Importance of dietary amino acids in the nutrition of grazing ruminants

摘要

The value of proteins from corn (Z), menhaden fishmeal (M), blood meal (B), cotton seed meal (C) or feather meal (F) as supplements for heifers grazing either bermudagrass (Cynodon dactylon) or annual ryegrass (Lolium multiflorum) was evaluated. Flowof digesta and protein fractions was estimated by constant infusion of two rare earth acetates and Na_2~(35)SO_4 into the rumen and analysis of duodenal and rectal digesta. The experimental design for the bermudagrass experiment involved supplements of Z,(8% crude protein, CP) or 34% CP supplements formulated with Z plus M, F and C fed twice daily in a 2 period replicated design. Heifers grazing ryegrass pastures received supplements Z, M, F, C, blood meal (B), a cottonseed meal-urea block (P) or a mineral control in a 7 by 3 Youden square, Digesta entities determined included true protein (TP, trichloroacetic insoluble, Lowry reactive), microbial protein (MP) and UIP as TP-MP.