Feasibility studies in rats fed heavy metals as multiple nutrient markers

Area of Science:

• Animal Nutrition
• Digestive Physiology
• Trace Element Metabolism

Background:

• Accurate assessment of nutrient digestibility in animal studies is crucial.
• Nonabsorbed inert markers are valuable tools for fecal recovery and passage time determination.
• Evaluating novel markers is essential for improving experimental methodologies.

Purpose of the Study:

• To assess the feasibility of using cerium, terbium, ytterbium, lutetium, and iridium nitrates as nonabsorbed multiple markers in rats.
• To evaluate marker recovery, fecal passage time, and diurnal variation.
• To determine the suitability of these markers for indirect apparent digestibility studies.

Main Methods:

• Oral administration of metal nitrates to rats.
• Collection and analysis of fecal samples to determine marker recovery and concentration.
• Comparison of direct and indirect methods for nutrient apparent digestibility.
• Investigation of diurnal variation in fecal marker concentrations.

Main Results:

• Fecal recovery of a single oral dose was achieved within 72 hours.
• Steady-state fecal marker concentrations were established within 48-96 hours when mixed in the diet.
• Lutetium exhibited negligible diurnal variation in fecal concentration when incorporated into the diet.
• Cerium showed considerable diurnal variation when administered as a single dose prior to feeding.
• Good agreement was observed between direct and indirect multiple marker methods for nutrient digestibility.

Conclusions:

• Lutetium nitrate is a promising nonabsorbed marker for digestibility studies due to its stable fecal concentration.
• Cerium nitrate is not recommended as a multiple marker when using neutron activation analysis due to significant diurnal variation.
• Metal nitrates can be effectively used as nonabsorbed markers for recovery, passage, and digestibility studies in rats.