Effects of pH, temperature and osmolality on the level and composition of soluble N in feedstuffs for ruminants

A modified rinsing method for the determination of the S, W–S and D + U fraction of protein and starch in feedstuff within the in situ technique

“…The difference between both methods was smaller for the higher shaking speeds of the modified method. Differences between the S fractions of N for both methods were also observed for several feeds, presumably related to differences in solvent, which is in line with the previous observations (de Jonge et al, 2009). Differences between the W-S fractions for N found by both methods are the result of the combination of differences found for the other fractions (i.e., S and D 1 U).…”

“…First, two methods are used that are not equal in solubility conditions, which can lead to systematic differences in determining S and W fractions. Especially for N, these differences can lead to inaccurate and sometimes even negative values for the W-S fraction (Madsen and Hvelplund, 1994;de Jonge et al, 2009). Second, the W-S fraction is calculated by difference, which makes it impossible to verify the accuracy of the method based on total recovery.…”

“…These modifications involve a closed system and standardised conditions enabling the separation and estimation of all fractions using one rinsing method and the replacement of water by a buffer solution that better mimics the rumen conditions (de Jonge et al, 2009). The objectives of this study were to develop and test this modified method and to characterise the isolated W-S fraction.…”

Precipitation of proteins in the rumen fluid using tungstic and trichloracetic acid after feeding sheep thermally treated or untreated soybean meal

“…Such underestimation was also observed in vivo by Choi et al (2002). More recently, degradation characteristics of different proteins sources were shown to be dependent of different reaction conditions to obtain soluble N content of feeds like pH, temperature and osmolality (De Jonge et al, 2009). There is a need to find standardized in vivo method to assess routinely the degradation products of dietary protein in the rumen of different feeds.…”

Application of in vitro digestibility methods in aquaculture: constraints and perspectives

“…For example, in many cases, only the intestinal stage of the digestion but not the gastric phase is simulated; such an approach may be suitable in the case of decapod crustaceans, but incorrect for many fish species with a functional stomach. It has been demonstrated that stomach digestion of protein has a remarkable effect on further processing due to the effect of both acid pH, with affects protein solubility (de Jonge et al 2009) and pepsin (Alarc on et al 2002). Also, stomach digestion has also been shown to inactivate some trypsin inhibitors present in protein-rich plant ingredients (Krogdahl & Holm 1981;Alarc on et al 2001).…”