Ytterbium acetate as a particulate-phase digesta-flow marker

Area of Science:

• Animal Nutrition
• Digestive Physiology
• Ruminant Metabolism

Background:

• Accurate measurement of digesta flow is crucial for understanding nutrient utilization in ruminants.
• Particulate-phase markers are needed to complement liquid-phase markers for a comprehensive digesta flow analysis.
• Chromium ethylenediaminetetraacetic acid (CrEDTA) is a commonly used liquid-phase marker, but its accuracy can be limited.

Purpose of the Study:

• To evaluate ytterbium acetate (Yb acetate) as a particulate-phase digesta flow marker.
• To assess the indigestible acid-detergent-fibre fraction (IADF) as a digesta flow marker.
• To investigate the efficacy of a dual-phase marker system (CrEDTA and Yb acetate) for estimating digesta flow in sheep.

Main Methods:

• Six mature wether sheep were fed dried grass, with continuous infusion of CrEDTA and Yb acetate into the rumen.
• Digesta and fecal samples were analyzed for marker concentrations using atomic absorption spectrometry.
• Dry matter (DM) excretion and flow at the duodenum and ileum were estimated using marker recovery.

Main Results:

• Yb acetate and IADF provided reliable estimates of fecal DM excretion, comparable to total collection.
• CrEDTA underestimated fecal DM excretion.
• The dual-phase marker system (CrEDTA + Yb acetate) provided more reliable duodenal flow estimates than individual markers, especially with unrepresentative samples.
• Yb acetate was primarily associated with particulate digesta and its concentration increased with decreasing particle size.

Conclusions:

• Yb acetate is a suitable particulate-phase marker for digesta flow studies in sheep.
• The combination of CrEDTA and Yb acetate offers a more robust dual-phase marker system for accurate digesta flow estimation.
• This dual-phase approach enhances the reliability of nutrient flow measurements, particularly at the duodenum.