Chelated chromium for stressed feeder calves

Abstract

Using crossbred calves obtained at feeder sales in Ontario, we evaluated two different sources of organically complexed chromium (Cr) for supplementing corn silage. A preliminary trial was conducted with 12 unstressed steers with or without 1 mg kg −1 chelated Cr during a 56-d growing period. Chelated Cr markedly decreased (P < 0.05) serum cortisol and glucose levels. In the main trial, 72 calves, weighing 233 kg, were randomly allotted to four treatments: control, high-Cr yeast, chelated Cr, and chelated Cr plus chelated Zn, Cu and Mn for the initial 7 d. Morbidity was determined by visual detection followed by rectal temperature checks. One third of morbidity occurred by day 12; two thirds, by day 16. High-Cr yeast tended to reduce morbidity; however, chelated Cr was more effective, resulting in 16.5% morbidity, or less (P < 0.05) than one third of the control. Daily gain was 41% higher (P < 0.05) with chelated Cr during the first 21 d after arrival, mainly due to the marked reduction in number of sick calves. During days 21–35, compensatory gain occurred with the morbid or antibiotic-treated calves. These data indicate that early (relative to peak morbidity) supplementation of stressed feeder calves with chelated Cr markedly reduces morbidity. Key words: Chromium, stress, calves, morbidity, cortisol, steers