Effects of concentrate-to-forage ratios and 2-methylbutyrate supplementation on ruminal fermentation, bacteria abundance and urinary excretion of purine derivatives in Chinese Simmental steers

SUMMARYThe current experiment was conducted to evaluate the effects of different dietary protein levels and rumen-protected folic acid (RPFA) supplementation on ruminal fermentation, microbial enzyme activity, bacterial populations and urinary excretion of purine derivatives (PD) in growing beef steers. Low-protein (LP) or high-protein (HP) diets were fed to eight ruminally cannulated first-generation cross-bred (Blonde d'Aquitaine × Simmental) beef steers with or without RPFA supplementation. Steers were fed a total mixed ration, and dietary concentrate to maize silage ratio was 50 : 50 (dry matter (DM) basis). No interaction between dietary crude protein (CP) levels and RPFA supplementation was observed during the experiment. Ruminal pH was unaffected by RPFA supplementation, but decreased with increasing dietary CP levels. Ruminal total volatile fatty acid concentration increased with increasing dietary CP levels or RPFA supplementation. Molar proportion of acetate increased with RPFA supplementation, but tended to decrease with increasing dietary CP levels. The proportion of propionate decreased with RPFA supplementation, but was unaffected by dietary CP levels. As a result, the acetate to propionate ratio increased with RPFA supplementation, but tended to be lower for the HP diets than the LP diets. Ammonia-nitrogen content decreased with RPFA supplementation, but increased with increasing dietary CP levels.In situruminal degradability of maize straw and concentrate increased with increasing dietary CP levels or RPFA supplementation. Microbial enzyme (carboxymethyl-cellulase, cellobiase, xylanase, pectinase,α-amylase and protease) activity, bacterial populations (Ruminococcus albus,Ruminococcus flavefaciens,Butyrivibrio fibrisolvens,Prevotella ruminicola,Fibrobacter succinogenesandRuminobacter amylophilus) and urinary PD excretion increased with increasing dietary CP levels or RPFA supplementation. The current study showed that increasing dietary CP levels from 109·1 to 130·7 g/kg DM or supplementing 75 mg RPFA improved ruminal fermentation and microbial protein synthesis by increasing bacterial population and microbial enzyme activity.

Download Full-text

Sugars versus starch as supplements to grass silage: Effects on ruminal fermentation and the supply of microbial protein to the small intestine, estimated from the urinary excretion of purine derivatives, in sheep

Journal of the Science of Food and Agriculture ◽

10.1002/jsfa.2740630204 ◽

1993 ◽

Vol 63 (2) ◽

pp. 189-194 ◽

Cited By ~ 75

Author(s):

David G. Chamberlain ◽

Stuart Robertson ◽

Jai-Jun. Choung

Keyword(s):

Small Intestine ◽

Urinary Excretion ◽

Ruminal Fermentation ◽

Microbial Protein ◽

Purine Derivatives ◽

Grass Silage

Download Full-text

Effect of crude protein concentration on urinary excretion of purine derivatives in growing heifers fed concentrate and barley straw on an ad libitum basis

Proceedings of the British Society of Animal Science ◽

10.1017/s1752756200002441 ◽

1999 ◽

Vol 1999 ◽

pp. 89-89

Author(s):

M. Devant ◽

J. F. Pérez ◽

J. Plaixats ◽

A. Ferret ◽

G. Caja

Keyword(s):

Protein Synthesis ◽

Urinary Excretion ◽

Barley Straw ◽

Ruminal Fermentation ◽

Microbial Protein ◽

Purine Derivatives ◽

Factors Affecting ◽

Microbial Protein Synthesis ◽

Ad Libitum ◽

Soya Bean Meal

The amount and source of nitrogen required to optimize microbial protein synthesis has been widely discussed in the literature. However, information available on factors affecting microbial protein synthesis in young heifers fed high concentrate diets is limited. Our objective was to study the effect of CP concentration on ruminal fermentation and urinary excretion of purine derivatives, used as an index of microbial yield, in heifers fed concentrate and barley straw, both ad libitum, from 100 to 230 kg LW.Ten crossbreed beef heifers (101±4.5 kg LW), of which 6 where ruminally cannulated, were individually penned and randomly offered (115% of previous day consumption) a concentrate (14%, L or 17%, H) and barley straw diet once daily. Concentrates (H and L) were composed of ground corn (32; 38%), barley (27%), cassava (17%) and sunflower meal (5.8%) and soya bean meal included either at 16% or 9%, respectively.

Download Full-text