Crude glycerin as a replacement for corn in starter feed: performance and metabolism of pre-weaned dairy calves

Abstract

The purpose of this study was to evaluate the effect of partial replacement of corn in the starter feed with crude glycerin on performance and energy metabolism of liquid-fed dairy calves. Twenty-four newborn individually housed Holstein calves were blocked according to weight and date of birth and randomly assigned to different starter feed treatments during 8 weeks: no crude glycerin; 5% crude glycerin; 10% crude glycerin on dry matter basis. All calves were individually fed daily 4 L of a commercial milk replacer (22.3% crude protein and 19.3% fat). Calves had individual access to starter diet and ad libitum access to water daily. Individual feed intake and faecal scores were recorded daily. Bodyweight and corporal measurements (heart girth, hip width, and withers height) were weekly recorded. From the second week of age, blood samples were collected weekly, 2 h after morning feeding, for determination of plasma glucose and β-hydroxybutyrate concentrations. Ruminal fluid was collected at 4, 6 and 8 weeks of age for determination of pH and short-chain fatty acids. At the end of the eighth week, animals were harvested to evaluate development of the proximal digestive tract. Feed intake, average daily gain, bodyweight or body measurements were not affected (P > 0.05) by the inclusion of crude glycerin in the starter feed. Faecal scores indicated that most of the calves had mild diarrhoea, with no treatment effect. Total short-chain fatty acids and the concentration of individual acids, as well as blood parameters, were not affected (P > 0.05) by the feed treatments. The total forestomach weight, the average weight of each compartment, the maximum capacity of reticulum-rumen, and papillae number, height and width were not affected (P > 0.05). In conclusion, crude glycerin can be used as an alternative energy source, replacing corn up to 10% in the starter feed for liquid-fed dairy calves without affecting growth, rumen development or metabolism.