Models for estimating digesta passage kinetics in the gastrointestinal tract of the horse.

The research focuses on developing mathematical models to understand the digesta passage kinetics, that is, the process and speed of digestion, in horses’ gastrointestinal tract. Using fecal samples from horses fed with different types of oats and hay, the models compared the passage kinetics of these two types of food.

Study Design

• Four Norwegian Cold-blooded trotters were utilized for this experiment. These horses, with approximately 500kg body weight each were provided with a specific diet that included Cr-mordanted Hay and Yb-marked oats.
• Each horse was given 2kg of hay and 1kg of oats that were processed in different ways including ground, pelleted, extruded, or micronized varieties. The administration of feeds was done in a structured way following a 4×4 Latin square design.
• Every different kind of oats was given on separate days after a 5-day adaptation period. This cumulative process was conducted to assess how different types of oats may influence the gastrointestinal tract functioning.

Data Collection and Analysis

• After administration of the marker dose, fecal samples were collected at various hours extending up to 52 hours. This helped the researchers to get an accurate timeline of the digestion process.
• Subsequently, the samples were analyzed for their Cr and Yb content. The gathered data were then utilized to devise 1- and 2-compartment nonlinear passage models and algebraic models.
• Among the tested models, the 1-compartment G4 model and the 2-compartment G4G1 model illustrated a potent fit to the observed excretion curves. These curves were assessed through minimal mean square error and SE.

Findings and Implications

• The research found that the excretion curves for hay (Cr) and oats (Yb) showed a significant similarity, indicating no notable difference in retention time between hay and oats in the horse.
• This suggests that the processing method of the oats does not significantly alter the digestion kinetics in horses.
• The mixing compartments in the horse, assumed to be the cecum or both the cecum and the right ventral and dorsal segments of the colon, played a pivotal role in digestion. However, further research is required in this area to draw a concrete conclusion.