Profile of isoacids in rumen fluid and influence of added isoacids on in sacco dry matter disappearance of untreated and ammonia treated wheat straw

Abstract

The influence of type of diet and time after feeding on concentration of isoacids in rumen fluid of 6 fistulated sheep were investigated. The concentration of isoacids in rumen fluid was higher in diets rich in concentrate and protein (5.6) than in roughage diets (3.4) or in straw-starch-urea diets poor in native protein (highest concentration: 2.1 mmol/l rumen fluid). Feeding of roughage diet or straw-starch-urea-diet effected a significant decrease of concentration of isoacids in the rumen fluid after morning feeding, but concentrate-roughage diet, increased the isoacids-concentration. Reasons for decreased concentration of isoacids may be a shortage of corresponding amino acids and a high activity of cellulolytic microbes. Infusion of isoacids (3 g per day) in the rumen of sheep fed with a straw-starch-sugar-urea diet did not significantly influence the in sacco dry matter degradability of untreated wheat straw, but increased the dry matter loss of ammonia treated wheat straw from 16.0; 26.6; 39.4; 54.0 and 58.8% to 17.3; 29.7; 43.1; 56.3 and 63.0% after 6; 12; 24; 48 and 72 h rumen incubation time respectively. Further experiments seem to be necessary. The effect of isoacids may be expected to occur with poor quality feeds, rich in fibre low in protein and hence low in branched-chain amino acids.

Effects of isobutyrate on rumen fermentation, urinary excretion of purine derivatives and digestibility in steers

“…Liu et al digestibility in the present study is in agreement with other studies (Soofi et al 1982;Gorosito et al 1985). Flachowsky et al (1988) reported that a daily infusion of 3 g BCVFA in the rumen of sheep increased in situ DM loss of ammonia treated wheat straw by 8. 1, 11.7, 9.4, 4.3 and 7.1% after 6, 12, 24, 48 and 72 h of ruminal incubation, respectively.…”

Effects of dietary protein levels and 2‐methylbutyrate on ruminal fermentation, nutrient degradability, bacterial populations and urinary purine derivatives in Simmental steers

“…() reported that populations of total bacteria, R. albus and F. succinogenes increased with increasing dietary CP level in buffaloes. Similarly, dietary BCVFA supplementation provided essential nutrient for ruminal cellulolytic bacteria and promoted microbial growth (Cummins & Papas, ; Flachowsky et al., ). Previous studies found that populations of R. albus , R. flavefaciens , B. fibrisolvens and F. succinogenes, and activities of carboxymethyl‐cellulase and xylanase increased, but microbial protease activity decreased with isovalerate or isobutyrate supplementation (Liu et al., ; Wang et al., ).…”

“…The result confirmed the findings of previous studies that the effects of BCVFA supplementation were associated with dietary CP content and quality (Liu et al., , ; Wang et al., ). Literature demonstrated that ruminal BCVFA derived from the degradation of branched chain amino acids and could provide carbon skeleton for corresponding amino acids synthesis (Cummins & Papas, ; Flachowsky et al., ). Dietary MB supplementation could reduce the degradation of branched chain amino acids, thus the utilization of protein improved.…”

“…The branched-chain volatile fatty acids (BCVFA), including isobutyrate, isovalerate and 2-methylbutyrate (MB), are produced from the degradation of branched-chain amino acids in the rumen (Flachowsky, Matthey, Ochrimenko, & Schneider, 1988). Ruminal BCVFA can provide carbon skeleton for the synthesis of valine, isoleucine and leucine and is an important growth factor for most ruminal cellulolytic bacteria (Cummins & Papas, 1985;Flachowsky et al, 1988).…”

“…The branched-chain volatile fatty acids (BCVFA), including isobutyrate, isovalerate and 2-methylbutyrate (MB), are produced from the degradation of branched-chain amino acids in the rumen (Flachowsky, Matthey, Ochrimenko, & Schneider, 1988). Ruminal BCVFA can provide carbon skeleton for the synthesis of valine, isoleucine and leucine and is an important growth factor for most ruminal cellulolytic bacteria (Cummins & Papas, 1985;Flachowsky et al, 1988). Previous studies found that ruminal fermentation, neutral detergent fibre (NDF) degradability, cellulolytic bacterial populations and activities of caboxymethyl-cellulase, xylanase and β-glucosidase increased with BCVFA supplementation in steers (Liu et al, 2008(Liu et al, , 2009Wang et al, 2012).…”