Changes in energy metabolism and the performance of dairy calves receiving conventional suckler initial concentrate containing glycerol substitution in the corn

Abstract

The objective of this project is to evaluate the effect of replacing corn by crude glycerin in the feed starter on performance and changes in energy metabolism of calves at weaning. Twenty-four newborn dairy calves will be used in a completely randomized design. Starter feed with increasing doses of glycerin replacing corn as an energy source (0, 5 and 10% DM) will be evaluated. The animals of the experiment will be managed according to traditionally recommended in the literature and will be housed in individual hutches, with free access to water, receiving 4L/d of liquid diet (milk replacer) and starter feed ad libitum. Blood and ruminal fluid (tube) will be collected from the second week of life for glucose, lactate, plasma beta-hydroxybutyrate, and N-ammonia and short chain fatty acids in rumen fluid, respectively. Also, at the 2nd., 4th. and 8th. week of life a liver biopsy will be performed for the determination of the activity of the enzymes pyruvate carboxylase and phosphoenolpyruvate carboxykinase. At the the eighth week of life the animals will be slaughtered to evaluate the development of forestomach, with evaluations of weight and volume of compartments, as well as size and number of papillae on the rumen epithelium. (AU)