A new nordic structure evaluation system for diets fed to dairy cows: a meta analysis

TY - CHAP

T1 - A new nordic structure evaluation system for diets fed to dairy cows

T2 - a meta analysis

AU - Nørgaard, Peder

AU - Nadeau, E.

AU - Randby, Å.T.

PY - 2010

Y1 - 2010

N2 - The overall aim was to establish a model for predicting chewing index (CI) values for ranking the fibrousnesses of feeds fed to dairy cows within the Nordic Chewing index system. The CI values are predicted as the sum of the eating (EI) and ruminating time index (RI) values. The EI values are assumed to be proportional with the NDF content and a particle size factor through the porportionality factor kEI. The RI values are assumed to be proportional with the NDF content, a particle size factor and a hardness factor through the proportionality factor kRI. The kEI, kRI values and the kEI/kRI ratios were parameterized as the mean eating (mETf), mean ruminating time (mRTf) per intake of forage NDF (NDFIf) and themETf/mRTf ratio by a Meta analysis of 75 published values from cattle fed three types of unchopped forages with or without supplementation with concentrates. The intake of NDF from ground concentrate (NDFIc) and rolled barley (NDFIRB) was related to NDFIf in the models, which included effects of BW, NDFIf/BW, NDFIRB/BW, NDFIRB/NDFIf, NDFIc/NDFIf, DM content of silage, interaction between forage type and physiological state of the cattle, method for recording chewing, and with studies as random effect for ruminating time. The mRTf value per kg forage NDF decreased at increased BW and DNFIf/BW. The mETf value increased at increasing BW and at decreasing DM contents of grass silage. Intake of NDF from rolled barley stimulated ruminating time by 3/4 of the stimuli from DNFIf. The mETf/mRTf ratio, the mETf and mRTf values of grass silage fed to a standard cow, BW=625 kg, 0.7% NDFIf per kg of BW were predicted to 0.41 (min/min), and 41 and 109 (min/kg NDF), respectively.

AB - The overall aim was to establish a model for predicting chewing index (CI) values for ranking the fibrousnesses of feeds fed to dairy cows within the Nordic Chewing index system. The CI values are predicted as the sum of the eating (EI) and ruminating time index (RI) values. The EI values are assumed to be proportional with the NDF content and a particle size factor through the porportionality factor kEI. The RI values are assumed to be proportional with the NDF content, a particle size factor and a hardness factor through the proportionality factor kRI. The kEI, kRI values and the kEI/kRI ratios were parameterized as the mean eating (mETf), mean ruminating time (mRTf) per intake of forage NDF (NDFIf) and themETf/mRTf ratio by a Meta analysis of 75 published values from cattle fed three types of unchopped forages with or without supplementation with concentrates. The intake of NDF from ground concentrate (NDFIc) and rolled barley (NDFIRB) was related to NDFIf in the models, which included effects of BW, NDFIf/BW, NDFIRB/BW, NDFIRB/NDFIf, NDFIc/NDFIf, DM content of silage, interaction between forage type and physiological state of the cattle, method for recording chewing, and with studies as random effect for ruminating time. The mRTf value per kg forage NDF decreased at increased BW and DNFIf/BW. The mETf value increased at increasing BW and at decreasing DM contents of grass silage. Intake of NDF from rolled barley stimulated ruminating time by 3/4 of the stimuli from DNFIf. The mETf/mRTf ratio, the mETf and mRTf values of grass silage fed to a standard cow, BW=625 kg, 0.7% NDFIf per kg of BW were predicted to 0.41 (min/min), and 41 and 109 (min/kg NDF), respectively.

KW - Former LIFE faculty

KW - chewing index

KW - mean eating time

KW - mean ruminating time

KW - intake forage NDF

M3 - Book chapter

SN - 078-90-8686-156-9

SP - 112

EP - 120

BT - Modelling nutrient digestion and utilisation in farm animals

A2 - Sauvant, D.

A2 - Van Milgen, J.

A2 - Faverdin, P.

A2 - Friggens, N.

PB - Wageningen Academic Publishers

ER -