Document Type : Research Paper
Professor, Department of Animal Science, University of Zanjan, Iran
Former M.Sc. Student, Department of Animal Science, University of Zanjan, Iran
Ph.D. Student of Ruminant Nutrition, Department of Animal Science, University of Zanjan, Iran
This study was performed to evaluate the effects of crud protein (CP) level on dry matter intake in prepartum period, productive performance and health of fresh cows. Twenty multiparous Holstein cows were assigned randomly to one of two dietary treatments. Dietary treatments were treatment 1, 13% CP of DM (control), and treatment 2, 16% CP of DM. Diets were similar in lactation net energy and rumen degradable protein and CP levels increased with RUP supplements. All cows had 50 days of far-off, and 10 days of close-up periods. Prepartum dry matter intake in treatment 2 was significantly greater than in control treatment (P>0.05). Milk production, fat corrected milk, and milk fat and lactose yields in treatment 2 were significantly higher than in control treatment (P>0.05). Changes in body condition score (BCS) were not significantly affected by treatments. Although blood urea nitrogen (BUN) was significantly higher in treatment 2, but β- hydroxybutyrate (BHB) and phosphorus concentrations were significantly decreased in treatment 2 compared to control treatment. The incidence of metabolic disorders, such as hypophosphatemia, and hypomagnesemia were significantly greater in treatment 2 compared to control treatment. Overall, results of this study showed that increasing crude protein through RUP sources in a shortened close-up period increased prepartum DMI, milk production after calving, and reduced incidence of ketosis in Holstein fresh cows.