Factors affecting the milk urea nitrogen concentration in Chinese Holstein cows

Abstract

In order to investigate the factors affecting milk urea nitrogen in Chinese Holstein cows, a large commercial dairy farm participated in a 30-month study. In this study, the mean milk urea nitrogen concentration was 11.75 mg/dl. The milk urea nitrogen reached its maximum value on day 90 of lactation for the first parity and the third or higher parities, but it peaked at the end of lactation for the second parity. The milk urea nitrogen of the first parity was lower than that of other parities. The milk urea nitrogen showed its minimum level in January, and reached its maximum in July. The milk urea nitrogen at the first month of lactation in cows calving in summer was higher than other seasons, while at the fourth month of lactation, the milk urea nitrogen of cows calving in autumn was significantly lower than in cows calving in other seasons. Positive correlations were observed between daily milk yield, net energy for lactation, crude protein and milk urea nitrogen for the first and third parities, but negative correlations were observed in the second parity. The milk urea nitrogen showed significantly positive correlations with fat content, total solid content and daily matter intake for all parities. A negative correlation was observed between milk urea nitrogen and protein content, with the exception of the second parity. For all data, as milk urea nitrogen concentration increased, milk protein content decreased. It has been recommended that milk urea nitrogen concentration should be evaluated in combination with parity, days in milk, season (or month), daily matter intake and dietary nutritional components, in order to improve the management and economic benefits of dairy farm.

Evaluation of the milk urea content in relation to milk production and composition in dairy cows

“…The evaluation of milk protein in relation to MU confirmed a negative regression dependency, which was the strongest in early lactation (r = -0.850; P < 0.001), decreasing in mid lactation (r = -0.819; P < 0.001) and late lactation (r = -0.679; P < 0.001). Our results are consistent with previous studies by Zhang et al (2018), who confirmed the negative dependency between milk protein and MU in dairy cows. Other studies examining this relationship did not find a significant correlation between these parameters (Kananub et al 2018).…”

Variability and correlation of milk urea content with parameters of cow productivity

“…The most significant exceedance of the norm for MU was observed at the second-third months of lactation (33.46-33.49 mg%). These results coincide with the data of other studies [1,3,12,13], but some authors did not find the connection between the concentration of urea and the stage of lactation, or they detected an increase in the level of urea from the first to the fifth-seventh months [14]. Lactation changes in the level of MU are inverse in relation to the variations in MF and MP, the content of which, starting from the second-third months of lactation, gradually increases to maximum in the last month of lactation.…”

Maternal Supplementary Tapioca Polysaccharide Iron Improves the Growth Performance of Piglets by Regulating the Active Components of Colostrum and Cord Blood

“…Furthermore, leukocytes and epithelial cells make up the majority of somatic cell types in milk and colostrum. According to Maurer et al [28], the somatic cell count (SCC) of milk is frequently used as a barometer for the well-being and quality of lactating animals, and the urea nitrogen concentration is a measure of urine nitrogen excretion that is connected to dietary crude protein (CP) intake and the ratio of degradable to undegradable protein [29].…”