Effects of incorporating plantain, chicory, and alfalfa into a ryegrass-based diet on in vitro gas production and fermentation characteristics

Abstract

Objective: The objective of these experiments was to determine how altering the proportion of ryegrass (Lolium perenne L.) to chicory (Cichorium intybus L.), alfalfa (Medicago sativa L.), or plantain (Plantago lanceolata L.) or a mixture (equal parts DM of chicory, alfalfa, and plantain) affects the in vitro fermentation rates and formation of fermentation products. Materials and Methods: In vitro experiments were conducted using the ANKOM RF gas production modules (ANKOM). Experiment 1 examined increasing inclusion level (0, 50, 100%) of chicory, plantain, or alfalfa with ryegrass, and Exp. 2 examined increasing inclusion level (0, 25, 50, 75, 100%) of ryegrass to a mixture (equal parts DM of chicory, plantain, and alfalfa). Results and Discussion: In Exp. 1, there was a positive linear effect for 24-h gas production per gram of DM as inclusion increased for chicory (P < 0.01) and plantain (P < 0.01). A negative linear relationship was detected for ammonia (NH₃) and branched-chain VFA with increased level of inclusion of plantain (P < 0.01) and chicory (P < 0.01). In Exp. 2, there were linear (P < 0.01), quadratic (P < 0.01), and cubic (P < 0.01) effects on both the asymptote of the gas production curve (mL/g of DM) and the fractional rate of gas production (%/h) with increasing mixture inclusion. There was a linear decrease in the total VFA composed of iso-butyrate (P < 0.01) and iso-valerate (P < 0.01) as the level of chicory, plantain, and alfalfa inclusion increased. Implications and Applications: Incorporating greater levels of chicory; plantain; or a mixture of chicory, plantain, and alfalfa with ryegrass increased gas production and reduced NH₃ and branched-chain VFA in rumen fluid, which could imply a greater nutrient supply from the rumen to the host animal. Further research is required to evaluate whether these results translate to in vivo benefits on animal performance and reductions of urinary N excretion.