloids is not known. Heat shock proteins (HSPs), also known as stress proteins, are present in all cells of the body. The HSPs increase when an animal is subjected to stressors such as heat, cold, oxygen deprivation, and other conditions (for review see Lindquist and Craig, 1988). Although HSPs are present in high concentrations during cellular stress, they also are present at normal temperatures and play vital roles in normal cell function via protein chaperones, immune cell regulation, and steroid receptor function (Bresnick et al., 1989; Morishima et al., 2000; Smith et al., 1995). Prolactin is a protein hormone secreted by the lactotropic cells of the anterior pituitary. The primary role of prolactin in mammals is the development of the mammary gland and lactation in the mature mammary gland during the last stage of pregnancy and following parturition (McCann, 1988; Bawden and Nicholas, 1999). Consumption of endophyte-infected tall fescue results in reduced feed intake, weight gains, blood flow to the periphery, pregnancy rates, as well as lower concentrations of serum prolactin and milk production (Nihsen et al., 2004; Browning, 2000; Samford-Grigsby et al., 1997). In this report, the results of studies are presented that evaluated the relationships between cattle productivity and genomic polymorphisms in cattle. Specifically, the enhancer region of the prolactin gene and coding sequences of the HSP-70 gene in Bos indicus and Bos taurus cattle were genotyped and related to cattle productivity while grazing toxic tall fescue.