M. L. Eastridge1 and X. Qiu
The Ohio State University Department of Animal Sciences
Abstract
Thirty Holstein, multiparious cows were allocated into 15 blocks based on current milk yield and projected 305-day mature equivalent for milk yield, and cows within a block were assigned to one of two sources of calcium soaps fed at 1.99% of the diet. Cows were fed a common diet for three days and then cows were fed experimental diets for 30 days. The trial was conducted during May and June 2000. The experimental diets consisted of 24.6% alfalfa hay, 17.0% corn silage, and 58.4% concentrates. The DM intake, milk yield, milk fat, milk protein, milk urea nitrogen, and change in body condition score were not different between the two treatments. Calcium soaps can be used to increase energy intake and animal performance, but differences in animal performance to feeding different products may be minimal depending on the chemical nature of the specific products under consideration.
Introduction
A considerable amount of research has been conducted on dietary supplementation with fat (Chilliard, 1993). Fat is added to diets for lactating dairy cows to increase energy intake without compromising rumen function by excessive dietary levels of nonstructural carbohydrates. However, excessive amounts of unsaturated fat in the rumen will decrease fiber digestibility, feed intake, and milk yield. Rumen inerts fats have been developed over the years to increase energy intake without negatively affecting rumen function. The natural, unsaturated fats are usually the first level of added fat because they are less expensive. For even higher levels of fat in the diet, the inert fats are used. Inert fats are primarily based on a protective coating, hydrogenation (making more saturated), or calcium soaps, with the later two methods being common in the US. Several different inert fat products are available, including different products consisting of calcium salts.
The purpose of this short-term trial was to examine the performance of lactating dairy cows when fed different sources of calcium soaps: Megalac® (Church and Dwight Co., Inc., Princeton, NJ) consisting of calcium salts of palm oil fatty acids and Rumolac® (Robt Morgan, Inc., Paris, IL) consisting of calcium salts of soy fatty acids.