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Effects of amount of intake and stage of forage maturity on urinary allantoin excretion and estimated microbial crude protein synthesis in the rumen of steers
Author(s) -
Südekum K.H.,
Brüsemeister F.,
Schröder A.,
Stangassinger M.
Publication year - 2006
Publication title -
journal of animal physiology and animal nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.651
H-Index - 56
eISSN - 1439-0396
pISSN - 0931-2439
DOI - 10.1111/j.1439-0396.2005.00574.x
Subject(s) - allantoin , rumen , forage , excretion , zoology , biology , fodder , dry matter , maturity (psychological) , chemistry , food science , agronomy , biochemistry , fermentation , psychology , developmental psychology
Summary Using ruminally cannulated steers, we investigated how urinary allantoin excretion was related to variations in feed intake and stage of forage maturity. Further, different approaches were compared for predicting ruminal microbial crude protein (MCP) synthesis and its efficiency. Experimental diets were arranged in a replicated 3 × 3 Latin square design (experiment 1) and a 4 × 4 Latin square design (experiment 2). In experiment 1, a mixed diet [forage to concentrate, 68:32 on a dry matter (DM) basis] was fed at three intake levels corresponding to 1, 1.5 and 2 times maintenance energy requirements. In experiment 2, four silage‐based diets were fed based on perennial ryegrass ( Lolium perenne L. ), which was harvested at four maturity stages. Both experiments demonstrated the influence of diet on microbial growth rate and by this on efficiency of MCP synthesis, although the magnitude of the effects differed between approaches used for estimating MCP. Linear functions satisfactorily characterised the relationship between urinary allantoin excretion ( y ) and digestible organic matter (OM) intake ( x , kg/day; experiment 1: y = 7.94 + 17.34 x ; R 2 = 0.785) or intake of OM effectively degraded in the rumen ( x , kg/day; experiment 2; y = 22.32 + 5.93 x ; R 2 = 0.695). Urinary excretion of allantoin permitted a semi‐quantitative prediction of MCP synthesis: ranking of diets and magnitude of changes in MCP synthesis were reflected.