Influence of feed and water on the stable isotopic composition of dairy milk

Abstract:
Traceability of dairy products is an important issue for the dairy industry. Empirical studies have demonstrated the utility of stable isotope measurements on milk for verification of origin. However, various drivers influence the isotopic composition of a food stuff, such as rainfall levels or food supplements. Relationships between the isotopic composition (δ2H, δ18O, δ13C and δ15N) of milk fatty acids, the water component of the milk, and feed and farm water from 18 New Zealand dairy farms were studied. Significant relationships between the isotopic composition of milk and both farm water and feed fatty acids were observed. Measurement of both diet and drinking water from each dairy farm enabled the underlying environmental correlations to milk fatty acids to be explored by analysis of their respective δ2H values. Development of this technology may provide a diagnostic tool for determining type and the origin of dietary feed utilised in milk production.