Factors Associated with Milk Urea Concentrations in Ontario Dairy Cows

Department of Animal and Poultry Science, University of Guelph, XIA, Ontario, Canada
Journal of Dairy Science (Impact Factor: 2.57). 02/2001; 84(1):107-14. DOI: 10.3168/jds.S0022-0302(01)74458-X
Source: PubMed


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.

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    • "Milk minerals are negatively correlated with protein, SnF and minerals in first lactation where as moderate to strong relation was observed in second lactation with those parameters. Milk constituents didn't show any difference between local and crossbred cows.Some studies reported that MUN concentration were lower at first lactation than in older cows (Godden et al. 2000;Oltner et al. 1985), others have found no such relationship (Canfield et al. 1990). Several studies reported that urea levels vary considerably by stage of lactation (Bruckental et al. 1989;Carlsson et al. 1995).Carlsson et al. (1995)reported that MUN concentrations were lowest immediately after calving, increased to reach a maximum between 3 and 6 month of lactation, and then slowly declined in later lactation. "
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    ABSTRACT: This study was aimed to evaluate milk urea nitrogen (MUN) of cows considering variations in dietary nutrition, genetic quality and lactation yield which will be helpful to develop practical feeding guidelines for dairy cows based on MUN. A total of forty dairy cows consisting 20 native and 20 crossbred milking cows were selected in Sonaimuri, Noakhali in winter season to know the daily feed availability to cows. Feed, milk and blood samples were collected and analyzed. The dry matter intake of the local and crossbred cows were 2.58 and 2.74 (g/100 kg live weight respectively) and they did not show statistical variation (p<0.05). Metabolizable energy (ME) and protein intake showed significantly higher values in crossbred (85 MJ/day and 815 g/day) compared to local (40 MJ/day and 395 g/day) cows in winter season (p>0.05). Live weight, body condition score and milk yield and MUN varied significantly between genotypes although blood urea nitrogen (BUN) value did not differ significantly. Strong correlation between lactose and protein percentage was observed in both the lactations in local cows. Milk minerals are negatively correlated with protein, SnF and minerals in first lactation whereas moderate to strong relation was observed in second lactation with those parameters. Milk constituents didn’t show any difference between local & crossbred cows. Strong correlation between milk protein and lactose with SnF were observed in both local and crossbred cows in first lactation stage. BUN value showed a moderate correlation between milk yields of local cows. The results revealed that genotype and lactation have no effect on BUN although MUN value showed significant difference between local and crossbred cows.Bangladesh J. of Livestock Res. 19(1-2): 74-84, Jan-Dec 2012
    Full-text · Article · Jan 2016
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    • "The transformed-SCC was not different with respect to MUN (P>0.05). This is contrary to reports by Godden et al. (2001), Hojman et al. (2004), and Rajala-Schultz and Saville (2003), who found a highly significant negative relationship between MUN and SCC. On the contrary, Pedraza et al. (2006) reported that MUN concentration increased significantly with increasing SCC values. "
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    ABSTRACT: The objective of this study was to evaluate lactose and milk urea nitrogen (MUN) in milk from Holstein cows and their relationship with days in milk (DIM), milk yield, milk fat, milk protein, and somatic cell count (SCC). A total of 1,034 records corresponding to morning and afternoon milkings of 148 Holstein cows were used. Records were taken from 16 herds located in the Northern and Eastern dairy regions of Antioquia (Colombia). The curves were fitted using a generalized additive mixed model with smoothed estimates to find the best smoothing intensity factors involved in MUN and lactose concentration. Regarding MUN, the contemporary group effect was highly significant, but the parity effect was not significant. The DIM, lactose and milk fat smoothed covariates were highly significant, while milk yield and fat and SCC showed no statistical difference. Regarding lactose content, the contemporary group effect was highly significant, while the parity effect was not significant. Days in milk, MUN, milk fat, milk protein, and afternoon-milking SCC smoothed covariates were highly significant, while milk yield and morning-milking SCC were not significant. Lactose and milk urea nitrogen concentrations are affected by various factors throughout lactation, mainly by days in milk.
    Full-text · Article · Sep 2014 · Revista Brasileira de Zootecnia
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    • "In accordance with other studies ( Godden et al . , 2001 ; Arunvipas et al . , 2003 ; Nyman et al . , 2009 ) , we found a negative association with milk urea concen - tration and SCC . To our knowledge , the association between bovine milk urea concentration and LDH , NAGase , or AP activities in milk is scarcely described ."
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    ABSTRACT: The objective of this study was to investigate if and how cow factors and intramammary infection (IMI) are associated with 4 different udder-health indicators in dairy cows as a first step in investigating whether the diagnostic performance of these indicators can be improved. The investigated indicators were somatic cell count (SCC), lactate dehydrogenase (LDH), N-acetyl-β-d-glucosaminidase (NAGase), and alkaline phosphatase (AP) measured in milk. In this cross-sectional study, approximately 1,000 cows from 25 dairy herds were sampled for bacteriology (quarter milk samples) during 3 consecutive days: the day before test milking, at the day of test milking, and at the day after test milking. The whole-udder test milking sample was analyzed for milk composition, SCC, LDH, NAGase, and AP. Cow data (parity, breed, milk yield, percentage of milk fat and protein, milk urea concentration, and days in milk from the sampled test milking) were collected from the Swedish milk-recording scheme. Of the sampled cows 485 were considered IMI negative and were used in multivariable mixed-effect linear regression models to investigate associations between cow factors and the udder-health indicators. A second modeling including all cows, both IMI negative and IMI positive (256 cows), was also performed. The results showed that all udder-health indicators were affected by cow factors but that different cow factors were associated with different indicators. Intramammary-infection status was significantly associated with all udder-health indicators except AP. Parity and milk urea concentration were the only cow factors associated with all indicators in all models. The significant cow factors explained 23% of the variation in SCC and >30% of the variation in LDH, NAGase, and AP in IMI-negative cows, showing that LDH, NAGase, and AP are more affected than SCC by cow factors. The IMI status explained 23% of the variation in SCC in the model with all cows but only 7% of the variation in LDH and 2% of the variation in NAGase, indicating that SCC has the best potential as a diagnostic tool in finding cows with IMI. However, further studies are needed to investigate whether the diagnostic properties of these udder-health indicators will improve with adjustment according to their associations with different cow factors when used as a diagnostic tool for finding cows with IMI.
    Full-text · Article · Jul 2014 · Journal of Dairy Science
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