Factors Associated with Milk Urea Concentrations in Ontario Dairy Cows

Abstract

All DHI test-day data, including milk urea concentrations measured by infrared test method, were collected from 60 commercial Ontario Holstein dairy herds for a 13-mo period between December 1, 1995, and December 31, 1996. The objectives of this study were to describe the relationships between milk urea concentrations and seasonal factors, sampling factors, cow factors, and test-day production of milk, milk fat, protein, and SCC. Milk urea was associated with month and season; concentrations were the highest from July to September. Milk urea was generally lower in first-lactation cows. Milk urea was lowest during the first 60 d of lactation, higher between 60 and 150 d in milk, and lower after approximately 150 d in milk. In herds on an alternating a.m./p.m. test schedule, milk urea was generally lower in a.m. than p.m. tests. There was a positive nonlinear association between milk urea and milk yield, fat-corrected milk, and energy-corrected milk. There was a negative nonlinear association between milk urea and both milk fat and total protein percentages. While there was a negative nonlinear association between cow-level milk urea and linear score, the study found no association between herd average milk urea and herd average linear score. The associations described in this study using Dairy Herd Improvement test-day samples from commercial dairy herds and using an infrared test to measure milk urea are generally consistent with results from studies that used individual animals housed under research conditions and chemical methods to measure milk urea. Because milk urea varies by season, month, parity group, stage of lactation, and sample type, studies should control for these variables. Because of the apparent effect of a.m. and p.m. sampling on urea concentration, producers on an alternating a.m./p.m. test schedule should test routinely to establish a herd pattern for urea and submit the same sampling time consistently or both.

Blood biochemical profile of Sudanese crossbred repeat breeder cows

“…We also found that the plasma urea nitrogen of the RB cows was significantly higher (P < 0.05) than that of the NC cows (Table 1). This result comes in a line with previous studies (Godden et al, 2001;Kurykin et al, 2011). The high plasma level of urea nitrogen may be the cause of production of abnormal oocytes in RB cows (Kurykin et al, 2011).…”

Modeling milk urea of Walloon dairy cows in management perspectives

“…Moreover, MU concentrations are related to individual production traits, such as test-day production of milk, fat, or protein. Several studies have also associated MU with environmental effects, such as season, month of calving, parity group, or stage of lactation (Broderick and Clayton, 1997;Godden et al, 2001;Rajala-Schultz and Saville, 2003).…”

Monitoring the nutritional and reproductive state of dairy cows through the presence of urea in milk

“…An elevated concentration of urea in milk also means a nonbalanced diet (Broderick and Clayton, 1997). Besides, the more urea in milk, the lower would be the concentration of true proteins, mainly casein (Westwood et al, 1998;Canfield et al, 1990;Godden et al, 2001a).…”

“…This indicate the need to differentiate multiparous and multiparous in the assessments. Differences in dry matter intake, adaptation of ruminal microorganisms and the ruminal capacity of absorption may contribute to modify the MUN concentration at different stages of lactation (Godden et al, 2001a;Rigolon et al, 2009). However, when controlling nutrition, Eicher et al (1999) observed no association between the number of parity, stage of lactation and MUN concentration, thus suggesting that non-nutritional factors have little effect on the relationship.…”