Urea Concentration in the Milk of Alpine Goats

Summary Nutrition is considered the primary paragenetic factor influencing the milk urea (MU) concentration in ruminants. In addition to diet, various other factors (including season, milk yield, stage of lactation, etc.) have also been shown to affect the urea concentration in ruminant milk. While the physiological concentration of MU has been well-defined for cow's milk, with an optimal range of 15 to 30 mg/dl, such parameters have yet to be established for goat's milk. The objective of this study was to determine the urea concentration in the milk of Alpine goats and to assess its correlation with the daily milk yield and the contents of fat, protein, lactose, and solids-not-fat (SNF). A total of 3,009 samples of Alpine goat milk, collected from two farms in 2021, were analyzed. The average MU concentration was 37.3 ± 8.9 mg/dl, with a range from 13.8 to 110.7 mg/dl. The average daily milk yield was 1.15 ± 0.49 kg, whereas the average milk fat and protein contents were 3.28 ± 0.97% and 3.35 ± 0.50%, respectively. The study found a positive and statistically significant correlation between the MU concentration and the contents of milk fat, protein, and SNF. Conversely, an increase in the MU concentration was negatively correlated with the daily milk yield. Monitoring the MU concentration in dairy goat herds enables the optimization of feed rations, particularly their protein and energy contents, thus improving nitrogen utilization in milk production.