Nutrient sources for offspring formation: diet–mother and mother–offspring isotope discrimination in domesticated gallinaceous birds

Abstract

ABSTRACT Stable isotope techniques can be used to assess nutrient acquisition and allocation strategies used to produce offspring. Before stable isotope techniques can be employed, researchers need reliable isotope discrimination values. In this context, isotope discrimination compares the difference in the isotope ratio between the maternal–offspring tissue that occurs during nutrient transfer prior to egg laying. Currently, isotope discrimination values are unknown between the maternal blood constituents – that reflect different temporal scales of integration – and downy feathers of their offspring. In this study, we experimentally derive isotope discrimination relationships between maternal diet–blood constituents for egg laying, and between maternal blood constituents–down feathers of offspring in an experiment with 3 types of domesticated gallinaceous birds raised on known diets. Our experiment is the first to report isotope discrimination values for maternal blood constituents–down of offspring in avian taxa and provides a new sampling technique that is less invasive than previously available as collecting down does not require sampling viable eggs or individuals. Future researchers can use these results to assist in identifying nutrient sources used by adult birds to produce young.