Trace mineral supplementation in feedlot cattle: implications for the inflammatory response, growth, and carcass characteristics

Abstract

Trace minerals are important components of many biological functions, including growth and development, and the immune response. Trace minerals are often supplemented to cattle, but interactions within the rumen and poor bioavailability can lead to decreased trace mineral status. Additionally, stressors such as transit and disease challenges, and perhaps growth-promoting technologies, may alter trace mineral needs, although this relationship has not been investigated. This research was designed to: 1) examine the effect of trace mineral source and concentration on ruminal dry matter digestibility and mineral solubility, 2) determine the effect of trace mineral status on the response to a trace mineral injection in feedlot steers, 3) determine the effect of a trace mineral injection prior to transit, on beef cattle response to transit and growth and carcass characteristics, and 4) investigate the interaction between the βagonist ractopamine CHAPTER 2. REVIEW OF THE LITERATURE Brief Review of the Biological Functions of Copper, Manganese, Selenium, and Zinc Copper Copper is required for the function of several enzymes within the body, including the antioxidant enzyme Cu/Zn superoxide dismutase (SOD), which catalyzes the conversion of the superoxide radical to hydrogen peroxide within the cytosol (Tainer et al., 1983). Copper is also a component of the enzyme ceruloplasmin, which acts as a Cu transport protein (Hsieh and Frieden, 1975) and a ferroxidase that oxidizes ferrous Fe to ferric Fe (Patel et al., 2002). Copper is also essential as a part of lysyl oxidase, an enzyme that is required for formation of covalent cross-links between elastin and collagen within the extracellular matrix (Kagan and Li, 2003), as well as part of cytochome C oxidase, also known as Complex IV within the electron transport chain, necessary for ATP production (Tsukihara et al., 1995). Manganese Manganese is required for the function of Mn-SOD, which is an isoform of SOD found in the mitochondria (Weisiger and Fridovich, 1973). Manganese plays a significant role in carbohydrate metabolism as a part of pyruvate carboxylase, and phosphoenolphyruvate carboxykinase, and also nitrogen metabolism, as a cofactor for arginase, critical in the urea cycle (Leach and Harris, 1997). Manganese is also required for the function of glycosyltransferases, which synthesize mucopolysaccharides in cartilage, to allow for proper bone formation (Suttle, suggesting incorporation of injectable TM into a biological process. The increase in liver Se in response to MM was greater in CON vs. DEF (P = 0.02), suggesting TM from injection were utilized rather than stored in DEF steers. Liver Se and Cu (P < 0.05) were elevated through at least d 30 by MM. Dietary TM deficiency decreased neutrophil bacteria killing ability and increased myeloperoxidase (MPO) degranulation (P < 0.04) as measured on d 0, 1, 13, and 14 during the repletion period, while injection had no impact. Within CON animals, total MPO was greater in animals that received TM injection, but injection di...