Digestibility and nitrogen balance of the feed of dairy cows with urea as the sole or partial source of nitrogen

Authors

• M. Kreula Biochemical Research Institute, Kalevankatu 56 b, 00180 Helsinki 18, Finland
• T. Ettala Biochemical Research Institute, Kalevankatu 56 b, 00180 Helsinki 18, Finland

DOI: https://doi.org/10.23986/afsci.71935

Abstract

The digestibility and nitrogen balance tests were performed both with cows on purified protein-free feed (0-feed) with urea as the sole source of nitrogen, and with cows on a urea-rich, low-protein diet (ULP-feed). In addition to ordinary low-protein fodders, ULP-feed contained also as the source of energy so-called hemicellulose and 0-fibre, which are waste products of the cellulose industry. The determinations were made either with chromic oxide as an indicator, or by collecting the faeces and urine separately. The average digestibility percentage of the nitrogen (= urea-N) with 0-cows was 67.0±5.2, that of the dry matter 73.9±5.1 and that of the organic matter 76.6±5.1. With ULP-cows the average digestibility percentage of the total nitrogen was 71.2±4.9 and that of the urea nitrogen varied between 70 and 86. The average digestibility percentage of hemicellulose was 83 and that of the 0-fibre of the sulphite cellulose industry (0-fibre 2) 80. The nitrogen balance was positive in all experiments, + 20.4 ± 20.6 g with 0-cows and + 39,4 ± 16.4 g with ULP-cows per day.