TY - JOUR
T1 - Fermentation behaviour of the nylon bag washout and degradable fractions determined with the gas production technique
AU - Cone, J.W.
AU - van Gelder, A.H.
AU - Chai, W.Z.
PY - 2006
Y1 - 2006
N2 - Most feed evaluation systems for ruminants are based on data obtained with the nylon bag technique. This technique divides the samples in a washout (W) fraction, passing the pores of the nylon gauze of approximately 40 ¿m, and a degradable (D) fraction, unable leaving the bags unfermented. Generally, it is assumed that the W-fraction is immediately and completely fermented in the rumen. Experiments were conducted to determine the percentage fast and moderate fermentable components in both the W- and the D-fraction, using the gas production technique. Ten starchy feed ingredients were separated in vitro by filtration over a nylon gauze of 40 ¿m. Gas production profiles were recorded of the obtained W- (mean 223 g/kg) and D-fractions (mean 777 g/kg). The results show that on average only 376 g/kg of the W-fraction, high in starch, can be regarded as fast fermentable and 624 g/kg as moderate fermentable. The moderate fermentable proportion showed a fermentation behaviour comparable with the D-fraction. On the contrary, also 143 g/kg of the D-fraction could be regarded as fast fermentable. The results obtained with the D-fractions obtained by an in vitro method were confirmed with D-fractions obtained according to the nylon bag protocol, using a washing machine with running tap water. It was concluded that the major part of the in situ W-fraction is not immediately fermentable and actually is a washout part of the D-fraction.
AB - Most feed evaluation systems for ruminants are based on data obtained with the nylon bag technique. This technique divides the samples in a washout (W) fraction, passing the pores of the nylon gauze of approximately 40 ¿m, and a degradable (D) fraction, unable leaving the bags unfermented. Generally, it is assumed that the W-fraction is immediately and completely fermented in the rumen. Experiments were conducted to determine the percentage fast and moderate fermentable components in both the W- and the D-fraction, using the gas production technique. Ten starchy feed ingredients were separated in vitro by filtration over a nylon gauze of 40 ¿m. Gas production profiles were recorded of the obtained W- (mean 223 g/kg) and D-fractions (mean 777 g/kg). The results show that on average only 376 g/kg of the W-fraction, high in starch, can be regarded as fast fermentable and 624 g/kg as moderate fermentable. The moderate fermentable proportion showed a fermentation behaviour comparable with the D-fraction. On the contrary, also 143 g/kg of the D-fraction could be regarded as fast fermentable. The results obtained with the D-fractions obtained by an in vitro method were confirmed with D-fractions obtained according to the nylon bag protocol, using a washing machine with running tap water. It was concluded that the major part of the in situ W-fraction is not immediately fermentable and actually is a washout part of the D-fraction.
KW - protein degradability
KW - rumen
KW - kinetics
U2 - 10.1016/j.anifeedsci.2005.09.008
DO - 10.1016/j.anifeedsci.2005.09.008
M3 - Article
VL - 127
SP - 319
EP - 326
JO - Animal Feed Science and Technology
JF - Animal Feed Science and Technology
SN - 0377-8401
IS - 3-4
ER -