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Effects of incremental dietary chromium (Cr3+) on growth, hormone concentrations and glucose clearance in growing goats (Capra hircus)
Published online by Cambridge University Press: 02 June 2006
Abstract
Castrated male black Bengal kids were supplemented daily with 0, 0·5, 1·0, 1·5 and 2·0 mg chromium (Cr3+ as chromic chloride hexahydrate) for 150 days. Metabolic stresses such as a feeding challenge, an intravenous glucose tolerance test (IVGTT) and a short-term (72 h) feed deprivation were imposed on the animals to ascertain if supplemental Cr could alleviate these stresses and whether the stress-alleviating effect could provide an explanatory basis for the performance traits of the supplemented animals. The kids were fed with a concentrate diet containing 0·197 mg Cr/kg DM. DM intake (g/kgw0·75) was lower (P=0·006) in the 0·5 and 1·5 mg groups. Feed efficiency tended (P=0·086) to improve in the Cr-supplemented kids, although a distinct dose response was absent. Basal serum T3 increased linearly (P=0·01) with increased dose of Cr although the post-prandial change did not follow any definite trend. Basal serum insulin increased (P=0·001) linearly while the post-prandial increment was higher (P=0·037) in the control group. The IVGTT indicated that the kids supplemented with 1·5 mg Cr had significantly (P<0·05) higher serum clearance rate and lower half-life for insulin. Serum Cr during the IVGTT declined (P<0·05) until 45 m after glucose infusion and then increased again (P<0·10) at 60 m in the 0·5 and 1·5 mg groups although in the rest of the experimental groups serum Cr was stable during the entire course of the IVGTT. The body weights at the beginning of the fast were higher (P=0·036) in the kids supplemented with 0·5 and 1·5 mg Cr. However, the change in body weight at the end of the 72 h fast did not vary (P>0·10) between the groups. Cr supplementation reduced (P<0·05) serum cortisol level in the supplemented animals consistently throughout the duration of the feed deprivation. Moreover, as the fast progressed serum cortisol tended to increase (P=0·059) in all the experimental groups irrespective of the level of Cr supplementation. It was concluded that inorganic Cr supplementation might appreciably increase serum T3 concentration and reduce the level of cortisol which might augment animal productivity. However, further research with a more sensitive design is required to establish the exact level of Cr supplementation for enhancing performance of livestock.
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- © 2006 Cambridge University Press
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