Environmental factors influencing milk urea nitrogen in South African Holstein cattle

Abstract

By knowing the milk urea nitrogen (MUN) content of dairy cows, the efficiency of dietary nitrogen utilization can be improved. The main objectives of this study were to identify and quantify environmental factors affecting MUN in South African Holstein cows. This will enable better interpretation of MUN results by accounting for such factors. A total of 82 900 test-day records of 9 901 Holstein cows from 40 herds participating in the South African National Milk Recording and Improvement Scheme (NMRIS) during the period 2007 to 2010 were used. An analysis of variance was performed to determine environmental factors significantly affecting MUN. Significant factors were herd-test-day, year of calving, parity, number of times milked per day and lactation stage. Herd-test-day had the largest effect, accounting for 48.3% of the total variation. Trends in least squares (LS) means for MUN over lactation stages were similar for all parities; however, means were slightly lower in parity 3 than the first two parities. The LS mean for 2008 was the lowest (13.9 mg/dL) in comparison to other years. Cows milked twice daily had a higher MUN LS mean (15.5 mg/dL) in comparison to those milked three times per day (13.4 mg/dL). Results of this study provided the basis for proper use and better interpretation of MUN data.

Winter and spring variation in daily milk yield and mineral composition of Jersey, Friesian cows and their crosses under a pasture-based dairy system

“…These results are comparable with 30.5 kg/day observed by Kgole et al (2012) in South African Holstein cattle and a 305 days average of 16.28 kg/day in Jersey cows by Meeske et al (2006). Mostert et al (2003) and Palladino et al (2010) reported a similar trend in production with higher milk yield in Holstein-Friesian cows than in Jersey cows.…”

<b>Gir and Guzerat cow milk production and composition according to lactation stage, somatic cell count, physiological state and body condition

“…Physicochemical composition of cow milk is of great importance when it comes to nutritional value and its industrial processing ability, and varies according to several factors, among which are: breed, diet, udder health, lactation stage and physiological factors (pregnant or non-pregnant) (Aikman, Reynolds, & Beever, 2008;Dufour, Fréchette, Barkema, Mussell, & Scholl, 2011). Proteins, lipids and lactose are the constituents that vary the most during lactation (Kgole, Visser, & Banga, 2012;Sharma, Singh, & Bhadwal, 2011) generally showing higher values when lactation reaches advanced stages (Aganga, Amarteifio, & Nkile, 2002).…”

Genetic and environmental determinants of the urea level in cow's milk

“…Season and milking systems influenced MU (P <0.001). Kgole et al (2012) noted that MUN was significantly affected by herd test day, year of calving, parity, number of milkings per day, and the lactation phase.…”

“…However, it should be noted that, for accurate interpretation of the urea content, not only the feed factor but also other factors should be taken into consideration. These factors include breed (Rodriguez et al, 1997), parity (Broderick and Clayton, 1997;Godden et al, 2001;Sawa et al, 2011), body weight (Kohn et al, 2002), milk yield (Godden et al, 2001), fat and protein content, days in milk (DIM), milking frequency (Godden et al, 2001;Kgole et al, 2012), and month of the year (Arunvipas et al, 2003;Biswajit et al, 2011;Borkowska et al, 2012;Frand et al, 2003;Hojman et al, 2004;Kgole et al, 2012;Oudah, 2009;Rafieei, 2011;Rzewuska and Strabel, 2013b). In Polish breeding programmes, urea content in cow milk has been monitored since 2000.…”