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Casein and its Degradation Products in the Utilization of Urea Nitrogen by Lambs¹

West Virginia University, Morgantown

Abstract

Two metabolism trials were conducted with wether lambs to determine the influence of additions of intact casein, acid hydrolyzed casein and enzymatically hydrolyzed casein upon nutrient digestibility and nitrogen utilization. The semi-purified isonitrogenous rations were composed of a purified concentrate mixture, blackstrap molasses and corn cobs and contained either 1.59% or 1.7% nitrogen. Eighty-seven percent of the ration nitrogen was supplied by urea and/or the casein material. Each trial consisted of a 10-day preliminary period followed by a 10-day collection period.

In the first trial 10% of the supplemental nitrogen was supplied by the caseins in the various combinations permitted by 1:1:8 proportions. The combination in which enzymatically hydrolyzed casein supplied 8% of the supplementary nitrogen appeared to improve nitrogen utilization but the response was not significant.

In the second trial 4, 8 and 16% of urea nitrogen were replaced with isonitrogenous amounts of enzymatically hydrolyzed casein. None of the treatments resulted in significant improvement in digestibility of nutrients or in the utilization of nitrogen.

An evaluation of the combined data from trials 1 and 2 revealed a significant improvement in nitrogen utilization and dry matter digestibility when 8% of the supplementary nitrogen was supplied by enzymatically hydrolyzed casein.

¹ Published with the approval of the Director of the West Virginia Agricultural Experiment Station as Scientific Paper No. 642 from the Department of Agricultural Biochemistry and Nutrition and the Department of Animal and Veterinary Science.