Skip to main content
NCBI home page
Acta Veterinaria Scandinavica logoLink to Acta Veterinaria Scandinavica
. 1994 Mar 1;35(1):66–77. doi: 10.1186/BF03548356

The Diurnal Variation of Urea in Cow’s Milk and how Milk Fat Content, Storage and Preservation Affects Analysis by a Flow Injection Technique

J Carlsson 1,✉, J Bergström 1
PMCID: PMC8101404

Abstract

Six Swedish Red and White dairy cows, producing 20-39 kg of 4% fat-corrected milk were given a ration balanced in energy and protein. They had access to feed from 05.15 to 09.00 and from 13.00 to 16.30 and were milked at 06.15 and 15.30. The milk was analysed for urea with a FIA technique.

There was a significant diurnal variation in milk urea. The highest values were found 3–5 h after the beginning of the morning feeding and the lowest values (down to 60% of the max. values) during late night. Within 1 h after the start of the morning feeding the urea values had increased significantly, but they had decreased within the same time after the start of the afternoon feeding. Since there was a pronounced diurnal variation in the milk fat content, the urea concentration was also recalculated to concentration in the water phase of the milk. It was higher in that phase, but the pattern of the diurnal variation was not changed significantly. However, analyses on milk with a very high fat content may give misleading results.

There were no important differences in the milk urea concentration of different udder quarters. When calculated as concentration in the water phase of the milk, no differences in urea concentration were found between the beginning and the end of milking. The analytical method had a good precision (coefficient of variation max. 3%). The milk urea concentration was not changed significantly after storage during 10 days at 4°C when no preservative was added; but after 17 days the milk had turned sour and the urea value had increased. When a preservative (bronopole) was added the urea concentration remained unchanged during 17 days. Deepfreezing did not influence the urea concentration.

Keywords: milk urea, milk profile test, FIA-technique, milk components, dairy cows

Full Text

The Full Text of this article is available as a PDF (1.7 MB).

Acknowledgments

The investigation was supported by the Swedish Farmers’ Foundation for Research.

References

  1. Andersson G, Andersson L, Carlström G. Determination of milk urea by Flow Injection Analysis. J. Vet. Med. A. 1986;33:53–58. doi: 10.1111/j.1439-0442.1986.tb00505.x. [DOI] [PubMed] [Google Scholar]
  2. Beutlhauser B. Milk urea concentration in milk, and body fluids in high yielding dairy cows. Germany: University of Munich; 1982. Harnstoffkonzentration in Milch und Körperflüssigkeiten bei Hochleistungskühen. [Google Scholar]
  3. Blauwiekel R, Kincaid RL. Effect of crude protein and solubility on performance and blood constituents of dairy cows. J. Dairy Sci. 1986;69:2091–2098. doi: 10.3168/jds.S0022-0302(86)80641-5. [DOI] [PubMed] [Google Scholar]
  4. Carlsson J, Pehrson B: The influence of the dietary balance between energy and protein on milk urea concentration. Experimental trials assessed by 2 different protein evaluation systems. Submitted for publication in Acta vet. scand. [DOI] [PMC free article] [PubMed]
  5. Carroll DJ, Barton BA, Andersson GW, Smith RD. Influence of protein intake and feeding strategy on reproductive performance of dairy cows. J. Dairy Sci. 1988;71:3470–3481. doi: 10.3168/jds.S0022-0302(88)79953-1. [DOI] [PubMed] [Google Scholar]
  6. Folman Y, Neumark H, Kaim M, Kaufmann W. Performance, rumen and blood metabolites in high-yielding cows fed varying protein percents and protected soyabean. J. Dairy Sci. 1981;64:759–768. doi: 10.3168/jds.S0022-0302(81)82645-8. [DOI] [Google Scholar]
  7. Gustafsson AH, Carlsson J. Effects of silage quality, protein evaluation systems and milk urea content on milk yield and reproduction in dairy cows. Livest. Prod. Sci. 1993;37:91–105. doi: 10.1016/0301-6226(93)90066-Q. [DOI] [Google Scholar]
  8. Gustafsson AH, Emanuelson M, Oltner R, Wiktorsson H. Department of Animal Nutrition and Management. Swedish University of Agricultural Sciences. 1987. Mjölkens ureahalt, dess variation och päverkan av besättning, mjölkavkastning, lakta- tionsstadium, säsong och utfodring. (Milk urea level, its variations and how it is affected by herd, milk yield, stage of lactation, season and feeding - a field study) [Google Scholar]
  9. Gustafsson AH, Palmquist DL. Diurnal variation of rumen ammonia and serum and milk urea in dairy cows at high and low yield. J. Dairy Sci. 1993;76:475–484. doi: 10.3168/jds.S0022-0302(93)77368-3. [DOI] [PubMed] [Google Scholar]
  10. Haag T. The value of milk urea determinations in dairy cows with special reference to methodological studies. Giessen, Germany: Justus-Liebig-University; 1988. Zum Aussagewert der Harnstoffbestimmung in der Milch vom Rind unter besonderer Berücksichtigung methodischer Untersuchungen. [Google Scholar]
  11. Hammond AC. Effect of dietary protein level, ruminal protein solubility and time after feeding on plasma urea nitrogen and the relationship of plasma urea nitrogen to other ruminal and plasma parameters. J. Anim. Sci. 1983;57:435. [Google Scholar]
  12. Hoffmann M, Steinhöfel O. Möglichkeiten und Grenzen zur Einschätzung der Energie- und Proteinversorgung durch Kontrolle des Milchharnstoffgehaltes. (Possibilities and restrictions for evaluation of the dietary energy and protein balance by analysis of the milk urea concentration). Mh. Vet. Med. 1990;45:223–227. [Google Scholar]
  13. Kaufmann W. Variation in der Zusammensetzung des Rohstoffes Milch unter besonderer Berücksichtigung des Harnstoffgehaltes. (Variations in the composition of milk with special reference to the urea concentration). Milchwissenschaft. 1982;37:6–9. [Google Scholar]
  14. Miettinen PVA, Juvonen RO. Diurnal variations of serum and milk urea levels in dairy cows. Acta agric. scand. 1990;40:289–296. doi: 10.1080/00015129009438563. [DOI] [Google Scholar]
  15. Oltner R, Wiktorsson H. Urea concentrations in milk and blood as influenced by feeding varying amounts of protein and energy to dairy cows. Livest. Prod. Sci. 1983;10:457–467. doi: 10.1016/0301-6226(83)90073-8. [DOI] [Google Scholar]
  16. Refsdal AO. Urea in bulk milk as compared to the herd mean of urea in blood. Acta vet. scand. 1983;24:518–520. doi: 10.1186/BF03546724. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Ropstad E, Vik-Mo L, Refsdal AO. Levels of milk urea, plasma constituents and rumen liquid ammonia in relation to the feeding of dairy cows during early lactation. Acta vet. scand. 1989;30:199–208. doi: 10.1186/BF03548056. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. SAS Institute Inc. SAS/STAT Guide for personal computers. 1987. [Google Scholar]
  19. Wolfschoon-Pombo AF. Investigations on the amount and composition of NPN in milk. Germany: University of Munich; 1981. Untersuchungen über die Menge und Zusammensetzung der sogenannten NPN in Milch. [Google Scholar]

Articles from Acta Veterinaria Scandinavica are provided here courtesy of BMC

RESOURCES