Genetic and environmental determinants of the urea level in cow's milk

Abstract

Abstract. This study was conducted on a sample of 2237 Polish Holstein-Friesian cows. The aim was to estimate the effect of selected environmental factors on the level of urea in cow's milk and on its genetic parameters, i.e. the heritability coefficients, and genetic correlation with other selected traits of milk production. The present study has revealed the existence of a highly significant influence of herd, year of calving, parity, lactation phase, and milk performance level on the urea content in cow's milk. A high urea level in milk was detected in samples collected from older animals, both during the winter season and the middle phase of lactation (101-200 days).The heritability estimates were generally at a low level, particularly in terms of milk yield (0.183) and urea content (0.152-0.159), which may indicate the dominant role of the environment in shaping them. Relatively low values of genetic correlation (−0.097-0.140) between the urea content and other traits suggest that improvement of milk yield and its composition modify the urea level in milk only to a small degree.

Composite genotypes of progestagen-associated endometrial protein gene and their association with composition and quality of dairy cattle milk

“…On the other hand, low UC may cause health and fertility problems [ 20 ]. Literature suggests that the optimal UC in cow’s milk is between 150 and 300 mg/L [ 20 , 21 ]. In the present study UC did not exceed 300 mg/L (on the average UC was 245.01 to 270.1 mg/L) ( Table 5 ).…”

Comparison of yield, composition and quality of milk of Polish Holstein-Friesian cows in conventional and automatic milking systems

“…Berry et al (2013) Monitoring urea level in milk is important as it may enable farmers to indicate cases of health problems that may affect cow fertility. It has been stated that the optimal urea content in cow's milk is 150 -300 mg/l (Czajkowska et al, 2015;Rzewuska and Strabel, 2013). In the study of Czajkowska et al (2015), the content of urea in milk was within a normal range (206.4 mg/l).…”

“…It has been stated that the optimal urea content in cow's milk is 150 -300 mg/l (Czajkowska et al, 2015;Rzewuska and Strabel, 2013). In the study of Czajkowska et al (2015), the content of urea in milk was within a normal range (206.4 mg/l). Similarly, Rzewuska and Strabel (2013) reported that during the 1 st lactation the average urea content was 230.1 mg/l, and did not change significantly during the 2 nd lactation (230.3 mg/l).…”

The effect of milk urea level on fertility parameters in Holstein–Friesian dairy cows

“…From a zootechnical and economic point of view, recording the urea content of test-day milk is a quick, inexpensive, convenient, noninvasive, and above all useful method, as it informs the farmer about the efficiency of protein utilization and provides a basis for proper ration formulation (1,2,3). Based on several studies (1,4,5,6), and keeping nutritional considerations in mind, the optimum milk urea concentration for large breeds of dairy cows (e.g., Holstein-Friesian) was determined as 150-300 mg/L (2.5-5.0 mmol/L). However, some authors (2,7,8) indicate that urea levels around 200 mg/L or lower may be responsible for poor reproductive performance in dairy cows.…”