Stress Effects on Chromium Nutrition of Humans and Farm Animals

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<strong>Stress</strong> effects on chmmium nutrition of humans and farm animals likely that training which leads to obvious adaptive increases in strength, endurance, heart stroke volume etc. leads to increased conservation of body Cr stores. Adaptive changes may involve a redistribution of Cr in specific tissues which is supported by animal studies. Vallerand et al. (1984) reported that exercise-trained rats displayed significantly higher Cr concentrations in the heart and kidneys compared with respective tissues of controIs. Humans who train regularly may also compensate for increased Cr losses associated with acute exercise with increased caloric intake, resulting in higher Cr intake. Improved dietary habits including decreased consumption of simple sugars (which leads to enhanced Cr Iosses) would aIso lead to improved dietary Cr status. However, peopIe who exercise strenuously but sporadically to Iose weight would not have increased dietary intake, would not have the adaptive mechanisms of training, and would not have improved Cr nutrition, but would have low intake coupled with high Cr losses due to acute exercise. This couId obviously lead to decreased Cr stores. A direct correIation of Cr losses with stress was shown by Anderson et al. (1991; Figure 1) who reported a correlation of serum cortisol and urinary Cr Iosses associated with strenuous head out immersion exercise. Serum cortisol is reIated to the degree of exercise intensity and is therefore a measure of exercise stress (Kuoppasalmi et al., 1980). Increased exercise capacity associated with carbohydrate loading was less stressful based on serum cortisol and also less stressful based on decreased Cr Iosses (Anderson et al., 1991). 0 400 800 1200 1600 Post-exercise serum cortisol (nmol/l) Figure 1. Correlation of urinary chromium losses and post-exercise serum cortisol. Blood samples for serum cortisol were taken immediately following head out immersion exercise at 25°C. Urine samples were collected during the four hours of exercise and two hours following. (0) Control diet period; (I) following carbohydrate Ioading.(Source: Anderson et al., 1991) 270
R.A. Anderson Severe forms of stress such as those associated with physical trauma severe enough to be taken to a shock trauma unit resulted in severaLfold increases in Cr losses (Table 2; Bore1 et al., 1984). Chromium losses decreased as the patients improved and the degree of stress decreased. <strong>Stress</strong> effects in farm animals The effects of stress on Cr metabolism observed in humans are also observed in farm animals. Chang and Mowat (1992) reported that Cr in the form of high Cr yeast increased average daily gain by 30% and feed efficiency by 27% in steer calves folIowing the stress of shipping. During the growing period, Cr had no effect on weight gain or feed efficiency. Chromium also decreased serum cortisol and increased immunogIobulin M and total immunoglobins in caIves fed diets with soybean meal but had no effect in calves fed urea-corn supplementation. Humoral immune responses of periparturient and early lactating dairy cows were also improved by supplementa Cr (Burton et al., 1993). These data suggest that stressed animals fed normal diets may be showing signs of Cr deficiency including decreased feed efficiency, increased stress hormone, morbidity, and impaired immune function. These signs of Cr deficiency are only observed in the stressed animals. The stress associated with shipping appears to increase the Cr require- ment of the steers. Long-acting oxytetracydine which is given to combat stress has effects similar to Cr but when Cr and tetracycline were administered GnuItaneousIy there were no additive effects. The authors postulated that by reducing stress, long-acting injectable oxytetracycline alleviated Cr Iosses and prevented signs of marginal Cr deficiency. Klasing and Roura (1991) demonstrated that administration of antibiotic to chicks decreased immunoIogic stress by reducing interleukin-1 Ievels resuhing in unproved growth. Chromium supplementation to unstressed growing-finishing steers had no effect on carcass composition and tissue mineral concentrations or any performance characteristics. The benefica1 effects of Cr in stressed animals demonstrates that stress increases Cr requirements. Chromium-has also been shown to have beneficial effects on body composition, glucose, Iipids and related parameters in swine. Steele et aI. (1982) reported that high levels of insulin-potentiating or biologicahy active Cr increased growth and feed efficiency in pigs. Page et al. (1993) reported increased daiIy gain, Iongissimus muscle area, increased percentage of muscling and decreased tenth rib fat in pigs following Cr supplementation in the form of Cr picolinate but not with chromium chIoride. Evock-CIover et al. (1993) reported improved HDL-cholesterol, total cholesterol: HDL ratio, glucose, insulin and insuhnglucose ratio in both control and growth hormone treated pigs following supplementation with Cr in the form of Cr picolinate. Supplementa Cr counteracted the negative effects of growth hormone on glucose and insulin variables. Chromium effects were greater at 60 kg than at 4.5 kg. Chromium also increased serum growth hormone in the growth hormone- treated pigs. 271
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Stress Effects on Chromium Nutrition of Humans and Farm Animals

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