Efficiency of nutrient utilization and reproductive performance of pre-pubertal anestrous dairy heifers supplemented with inorganic and organic chromium compounds

An on-farm trial was conducted to ascertain the effects of chromium supplementation on the nutrient utilization and reproductive performance of cross-bred (Bos taurus x Bos indicus) prepubertal anestrous dairy heifers. Chromium was supplemented (0, 0.25, 0.5 and 1.0 mg kg(-1) diet dry matter) as chromium chloride hexahydrate or chromium-yeast complex. The intake of the total digestible nutrients (P < 0.01) and body weight gain (P < 0.05) increased with supplementation of chromium. Chromium-yeast supplementation resulted in a dose-dependent increment (P < 0.01) in the total digestible nutrient intake. Intake and apparent absorption of chromium increased linearly (P < 0.001) with the dose. Chromium chloride tended to be better absorbed (P < 0.10) than the chromium-yeast complex. The source of supplemental chromium did not affect the plasma concentrations of glucose, cholesterol, total protein and albumin. The postprandial plasma glucose concentration in the control group increased by 38% versus 0.27 and 1.1% in the heifers supplemented with 1.0 mg Cr kg(-1) dry matter as chromium chloride and chromium-yeast complex, respectively. The postprandial increment in the plasma cholesterol was also generally lower in the supplemented heifers. The plasma chromium concentration varied (P < 0.05) between the groups, although it was difficult to correlate these changes with the sources and doses of supplemental chromium. Chromium chloride and chromium-yeast supplementation resulted in similar changes in the plasma concentrations of copper, zinc, iron and manganese (P > 0.05). Plasma concentrations of copper and zinc, which increased (P < 0.001) with chromium supplementation, declined quadratically (P < 0.05) as the dose of supplemental chromium increased. At the end of the supplementation, two, four and three heifers fed with 0.25, 0.5 and 1.0 mg Cr kg(-1) dry matter (as chromium chloride), respectively, developed Graffian follicles and showed estrus; the numbers were one, three and four in the corresponding groups fed with chromium-yeast complex and one, two and three heifers amongst them showed estrus. All the supplemented animals showing estrus conceived and no abortion was reported during the first trimester of their pregnancy. It was concluded that chromium supplementation could appreciably enhance the nutrient utilization and the reproductive performance in anestrous dairy heifers and inorganic trivalent chromium (CrCl3.6H(2)O) supplementation might be as useful as a chromium-yeast complex for this purpose. (c) 2006 Society of Chemical Industry.