The apparent digestibility of crude protein by the ruminant: I. A synthesis of the results of digestibility trials with herbage and mixed feeds

Abstract

The apparent digestibility of crude protein by cattle and sheep of different breeds and types, both temperate and tropical, has been studied by means of an analysis of the results of feeding trials with herbages and mixed feeds in many parts of the world. No matter whether herbages or mixed feeds are used the digestibility coefficient (y) is shown to be related to the percentage crude-protein content of the feed (x) by means of an expression of the form y = a + b log x. The particular equation y= 70 log x − 5 is shown to give a reasonable fit of all the available data.The digestibility of crude protein in the feed is shown to increase very rapidly at low protein levels (from about 2 to 9%), and there after it rises more slowly as the crude-protein content increases.There is close agreement between the equations for herbage fed alone and for mixed feed which suggests that the total percentage of crude protein in the feed, irrespective of its nature, determines the digestibility of the protein.

Nutrient Digestibility of Forage and Nonforage Rations in the Ruminant

“…Digestible N was regressed upon total N (P < .01) (table 2), and the results essentially agreed with the nonforage (1) and forage (3) data. Similar correlations (P < .01) have been obtained for forages (6,7,9,17) and for lower fiber feeds by Preston (11). True N digestibility and metabolic fecal N fractions were 86 and 1.9 percent (table 2), respectively, in contrast to those obtained from forage (87 and 2.8 percent) and nonforage (100 and 3.9 percent) (1) data.…”

Futteraufnahme und Nährstoffverdaulichkeit bei der Milchkuh während und nach energetischer Überversorgung

“…Bei hoherem Proteingehalt bzw. weiterem EiweiR-Energie Verhaltnis steigt jedoch die scheinbare N-Verdaulichkeit an, da sich der Anteil des endogenen Kotstickstoffs am gesamten Fakal-N vermindert und der ausgeschiedene UberschuR-NH,-N aus dern Pansen als verdaut gerechnet wird (GLOVER et al 1957;HOLTER und REID 1959;GORDON und FORBES 1970;SAELZER und KAUFMANN 1974;ROHRMOSER und KIRCHGESSNER 1982;ROHRMOSER et al 1984;KREUZER und KIRCHGESSNER 1985 a). Die enge Kopplung der Kot-N-Exkretion an die T-Aufnahrne (HIRO-NAKA et al 1970;STALLCUP et al 1975) sowie der reduzierende Effekt des erhohten Energieniveaus (SCHIEMANN et al 1971;EKERN 1972; VAN DER HONING 1981COLUCCI et al 1982 (siehe FLATT et al 1969 b;SCHIEMANN et al 1971;EKERN 1972;LINDGREN 1981; VAN DER HONING et al 1981COLUCCI et al 1982) wird ein ahnlicher oder hoherer Wert beschrieben, wahrend bei 13 '/0-15~/0 Rohprotein in der Ration von N-Verdauungsquotienten zwischen 55% und 62% berichtet wird HOLTER et al 1982;TELLER et al 1983;ROHRMOSER et al 1984;KREUZER und KIRCHGESSNER 1985a).…”

Evaluation of Forage Crops by Chemical Analysis. A Critique1

“…The requirement for animals is for digestible crude protein rather than for total crude protein but as the digestion coefficient for crude protein is positively and significantly correlated with the percentage of crude protein (13,27), • the latter does very well as a measure of quality. Incidentally, there is no reliable chemical method for measuring the protein that is digestible by ruminants.…”