Lactose and milk urea nitrogen: fluctuations during lactation in Holstein cows

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.

Macar Siyah Alaca İneklerinde Süt Verimi, Bileşimi ve Somatik Hücre Sayısını Etkileyen Genetik Olmayan Faktörler

“…In contrast, lactose ratio decreased in the latest SL group. This finding was inline with the results of the some researchers [21] , who found that the lactose curve showed a progressive decrease as stage of lactation advanced. A general concept that milk production reaches to peak level in lactating cows at the beginning phase of the lactation.…”

“…In a study [24] , it was determined the lowest protein percentage in the summer and the highest percentage in the winter. However, while lactose in milk was higher in winter and spring CS groups, this result was found as harmonic with the indication of some researchers [21] , who explained this case by inadequate forage supplementation of diet in these months.…”

Treatment and post-treatment effects of dietary supplementation with safflower oil and linseed oil on milk components and blood metabolites of Canadian Holstein cows

“…Milk lactose determines milk osmolality and its synthesis determines the rate of water secretion in milk (Miglior et al 2006). It should be noted that the water content of milk largely determines milk fat and protein concentrations (Henao-Velásquez et al 2014).…”

An effect of mammary gland infection caused by Streptococcus uberis on composition and physicochemical changes of cows’ milk

“…Other authors did not observe an effect of somatic cell count, and thus mammary gland status, on milk urea level (Henao-Velásquez et al 2014). In turn, Nielsen et al (2005) noted an increased urea production in mammary gland in inflammation states, which is an evidence of contradictory literature data.…”