Milk urea concentration as a tool for optimising crude protein content in dairy goat diets: a path to sustainable milk production

Milk urea concentration (MU) has been extensively studied and is often used to evaluate energy and protein balance in dairy cattle diets, but not to this extent in dairy goat diets. The aim of this study was to determine the relationship between MU concentration and crude protein content (CP) in the diet of Alpine goats in order to reduce excessive nitrogen excretion from the organism. For this purpose, 72 goats were randomly divided into three equal groups (24 animals) and fed a concentrate mix containing 14%, 16%, and 18% CP, respectively. The chemical composition of milk samples was determined and the ratio of milk fat to protein was calculated. Statistical analysis of the data was performed using the MIXED procedure (SAS V8 software package). Increasing CP from 14% to 16% in the diet increased daily milk yield by 0.4 kg (p<0.001), and MU concentration from 35.01 to 41.24 mg/100 mL (p<0.001). Based on the calculated inflection point of daily milk yield and protein content in milk, the range of MU concentration from 40.00 to 45.00 mg/100 mL can be considered optimal and is a good indicator of a balanced diet for goats.