Effect of forage feeding level on body weight, body condition score, milk production, and milk urea nitrogen of holstein cows on an organic diet

In the past decade, a global demand for products from organic agriculture has increased rapidly. Milk quality is of major interest to all parties. Therefore, the objective of this study was to compare cow performance and product quality on conventional and organic diets. 72 Holstein dairy cows were allotted to one of four diets: a conventional diet (CON40), an organic diet with a low amount of forage (ORG40), an organic diet with a moderate amount of forage (ORG60) and an organic diet with a high amount of forage (ORG80). Multiparous cows (2^nd, 3^rd, and 4^th parity) were randomly assigned to the treatments. Range forages were used as part of the diets, and cows were individually offered feed three times a day with refus-als collected once a day. Daily dry matter intake (DMI) and milk yield (MY) were measured for 308 days. Somatic cell count (SCC), body weight (BW) and feed efficiency (FE) were determined at 28-day intervals. The DMI was different for cows that consumed the ORG80 (18.2 kg/d), ORG60 (19.1 kg/d), ORG40 (20.1 kg/d) and CON40 (20.5 kg/d) diets. BW was not affected by treatments, but differences in body condition score (BCS) (P<0.05) were observed. Although milk yield was higher in cows fed CON40, milk fat was higher (P<0.05) in cows fed organic diets. Lower FE, milk urea nitrogen (MUN) and blood urea nitrogen (BUN) were observed in cows fed organic diets (P<0.05).