PERFORMANCE AND METABOLIC RESPONSES OF YOUNG DAIRY CALVES FED DIETS SUPPLEMENTED WITH CHROMIUM TRIPICOLINATE

Forty-two Holstein calves were used to study performance and metabolic responses when milk replacer and then postweaning starter were supple mented with 1 ppm of Cr as Cr-tripicolinate, From birth through 8 wk o f age, supplemental Cr tended to improve the growth performance of bul l calves but not of heifer calves. Starter intake and feed efficiency were not affected by supplemental Cr. From 1 to 5 wk of age, plasma co rtisol concentrations sampled just prior to feeding decreased, and con centrations of insulinlike growth factor-I increased. All calves appea red to become less sensitive to insulin as they aged. From 1 to 5 wk o f age, plasma glucose and insulin concentrations gradually diverged fo r all calves; glucose concentrations decreased, and insulin concentrat ions increased. In addition, glucose clearance rate, measured by i.v. glucose tolerance tests, was more rapid when calves were 2 wk of age t han when calves were 8 wk of age. The glucose clearance rate was great er in heifer calves than in bull calves but was not affected by supple mental Or. Entry of plasma glucose following an i.v. propionate load w as also greater in heifer calves than in bull calves but was not affec ted by supplemental Cr. Plasma nonesterified fatty acids were lower in calves fed milk replacer or starter supplemented with Cr than in cont rol calves, although this effect diminished as calves aged. This findi ng was considered to be indirect evidence of enhanced insulin sensitiv ity in calves fed milk replacer or starter supplemented with Cr. Overa ll, data suggested that supplemental Cr-tripicolinate had minor effect s on the metabolism and growth performance of conventionally managed d airy calves. The most notable effects occurred during the initial few weeks of life.