The Utilization of Dicyandiamide and Urea by Lactating Dairy Cows1

Abstract

Twenty-four cows were used in a lactation study to evaluate soybean oil meal, urea and dicyandiamide as nitrogen sources in low-protein concentrate mixtures. Each nitrogen source supplied approximately one-third of the nitrogen in the concentrate mixture. All cows were limited to a protein inake of 90 to 100% of Morrison's minimum protein standards. A medium-quality timothy hay was fed as the sole roughage. No significant differences in milk production were observed on a lactation basis or during a comparison period of 196-days in length beginning on the 30th day of lactation. The average daily milk yields during this period were 24.4, 22.3 and 22.2 lb. per cow daily for the soybean oil meal, urea and dicyandiamide rations, respectively. Significant differences were observed between rations in respect to body weight losses and blood and milk urea nitrogen levels. During the 196-day period the cows fed the ration containing soybean oil meal averaged 3 lb. gain in weight, whereas the cows in the urea group lost 28 lb. and those fed the dicyandiamide ration lost 86 lb. The difference between the soybean oil meal and dicyandiamide rations was highly significant. Cows fed the soybean oil meal and urea rations had significantly higher blood and milk urea nitrogen values than cows fed the dicyandiamide ration. No significant differences in coefficients of apparent digestibility were observed between the rations, but coefficients of all nutrients with the exception of ether extract were lower for the dicyandiamide ration than the other two rations. Data obtained in this study show that the non-protein nitrogen compound, dicyandiamide, was not used efficiently by dairy cows. Studies are in progress to study this problem further. Copyright © . .