The effect of non-nutritional factors on milk urea nitrogen levels in dairy cows in Prince Edward Island, Canada

Sources of variation in milk urea nitrogen in Paraná dairy cows

“…Milk urea nitrogen (MUN) has been used as an indicator to monitor the protein-energy balance of lactating cows (Jonker et al, 1999;Godden et al, 2001b), once it shows a high correlation with plasma and blood urea nitrogen (Roseler et al, 1993;Lucci et al, 2006). The samples to determine MUN were collected using a noninvasive and direct method through milk samples collected during milking, thus representing a simple, fast and cheap indicator to investigate the nutritional condition of lactating cows (Roseler et al, 1993;Butler et al, 1995).…”

“…Based on studies with dairy herds enrolled in a monthly milk recording program (Godden et al, 2001a,b;Arunvipas et al, 2003;Johnson & Young, 2003;Rajala-Schultz & Saville, 2003;Wattiaux et al, 2005), it was found that several non-nutritional factors are associated with MUN concentrations.…”

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

“…Studies reporting lower MUN values in the first lactation suggested that primiparas were still growing and therefore might have used amino acids more effectively (Arunvipas et al, 2003;Canfield et al, 1990;Carlsson et al, 1995;Ferguson et al, 1997;Ng-Kwai-Hang et al, 1985;Oltner et al, 1985). According to Doska et al (2012), primiparas showed higher MUN values compared to multiparas, which may be explained by the lower milk production of younger cows.…”

“…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.…”

“…Hojman et al (2004) reported that production and environmental factors account for 37 % of the variation in MU. Arunvipas et al (2003) stated that factors such as breed, parity, days in milk, milk production, milk quality, and milk components were responsible for 13.3 % of the variation in MUN concentration. RajalaSchultz et al (2001) indicate that increased MUN levels appeared to be negatively related to dairy cow fertility.…”