Forage:Concentrate Ratio Effects on In Vivo Digestibility and In Vitro Degradability of Horse's Diet.
Authors: Zicarelli Fabio, Tudisco Raffaella, Lotito Daria, Musco Nadia, Iommelli Piera, Ferrara Maria, Calabrò Serena, Infascelli Federico, Lombardi Pietro
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary This Italian research team investigated how varying forage-to-concentrate (F:C) ratios—ranging from 90:10 through to 50:50—affect both the actual digestibility of equine diets and their fermentation behaviour in the laboratory. Using five successive dietary treatments based on hay, straw, barley and oats, they measured in vivo digestibility in horses whilst simultaneously validating the Gas Production Technique (GPT) using faecal inoculum to predict in vitro degradability. Interestingly, whilst no significant differences in apparent digestibility emerged between the diets despite their markedly different concentrate inclusion, the in vitro fermentation patterns revealed that diets containing 22% concentrate or higher showed consistent gas production curves with robust microbial activity in the early incubation phase, with gas production correlating strongly to volatile fatty acid (VFA) production. The close relationship between gas output and VFA suggests that equine caecal fermentation follows similar metabolic pathways to ruminant digestion, indicating that GPT using faecal inoculum could become a standardised tool for rapid nutritional assessment of equine feeds. However, practitioners and nutritionists should note that whilst this technique shows promise for predicting fermentation characteristics, further refinement is needed before GPT can reliably replace traditional digestibility trials, particularly for rations at the higher forage end of the spectrum.
Read the full abstract on PubMed
Practical Takeaways
- •Forage:concentrate ratios between 50/50 and 90/10 produce similar digestibility outcomes in horses, offering flexibility in diet formulation based on other management considerations
- •The Gas Production Technique with fecal inoculum provides a rapid, practical laboratory tool for evaluating feed quality for horses without requiring rumen fluid
- •Digestibility testing should be performed before major dietary changes to confirm net energy content, as this varies by individual feed composition
Key Findings
- •In vivo digestibility showed no significant differences across five diets with F:C ratios ranging from 90/10 to 50/50
- •In vitro gas production curves for four of five diets (2, 3, 4, 5) demonstrated similar fermentation patterns with active fecal microbiota in early incubation hours
- •Strong correlation between gas production and volatile fatty acid (VFA) production suggests equine cecal fermentation follows similar metabolic pathways to rumen fermentation
- •Gas Production Technique using equine fecal inoculum is a viable method for evaluating nutritional characteristics of equine feedstuffs