economic value and produced milk quality in holstein lactating cows in organic system

in the past decade, a global demand for products from organic agriculture has increased rapidly. milk quality is of major interest for all parties. therefore, the objective of this study was to compare cow performance and product quality in conventional and organic system. twenty holstein dairy cows were allotted to one of 2 diet groups, which including: a conventional diet (con), and an organic system with high forage (ohf). multiparous cows (3rd and 4th parity) were randomly assigned to the treatments. range forages were used as part of diets and cows were offered concentrate and silage two times a day. dry matter intake (dmi) and milk yield were measured across 200 d. furthermore, somatic cell count, feed cost and feed efficiency were determined at 20 day intervals. the milk yield was different for cows that treated with the ohf (22.5 kg/d) and con (28.9 kg/d) systems, respectively. body weights were not affected by treatments; however, differences in body condition scores (p<0.05) were observed. although energy corrected milk, milk urea nitrogen, cortisol and β-hydroxybutyrate acid were higher in cows fed con system; milk fat, phytanic acid, hippuric acid and profit to cost ratio were higher (p<0.05) in cows fed organic system. additionally, lower feed efficiency, feed cost and blood urea nitrogen were observed in cows fed organic diets (p<0.05).