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 hydrochloride and a supplemental Zn-amino acid complex in growth performance of feedlot cattle. It was hypothesized that improvements to trace mineral status through supplementation would improve cattle health and growth performance. After completion of our first objective, it was determined that inorganic (sulfates) trace mineral supplementation decreased ruminal dry matter digestibility, but hydroxylated trace mineral supplementation had no impact on dry matter digestibility, relative to no trace mineral supplementation. Additionally, Mn and Cu from hydroxy sources were less soluble in the rumen, and Cu from hydroxy sources was equally soluble in the abomasum when compared with the sulfate source. Hydroxy trace mineral sources are less soluble in the rumen, which can prevent negative trace mineral and dietary component interactions within the rumen. After completion of our second objective, we determined that steers with mildly deficient trace mineral status experienced greater body weight loss in response