Milk Urea Nitrogen as a Tool for Optimum Feeding of Crossbred Dairy Cows

Milk urea nitrogen (MUN) measurement is a convenient and non-invasive method to assess the protein and energy nutrition of dairy cattle. High MUN levels are reported in repeat breeding animals. Thirty six crossbred cows maintained under two different situations i.e. 18 each from a dairy farm or village (field) conditions to study the effect of production, managemental and nutritional variables on base line MUN. The milk samples were collected for 8 weeks alternatively during morning or evening milking from 6 animals each in early (0–45), mid (46–150) and late (>150 days in milk) stages of lactation. MUN was estimated for 7 days in 6 animals with history of repeat breeding in each situation. The situation wise feedstuff, nutrient profile, animal performance data along with environmental profile were fed into CNCPS version 5.0 to evaluate the diets, animal performance, formulate optimized diets for repeat breeding animals and to study the effect of feeding such diets on MUN levels and post AI conception. The average base line MUN (mg/dl) vs. the MUN in repeat breeding cows was 10.90 vs.10.93 (farm cows) and 11.20 vs. 11.63(field cows). However, in four out of the six repeat breeding cows screened for MUN in the farm or field situation, the MUN (mg/dl) was higher, 12.31 (farm cows) and 12.36 (field cows) than the mean baseline MUN indicating that mere comparison of mean values may be misleading.. The MUN (mg/dl) decreased (P<0.05) in repeat breeding farm (7.53) and field (8.12) cows by feeding optimized (using CNCPS version 5.0) rations. The base line MUN levels were influenced by production, nutritional and managemental variables. It was concluded that MUN can be employed as a potential tool to evaluate protein nutrition of dairy cattle and CNCPS version may be used to formulate optimized situation specific diets for scientific feeding of dairy cattle.