Date of Award
Doctor of Philosophy (PhD)
Animal Science (Animal, Dairy, and Poultry Sciences)
L. Dwain Bunting
In Exp. 1, 42 calves were fed milk replacer and then starter either with or without 1 ppm supplemental chromium (Cr) as Cr-picolinate. Neither Cr nor sex affected growth performance. With the exception of plasma nonesterified fatty acid concentrations (NEFA), weekly plasma metabolites were not affected by Cr or sex. Pre- and postfeeding plasma NEFA concentrations were lower in Cr-fed calves, but were not affected by sex. AU calves seemed to become less insulin sensitive with age, as plasma glucose became lower and insulin higher as calves became older. During i.v. glucose tolerance tests (IVGTT), calves cleared glucose faster at 2 compared with 8 weeks of age but Cr did not affect clearance at either week. At 2 weeks of age, heifers cleared glucose faster than did bulls. Plasma glucose increases after an i.v. propionate load were greater in heifers than in bulls but were not affected by Cr. In Exp. 2, 34 calves were fed milk replacers either without (BF) or with (HF) added fat and either with or without 1 ppm of dietary Cr as Cr-nicotinate. Neither Cr nor fat affected performance; except, weight gain was greater in HF-fed calves during the period calves received milk alone. Weekly plasma glucose, insulin, and triacylglycerol concentrations were not affected by Cr; however, plasma insulin concentrations tended to be lower in Cr-fed compared with control-fed calves. Weekly NEFA declined in a similar manner for Cr-fed and control-fed calves; however, overall, NEFA concentrations were greater in Cr-fed calves. Weekly cholesterol concentrations were greater in Cr, HF-fed calves and lower in Cr, BF-fed calves compared with controls. Added dietary Cr or fat had minimal effects on plasma metabolites and hormones measured after milk replacer feeding. Using data generated by the IVGTT, a computer modeling procedure predicted that insulin sensitivity was increased in Cr-fed calves but reduced in HF-fed calves compared with controls. Overall, data suggested that Cr had little effect on metabolism or growth performance, but may have improved insulin sensitivity, with the most notable effects occurring in the initial weeks of life.
Depew, Christopher L., "Supplemental Organic Chromium for Dairy Calves." (1998). LSU Historical Dissertations and Theses. 6666.