Immune response, glucose metabolism, and performance of stressed feeder calves fed inorganic or organic chromium.

Abstract

One hundred twenty-five Angus crossbred steers (215 +/- 2 kg initial BW) were blocked by weight and assigned to pens. Pens were randomly assigned to treatment (six pens/treatment). Treatments consisted of 1) control (no supplemental Cr), 2) CrCl3, 3) high-Cr yeast, or 4) Cr nicotinic acid complex. Chromium was added to provide .4 mg of supplemental Cr/kg of DM. Steers were fed diets containing 90% corn silage (DM basis) and 10% soybean meal-mineral-vitamin supplement. Steers were allowed to consume the diets on an ad libitum basis during the 56-d study. Performance was not affected by treatment. On d 52, steers supplemented with high-Cr yeast had a greater response to an intradermal injection of phytohemagglutin (PHA) for 8 h after injection than control steers (P < .10) or those supplemented with CrCl3 (P < .05) or Cr nicotinic acid (P < .05). Peripheral lymphocytes from steers supplemented with Cr nicotinic acid had a greater (P < .05) blastogenic response to 12.5 micrograms PHA/mL than lymphocytes from steers supplemented with CrCl3. After an i.v. infusion of glucose (.25 g of glucose/kg BW), plasma glucose tended (P < .11) to decrease at a faster rate from 15 to 45 min after infusion in steers fed Cr nicotinic acid. Steers supplemented with Cr nicotinic acid had greater (P < .05) serum insulin 15 and 30 min after infusion than those supplemented with CrCl3 and high-Cr yeast. Controls had lower serum insulin than those supplemented with Cr nicotinic acid 30 min after infusion.(ABSTRACT TRUNCATED AT 250 WORDS)