Immune response and growth of stressed weanling pigs fed diets supplemented with organic or inorganic forms of chromium.

A 2 x 4 factorial arrangement of treatments was used in a randomized complete block designed study to determine the effects of chromium level and source on growth and immune response of stressed and non-stressed 3-wk-old crossbred weanling pigs (BW was 6.35 kg). Factors included 1) immune stress or control and 2) no supplemental Cr or .2 ppm of supplemental Cr from either CrCl3, Cr-picolinate, or Cr-nicotinic acid complex. The basal diet was a corn-soybean meal-whey diet containing 1.2% lysine. Escherichia coli lipopolysaccharide (LPS) was the stress-inducing agent and was injected on d 7, 10, and 13 of the experiment. Immune challenge with LPS resulted in reduced gain (P < .05) and feed intake (P < .10). Supplementation with Cr was not effective in alleviating the depression in growth due to LPS. However, supplementation of control pigs with Cr tended to improve (P < .10) gain and feed intake. In vitro cellular immune response as measured by a lymphocyte blastogenesis assay was increased (P < .10) in pigs fed supplemental Cr from CrCl3, or Cr-picolinate. Antibody response to sheep red blood cells tended to be increased (P < .10) in pigs supplemented with Cr-nicotinic acid, but antibody response to ovalbumin was decreased (P < .05) in pigs supplemented with organic forms of Cr. At the end of the study, effects of Cr supplementation on lymphocyte proliferative response were investigated before and after ACTH administration. Injections of ACTH resulted in increased (P < .001) serum cortisol levels and increased lymphocyte proliferation. Supplementation of Cr did not affect lymphocyte blastogenic response before or after ACTH injection (P > .10). These data suggest that Cr supplementation was not beneficial during immune stress in pigs.