Evaluating the Effects of Some Selected Medicinal Plant Extracts on Feed Degradability, Microbial Protein Yield, and Total Gas Production In Vitro

SIMPLE SUMMARY: Ruminant animals are major producers of animal protein, and their uniqueness in utilizing unconventional feed resources cannot be overemphasized. In the tropical environment, most of the unconventional feeds available for this class of animals are of low quality and are characterized by high structural carbohydrates which lack adequate fermentable carbohydrates and nitrogen composition, a factor of crude protein. Feeding poor-quality forage has been linked to higher methane production from ruminants, and improving the rumen fermentation of these poor forages can improve animal performance and reduce methane emission. Many strategies have been employed in recent times, and the most successful is the use of antibiotics, but there is a campaign against the use of antibiotics. Other strategies such as the use of natural products such as plant extracts rich in antibiotics and phytochemicals have been exploited. This study evaluates the effect of phytochemical-rich plant extracts on fermentation parameters in vitro, and the results were promising. ABSTRACT: This study evaluates the effect of 22 crude ethanolic plant extracts on in vitro rumen fermentation of Themeda triandra hay using monensin sodium as a positive control. The experiment was run independently three times at 16 and 48 h of incubation periods using the in vitro gas production techniques. Fermentation parameters were determined at both hours of incubation. Plant extracts influenced gas production (GP) in a varied way relative to control at both hours of incubation, and GP is consistently highly significant (p < 0.0001) at 16 and 48 h. Microbial protein yield (MY) was not significantly affected at 16 h (p > 0.05), but it was at 48 h (p < 0.01). Higher MY was recorded for all treatments except for A. sativum and C. intybus at the early incubation stage (16 h) relative to 48 h of incubation. Compared to the control group at 48 h, all plant extracts have higher MY. After 48 h of incubation, the result shows that plant extracts have an effect on fermentation parameters determined; ruminal feed degradation, gas production, microbial protein yield, and partitioning factor in varied manners. All the plant extracts improve the MY which is the major source of amino acids to ruminants and has significant importance to animal performance. C. illinoinensis, C. japonica, M. nigra, P. americana, C. papaya, and A. nilotica (pods) were the most promising plant extracts, but further study is recommended to validate the in vitro observation in vivo.