The article focuses on the impact of different dairy management types on quality characteristics of organic and conventional milk. The study was conducted during 9 months (spring-autumn), raw milk samples were collected from organic and conventional dairy farms from two Ukrainian regions. The milk samples were analyzed for dry matter, total protein and non-protein nitrogen, ammonia content and values of stable isotopes 13С/12С were measured in fat and milk protein fractions. The values of dry matter, total protein, true protein and non-protein nitrogen content do not represent a statistically significant effect of farming type. The values of ammonia content, ammonia/non-protein nitrogen and ammonia/total protein ratios were statistically significant and reflected the impact of farming type which is, probably, linked with different protein content in cows’ diet. Conversion of some parameters on the dry matter allows more precise differentiation among types of milk, including statistically significant differences (e.g. total protein and ammonia content). The values of δ13C in fat fraction (-26.00‰) and protein fraction (-22.89‰) of organic milk were statistically significant differed in comparison with conventional milk (-23.14 ‰ and -19.15‰ respectively), due to the high amount of maize in the diet on conventional farm. The values of Δδ13C also were statistically significant: 3.99‰ in conventional milk and 3.11‰ in organic. It was established that conventional milk has a greater range of the different parameter seasonal variations than organic milk.

The influence of farming type (conventional or organic) and production system (low-and high-input) on various quality characteristics of milk have been in the focus of studies over the last decade. The aim of this work was to evaluate the impact of different dairy management and production systems on carbon stable isotopes ratio (δ 13 C) and milk urea content. The samples of raw milk were collected each two weeks at certified organic high-input and low-input farms, conventional high-input and low-input farms in late indoor period and outdoor period. Data analysis showed clear difference between milk from organic high-and low-input farms with non-overlapping range between -22.90 ‰ and -24.70‰ for δ