Abstract

Milk urea nitrogen (MUN) has been used to indicate the dietary protein/energy balance for the dairy cow, and may be negatively associated with the content of valuable milk components for the manufacture of dairy products. The objective of the study was to model the temporal pattern of the correlation between MUN and the percentages of fat (FP), protein (PP), lactose (LP) and total milk solids (MSP), and somatic cell score (SCS) (log2somatic cell count) of bulk milk samples from farms supplying milk for the manufacture of cheese and milk powder. Daily records of milk delivery dates, the composition of bulk milk samples for FP, PP, LP, MSP, SCS and MUN from 28 seasonal supply dairy farms were analysed. The results show there is a negative association between MUN and milk components. The concentration of MUN in milk of New Zealand cows is high compared with that of milk from cows fed a total-mixed-ration, due to the high crude protein content in the pasture fed to dairy cows in New Zealand.

JG, Garcia-Muniz, N Lopez-Villalobos, JL Burken, T Sandbrok, and CG Vazquez-Pelaez

Proceedings of the New Zealand Society of Animal Production, Volume 73, Hamilton, 108-113, 2013