Milk urea nitrogen concentration is higher in Brown Swiss than in Holstein dairy cows despite identical feeding.

Kessler, Evelyne C; Bruckmaier, Rupert M; Gross, Josef J. (2020). Milk urea nitrogen concentration is higher in Brown Swiss than in Holstein dairy cows despite identical feeding. Journal of animal physiology and animal nutrition, 104(6), pp. 1671-1677. Blackwell Science 10.1111/jpn.13408

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Milk urea nitrogen (MUN) content is closely related to blood urea nitrogen (BUN) concentration and reflects the balance of dietary crude protein and energy supply for ruminal microbial metabolism. The present study investigated whether the higher MUN content in Brown Swiss (BSW) compared with Holstein (HOL) cows is related to milk production and feeding conditions. Therefore, we evaluated test-day records of three consecutive official milk recordings from 86 BSW and 200 HOL cows kept on the same farm under identical feeding and management conditions. In addition, the relationships between BUN and MUN assessed either by an enzymatic method or by mid-infrared spectroscopy were analysed. For the second objective, milk and blood samples (1,112 samples each) were collected in parallel from day 5 until day 150 of lactation from 141 dairy cows housed at different farms. Concentrations of MUN determined either enzymatically (MUNENZ ) or by Fourier transform infrared spectroscopy (FTIR; MUNIR ) were regressed on the BUN concentrations of the concomitantly obtained blood samples. Both MUNIR and MUNENZ were well correlated with BUN (r = .93 and .89 respectively). Concentration of MUN was higher in BSW compared with HOL independently of lactational stage or parity number (p < .0001). Protein and fat content were higher in BSW than in HOL (p < .05). Primiparous cows had lower milk yield and ECM (p < .001 for BSW, p < .0001 for HOL) than multiparous in both breeds. Multiparous BSW had a similar milk production than primiparous HOL (p = .13). In conclusion, BSW cows have higher MUN than HOL when kept under identical feeding and management conditions. The higher MUN in BSW compared with HOL cows is not related to milk production and therefore rather genetically determined.

Item Type:

Journal Article (Original Article)

Division/Institute:

05 Veterinary Medicine > Department of Clinical Research and Veterinary Public Health (DCR-VPH) > Veterinary Physiology

UniBE Contributor:

Gross, Josef Johann

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 590 Animals (Zoology)

ISSN:

0931-2439

Publisher:

Blackwell Science

Language:

English

Submitter:

Josef Johann Gross

Date Deposited:

19 Nov 2020 14:34

Last Modified:

19 Nov 2020 14:34

Publisher DOI:

10.1111/jpn.13408

PubMed ID:

32588951

Uncontrolled Keywords:

Brown Swiss Holstein dairy cow milk urea nitrogen

BORIS DOI:

10.7892/boris.148238

URI:

https://boris.unibe.ch/id/eprint/148238

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