In situ rumen degradation of amino acids from different feeds corrected for microbial contamination

Abstract

-Variations of the amino acid profile produced by rumen actions were established for fish meal (FM), corn grain (CG), corn gluten feed (GF), dehydrated beet pulp (DBP), and lucerne hay (LH), using the nylon bag technique. The effects of degradation of soluble or insoluble proteins were measured by rumen incubations at 0 h (washout value) and 16 h, respectively. Rumen incubations were performed on four cannulated wethers and the microbial contamination of incubated residues was corrected using a continuous 15 N-intraruminal infusion and solid associated bacteria isolates as the reference sample. The results showed that rumen degradation of both soluble and insoluble proteins produced changes in the amino acid profile, which were not uniform among feeds. Differences between feed and insoluble protein amino acid composition were limited for FM and DBP, important for GF and LH, and intermediate for CG. Differences between insoluble and undegraded protein amino acid composition were also limited for FM, GF, DBP, and LH and important in CG. The results showed that the amino acid profile in the undegraded protein and in the whole feed should be close for FM, DBP and LH. On the contrary, in CG, important variations are expected, since both solubility and degradability effects produced changes with the same tendency for most of the essential amino acids. In particular, our results showed a great decrease in the lysine content of the undegraded protein, which increases the lysine deficiency of this feed. This decrease of lysine was also evidenced in GF.rumen degradation / amino acid profile / microbial contamination / 15 N Résumé -Dégradation ruminale in situ des acides aminés de différents aliments, corrigée par la contamination microbienne. Les variations produites par les actions ruminales sur le profil des acides aminés de la farine de poisson (FP), du grain de maïs (GM), du gluten feed de maïs (GF), de la pulpe de betterave deshydratée (PBD) et du foin de luzerne (FL) ont été déterminées par la J. González et al. 254

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

“…() found the individual AA from different protein source was selectively removed by the rumen micro‐organisms, especially for Trp, Arg, His and Lys. In this study, we found a relative increase in Lys of RUP in corn stover and rice straw as well as the three TMR diets, which is contrary to the finding that a significant decrease in the Lys content of RUP was found in several concentrates (González, Centeno, Lamrani, & Rodríguez, ). The observed Lys in alfalfa hay stayed constant after rumen degradation (Erasmus et al., ; González et al., ), which might be attributed the Lys in protein structure of alfalfa hay was distributed uniformly.…”

“…(), who also used published values for microbial AA composition. Many studies have corrected for microbial contamination using the specific technique of 16 hr incubated feeds with the in situ method (Edmunds et al., ; Erasmus et al., ; González, Centeno, Morujo, Faría‐Mármol, & Martínez, ; González et al., ), and these studies showed more accurate AA profiles of the RUP after this correction. However, limited research has focused on the comparison between profiles that were either corrected or not corrected for microbial contamination.…”

Effect of extent and rate of wilting on nitrogen components of grass silage

“…Clear treatment effects on the AA composition of the silages were observed. However, with the knowledge that AA composition of most feeds changes during rumen incubation (Erasmus et al ., ; Van Straalen et al ., ; Von Keyserlingk et al ., ; González et al ., ), these ensiling‐related changes will only be discussed briefly. The mean AA content of sample CP was 695 ± 31 g kg −1 .…”

In situ ruminal amino acid degradability of green and ensiled Italian rye-grass according to particle transit model and microbial contamination correction

“…Differences in degradability observed among AA (or the resultant changes between the AA profiles of the feed and its undegraded protein) should be due to simultaneous differences between the feed proteins in AA composition and resistance to the rumen degradation (González et al, 2001). The ensiling of GRG leads to a reduction of the AA content as well as to large changes in the AA profile (Table 2).…”