The amino acid composition of rumen-undegradable protein: A comparison between forages

Abstract

The objective of this study was to improve knowledge regarding the amino acid profile of the insoluble portion of ingested forage escaping rumen degradation. Six forage categories were analyzed. Categories varied in botanical composition and each contained 2 samples. Samples within categories were derived from the same parent material but differed in harvest, maturity, or conservation type. The rumen-undegradable protein of all forages was measured by incubation for 16h in the rumen of 3 nonlactating cows. All residues were corrected for microbial colonization. The AA profile of the residue was different to the original profile. Degradation trends of individual AA, in terms of increase or decrease relative to the original concentration, were similar between all forages. The AA profiles of forage residues, both within and between categories, were more similar to each other than to their respective original profile. This information may aid in improving the accuracy of estimating postruminal AA supply from forages while decreasing the number of samples required to be analyzed.

Amino acid profiles of rumen undegradable protein: a comparison between forages including cereal straws and alfalfa and their respective total mixed rations

“…The findings of the present study suggest that not only most of the analysed AAs of alfalfa hay, corn stover and rice straw differ between originals and residues, but also the TMR‐based diets showed time effects of rumen degradation on AA profiles. This is in agreement with previous studies; different forages were studied comparatively, with focus on the different forage categories, and have shown that AA composition changes in forages after rumen degradation (Edmunds et al., ). Generally, the AA composition from RUP of feed varies depending on its source (Seymour, Polan, & Herbein, ), and thus, the focus needs to be on specific individual AA.…”

“…Generally, the AA composition from RUP of feed varies depending on its source (Seymour, Polan, & Herbein, ), and thus, the focus needs to be on specific individual AA. The data from this study demonstrated that the individual AA profile could be changed due to the rumen degradation, which is strongly supported by many previous studies (Edmunds et al., ; Erasmus et al., ; Mjoun et al., ; Von Keyserlingk et al., ). Gao et al.…”

“…Obtaining reliable and accurate values with this method requires correction for microbial contamination (Edmunds et al., ; Krawielitzki, Schmidt, Voigt, Kowalczyk, & Gabel, ). The method used to correct AA profiles of in situ residues for microbial attachment to feed particles was performed according to Edmunds et al.…”

“…The method used to correct AA profiles of in situ residues for microbial attachment to feed particles was performed according to Edmunds et al. (). Briefly, microbial attachment (MA: g of residue crude protein (CP)/100 g) was estimated following the exponential equation of Krawielitzki et al.…”

“…However, Edmunds et al. () found that the AA profile of forage diets within and between categories was more similar to each other than to their respective original profile. However, other studies have shown that the AA profile of feedstuff does indeed differ from each other and their respective original profile after rumen degradation (Maxin, Ouellet, & Lapierre, ; Mjoun, Kalscheur, Hippen, & Schingoethe, ).…”