Variations of Natural ¹⁵N Abundances in the Tissues and Digesta of Domestic Animals

Abstract

The natural abundance of ¹⁵N (expressed as δ¹⁵N per mil relative to air N₂) in the tissues and the change of ¹⁵N abundance during the digestion processess in cattle, pig, and goat were investigated.
The ¹⁵N abundances of cattle tissues differed by about 3.5‰ with high values in heart, urinary bladder and diaphragm. The ages of cattle did not affect on the ¹⁵N abundances of liver and kidney in cattle. The ¹⁵N abundances of urine were lower, and those of feces were a little higher than the values of diets in cattle and pigs. The δ¹⁵N values of milk and blood were higher than the value of diets. Two peaks of ¹⁵N abundances at forestomach and caecum were observed during the digestion processes of diet in goats.
The mechanisms of the variation of ¹⁵N abundances in animal bodies were briefly discussed.