Year of Publication

2007

Document Type

Dissertation

College

Agriculture

Department

Animal Science

First Advisor

Merlin D. Lindemann

Abstract

The objectives were to investigate the effects of chromium (III) picolinate (CrPic; up to 2,000 ppb of Cr) on growing pigs subjected to a variety of stressors including thermal, immune, or dietary stress and to examine the effects of CrPic on steroidogenesis from adrenocortical cells. In the thermal stress study, high ambient temperature caused reduced weight gain and feed consumption (P andlt; 0.01), and low ambient temperature caused increased feed intake and feed:gain (P andlt; 0.01). However, these effects were not moderated by CrPic, and respiratory rate, plasma cortisol, or plasma glucose were unaffected by CrPic. In the immune stress study, pigs challenged with lipopolysaccharide (LPS) lost 951 g during 12 hours post injection, while the phosphate buffer saline (PBS) injected group gained 170 g (P andlt; 0.001). The LPS group showed higher rectal temperature (P andlt; 0.05), higher respiratory rate (P andlt; 0.05), greater plasma cortisol (P andlt; 0.001), and lower plasma glucose (P andlt; 0.05) than the PBS group. These effects were not ameliorated by CrPic. In the dietary stress study, pigs fed the high-fat diet (HFD) gained weight faster (P andlt; 0.05), consumed less feed (P andlt; 0.001), and had lower feed:gain (P andlt; 0.001). Plasma insulin concentration on d 14 decreased with CrPic (P andlt; 0.05) in a linear manner (P = 0.05). Consumption of the HFD resulted in increases of slaughter weight, perirenal fat, and back fat measurements (P andlt; 0.01). The CrPic resulted in linear reductions of carcass weight, last rib fat, last lumbar fat and average backfat (P andlt; 0.10). The effects of CrPic on carcass fat measurements were more significant in barrows than gilts. In the adrenocortical cell study, forskolin stimulated cortisol and DHEAs secretion from H295R cells. CrPic inhibited aspects of steroidogenesis in agonist-stimulated adrenocortical cells. Overall, dietary CrPic was unable to moderate the stress related effects due to high ambient temperature, low ambient temperature, or an endotoxin challenge. However, CrPic attenuated effects of HFD, mainly on body fat accretion of pigs, especially in barrows, and CrPic inhibited steroidogenesis in stimulated adrenocorticoid cells.

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