Proanthocyanidins Modulate Rumen Enzyme Activities and Protein Utilization In Vitro

Area of Science:

• Animal Nutrition
• Plant Biochemistry
• Rumen Microbiology

Background:

• Proanthocyanidins (PAs) are plant secondary metabolites with potential effects on ruminant digestion.
• Understanding PA structure-activity relationships is crucial for optimizing forage utilization.

Purpose of the Study:

• To investigate the effects of proanthocyanidin fractions from Anogeissus pendula (AP) and Eugenia jambolana (EJ) leaves on in vitro ruminal enzyme activity and Rubisco solubilization.
• To correlate these effects with the molecular structure of the extracted PAs.

Main Methods:

• Extraction of six PA fractions from AP and EJ leaves using varying solvent polarities (methanol-water, acetone-water, distilled water).
• In vitro assessment of PA effects on ruminal enzymes (transaminases, cellulase, glutamate dehydrogenase, protease) and Rubisco solubilization from wheat straw and berseem hay.
• Supplementation trials with AP and EJ leaves to evaluate microbial protein efficiency.

Main Results:

• All PA fractions significantly inhibited ruminal transaminase activities.
• AP-50 and EJ-50 fractions inhibited R-cellulase activity.
• Most fractions inhibited R-glutamate dehydrogenase, while protease activity decreased significantly.
• Rubisco solubilization was higher with AP and EJ leaves compared to control forages.
• Supplementation with AP and EJ leaves increased protein solubilization, with AP showing greater microbial protein efficiency.

Conclusions:

• Proanthocyanidins from E. jambolana exhibit stronger inhibitory effects on rumen enzymes.
• Proanthocyanidins from A. pendula demonstrate higher protein solubilization potential.
• PAs from both species can modulate rumen enzyme activity, suggesting potential for improved protein and fiber utilization in ruminants.