13C analysis of cow tail hair and farm slurry can be used to implicitly distinguish between different dairy production systems

Abstract

Abstract Background Public interest in the way food is produced on the farm and processed along the food-production chain is increasing. The analysis of isotopic signatures (13C) in cow tail hair provides a method to reconstruct the dietary proportion of maize in cow diets. Based on this, we further investigated whether there is a relationship between isotopic signatures in cow tail hair or farm slurry and the proportion of maize of the total utilized agricultural area per farm [%]. We did an on-farm survey on 17 dairy farms in coastal Northwest Germany and collected cow tail hair from dairy cows and slurry samples on each farm. The farms differed in their feeding regime (C3 vs. C4 plants), their site conditions (sandy soil = ‘Geestland’; organic soil = ‘Peatland’; clayey soil = ‘Marshland’), and in the area cultivated with maize as a proportion of the total utilized agricultural area per farm. Results We found a positive relationship between δ13C values in both cow tail hair and slurry and the annual dietary proportion of maize (R2 = 0.67; and R2 = 0.63). Furthermore, we confirmed that there was a relationship between δ13C values in cow tail hair and area of maize as a proportion of the total utilized agricultural area per farm (R2 = 0.69). Conclusion Our findings suggest a general applicability of using isotopic signatures (13C) along a wide gradient of site conditions and productions systems in practice.