Diet composition influences equine large intestinal motility as measured by transcutaneous ultrasound.

Overview

• This study investigated how different diets influence the movement (motility) of the large intestine in healthy horses, using ultrasound to measure contraction frequency at specific locations in the large colon.
• The research compared horses fed either a complete pelleted diet or Coastal Bermudagrass hay with supplemental pellets, assessing intestinal contractions after feeding to understand dietary effects on gut motility.

Study Design and Methods

• Subjects: 12 American Quarter Horses participated in a prospective crossover study, meaning each horse experienced both diet treatments in sequence.
• Diets:
  • Complete pelleted diet fed at 1.35% of body weight per day
  • Coastal Bermudagrass hay fed at 2% of body weight daily, supplemented with 0.5% to 0.7% BW of complete pelleted feed
• Feeding Period: Each diet was provided for 13 days before measuring intestinal motility, allowing sufficient adaptation to the diet.
• Ultrasound Measurement:
  • Contractions were recorded via transcutaneous ultrasound at three anatomic sites: sternal flexure of the large colon, left ventral colon, and cecum.
  • Two ultrasonographers independently recorded the number of contractions during four consecutive 1-minute periods.
  • Recordings were taken twice daily: 2 hours after the morning feeding and 2 hours after the evening feeding.
  • A contraction was defined as any movement of the large intestinal wall exceeding 2 cm.
• Data Analysis: The Wilcoxon signed-rank and Kruskal-Wallis statistical tests were employed, with Bonferroni correction to control for multiple comparisons.

Key Findings

• Time of Day Effect: No significant difference was found in the frequency of large colon contractions based on whether measurements were taken after the morning or evening feeding.
• Sternal Flexure: Horses on the complete pelleted diet exhibited a significantly higher frequency of contractions at the sternal flexure of the large colon compared to those on the hay-based diet plus supplement.
• Left Ventral Colon and Cecum: No significant differences in contraction frequency were observed at these sites between the two diets or across the different times of measurement.

Interpretation and Implications

• The findings indicate that diet composition can selectively influence motility at certain areas of the large colon in healthy horses.
• Increased contractions at the sternal flexure with the pelleted diet might reflect diet-specific effects on intestinal motility patterns.
• Since motility is crucial for normal digestive function, understanding how diet alters intestinal contractions can help veterinarians better assess gastrointestinal health.
• The study suggests that dietary factors should be considered when evaluating equine gut motility, especially in clinical assessments or treatment planning.

Conclusion

• This research underscores the importance of diet in modulating large intestinal motility in horses.
• Use of transcutaneous ultrasound is demonstrated as a useful, non-invasive tool to quantify gut motility at specific anatomical sites.
• Veterinarians should take dietary influences into account to accurately interpret intestinal motility and maintain gastrointestinal wellness in horses.