The effect of milk urea level on fertility parameters in Holstein–Friesian dairy cows

Abstract

The objective of this study was to reveal the effect of milk urea levels on the fertility of dairy cows, taking into account their age, herd production level, number of cows, season of first insemination, which were analyzed using data from the SYMLEK national system. The study included data on milk urea levels in 88,745 test-day yields of 55,685 Holstein-Friesian cows, which were milked up to 30 days before first insemination, during the period preceding 180 days of first and second lactation. The GLM procedure of the SAS package was used in the statistical calculations. Considering the observed significant relationships and tendencies, a milk urea level higher than 300 mg/L was found to negatively affect reproductive efficiency in dairy cows, although the effects of the urea level could be masked by the more profound impact of environmental factors. Regardless of the factors, an increased milk urea level was paralleled by decreased cow fertility, with statistically significant differences occurring only for the interactions with herd production level and with herd size. The unfavorable effect of the increase in the level of urea in milk (from ≤150 to >300 mg/L) on cow fertility was particularly evident in the highest producing herds (>9000 kg milk).

Genetic analysis of milk urea concentration and its genetic relationship with selected traits of interest in dairy cows

“…In addition, to reduce potential unfavorable correlated responses, correlations of MU and traits included in the breeding goal have to be considered. Previous research showed that MU (or MUN) is correlated with yield traits (e.g., milk, protein, and fat yields; Yin et al, 2012;Beatson et al, 2019;Ariyarathne et al, 2021), type traits (Satoła et al, 2017b), BW (Hojman et al, 2005), SCC (Bobbo et al, 2019), and reproductive performance (Siatka et al, 2020;Kananub et al, 2020). However, results were not all indicating similar direction and strength of correlations.…”

“…The slightly positive genetic relationship found between MU and FF may be due to the slightly negative correlation between MU and MY and the relatively strong expectation that there is a negative correlation between FF and MY. Siatka et al (2020) reported that MU had a significant negative effect on the fertility of high-yielding dairy cattle. Moreover, the approximate genetic correlation found between MU and FF was lower at the end of the lactation (325 DIM).…”

“…The MU varies between individuals and is affected by many factors. Literature reported among others, the factors feed compositions (Correa-Luna et al, 2019), milking time (Bendelja et al, 2011), age at calving (Wood et al, 2003), stage of lactation and season of milking (Fatehi et al, 2012;Yin et al, 2012), herd and parity (Čobanović et al, 2017;Siatka et al, 2020), and genetics (Bendelja et al, 2011;Mucha and Strandberg, 2011;Rzewuska and Strabel, 2013).…”

Hepatic urea, creatinine and uric acid metabolism in dairy cows with divergent milk urea concentrations

“…Nitrogen emissions from livestock can have harmful effects on biodiversity, soil, water and air quality, as they account for 23% of global nitrous oxide and 60% of global ammonia (NH 3 ) emissions 4 . Besides, an increase in MUC from 150 to 300 mg/L reduces fertility, and levels above 300 mg/L are associated with infertility of cows 5,6 . Therefore, minimizing MUC without compromising the nutritional requirements of the animals may reduce environmental burden and increase fertility.It has been shown that MUC is a moderately heritable trait 7,8 and proposed that selection of cows for lower MUC concentration would reduce urinary urea and N emissions and thus the environmental footprint 1 .…”

Hepatic urea, creatinine and uric acid metabolism in dairy cows with divergent milk urea concentrations

“…Nitrogen emissions from livestock can have harmful effects on biodiversity, soil, water and air quality, as they account for 23% of global nitrous oxide and 60% of global ammonia (NH 3 ) emissions 3 . Besides, increased MUC is directly associated with infertility of cows 4,5 . Therefore, minimizing MUC without compromising the nutritional requirements of the animals may reduce environmental burden and increase fertility.…”