Nitrogen and Energy Supplements for Low Quality Roughages

The two approaches often are complementary, as treatments which increase intake or digestibility may generate a need for additional nutrients to supply the needs of rumen bacteria as well as of the host animal. In these papers we have considered nitrogen (N) requirements of rumen bacteria and of the animal, in animals fed untreated and chemically-treated forages of low nutritive value. The reason for considering both bacterial and animal requirements is because all proteins contain rumen-degradable and by-pass fractions, the relative significance of which is likely to vary with the circumstances in which it is fed. Proteins also provide supplementary energy and minerals which may increase the edibility of roughages. Thus, effects of protein supplements may be attributed to one or more of the following factors:(i) slow release of N in the rumen (ii) increase in the proportion of nutrients absorbed as essential amino acids (iii) supplementary energy, including gluconeogenesis (iv) stimulatory effects on intake.