8.5 Source of Protein Supplementation for Various Forages

Abstract

To make the best use of forages, it is necessary to consider the need for, and source of, nitrogen supplementation of the diet. This paper describes a study of the use of spring barley straw and other forages in the diet of the dairy heifer between 9-18 months of age, 200-300 kg live weight and required to grow at 0.5-0.7 kg per day. In the feeding trials, fixed amounts of the diets were fed.In the first series of experiments, it was demonstrated that spring barley straw could supply up to 70% of the dry matter (DM) intake in mixed straw:concentrate diets when an adequate protein content was supplied. Thus, when fish meal was added, the required growth rates were obtained, as demonstrated in Figure 8.5.1 (Smith, Broster and Siviter, 1980), comparing favourably with estimates of energy requirements for growth (MAFF, 1975). With low straw (< 50%) diets, the response to fish meal was less.