Effects of Using Monensin and Different Levels of Crude Protein on Milk Production, Blood Metabolites and Digestion of Dairy Cows (Report‪)‬

INTRODUCTION At the beginning of lactation, dairy cows have to cope with the high energy and protein demands for milk synthesis at a time when nutrient intake is low. Mobilizing energy and protein from body tissue stores and repartition of nutrients away from extra-mammary tissues are the primary alternatives to supply sufficient nutrients for milk production during the first weeks of lactation. Excessive body reserves, especially fat, can subject cows to a series of metabolic disorders and consequent production losses (Fourichon et al., 1999). Maltz and Silanikove (1996) determined that high-yielding dairy cows had a negative nitrogen balance of 52 and 40 g/d at 2 and 7 wk postpartum, respectively. Komaragiri and Erdman (1997) assumed that cows have a greater capacity to mobilize body fat than protein and that in high-yielding dairy cows both energy and protein are limiting. It is believed that a reduction of this negative balance will contribute to increased production and health and more efficient use of dietary protein in early lactation by dairy cows.