Effect of sampling intervals and digesta markers on abomasal flow determinations

Area of Science:

• Animal Nutrition
• Digestive Physiology
• Ruminant Metabolism

Background:

• Accurate measurement of nutrient flow in ruminants is crucial for understanding digestive processes and optimizing feed formulations.
• External and internal digesta markers are commonly used to track digesta passage and quantify nutrient utilization.
• Selecting appropriate markers and sampling strategies is essential for reliable data in animal nutrition research.

Purpose of the Study:

• To evaluate the efficacy of different digesta markers and sampling schedules for measuring non-ammonia nitrogen flow in abomasally-cannulated steers.
• To compare the suitability of polyethylene glycol (PEG), chromic oxide (Cr2O3), indigestible neutral detergent fiber (INDF), and indigestible acid detergent fiber (IADF) as digesta markers.
• To determine the optimal sampling interval for accurate digesta flow measurements.

Main Methods:

• Utilized abomasally-cannulated steers fed a consistent hourly diet of ground corn cobs, cane molasses, and soybean meal.
• Investigated four sampling schedules (24 hr, 48 hr, 48 hr sampled twice, 72 hr) and three digesta markers (PEG, Cr2O3, INDF, IADF).
• Assessed non-ammonia nitrogen flow as the primary criterion for comparing marker performance and sampling intervals.

Main Results:

• Sampling interval did not significantly affect abomasal digesta flow measurements.
• Extending sampling intervals beyond 24 hours or collecting multiple samples per day offered no discernible advantage.
• Indigestible acid detergent fiber (IADF) and chromic oxide (Cr2O3) demonstrated suitability as markers for the particulate fraction, with IADF meeting ideal marker criteria.

Conclusions:

• Indigestible acid detergent fiber (IADF) is a highly suitable internal marker for the particulate digesta fraction in ruminant studies.
• A 24-hour sampling interval appears sufficient for measuring non-ammonia nitrogen flow, and longer intervals or multiple samples per day are not beneficial.
• The findings support the use of IADF and Cr2O3 for accurate digesta marker studies in cattle nutrition.