Responses in Urea and True Protein of Milk to Different Protein Feeding Schemes for Dairy Cows

Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Kennett Square 19348, USA.
Journal of Dairy Science (Impact Factor: 2.57). 12/1995; 78(11):2424-34. DOI: 10.3168/jds.S0022-0302(95)76871-0
Source: PubMed


Four multiparous Holstein cows were used in a 4 x 4 Latin square to investigate the effects of protein concentration, degradability, and quality on plasma urea concentration and milk N constituents. Diets varied in the amount and proportion of RDP and RUP relative to NRC requirements: diet 1, excessive RDP, deficient RUP; diets 2 and 3, balanced for RDP and RUP; and diet 4, excessive RDP, balanced for RUP. Diet 3 was formulated for optimal AA balance as predicted by the Cornell Net Carbohydrate and Protein System. Diets contained 34% corn silage, 19% alfalfa haylage, and 49% concentrate (DM basis). Concentrates varied in amounts of urea and soybean, corn gluten, and fish and blood meals. Concentrations of urea N and NPN in milk varied among diets: diet 1, 19 and 34 mg/dl; diet 2, 16 and 31 mg/dl; diet 3, 15 and 30 mg/dl; and diet 4, 23 and 39 mg/dl, respectively. Increases in NPN concentration were attributed to increases in the urea fraction of NPN. Intake of RUP and AA balance influenced milk true protein content; diet 1, 2.89%; diet 2, 2.90%; diet 3, 3.01%; and diet 4, 2.95%. the proportions of true protein and urea in milk are influenced by CP concentration, protein type, and protein quality.

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    • "Urea concentration in milk and plasma are closely related (Gustafsson and Plamquist, 1993). Several investigators have suggested the possibility of using either of them as a supplementary indicator of nitrogen utilization and feeding adequacy in dairy cows (Roseler et al. 1993;Baker et al. 1995;Hof et al. 1997;Shepers and Meijer, 1998;Jonker et al. 2002;Dhali et al. 2005). Milk urea nitrogen (MUN) provides an accurate reflection of how much nitrogen is absorbed by the cow, but not used for growth or milk protein synthesis. "
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    ABSTRACT: This study was aimed to evaluate milk urea nitrogen (MUN) of cows considering variations in dietary nutrition, genetic quality and lactation yield which will be helpful to develop practical feeding guidelines for dairy cows based on MUN. A total of forty dairy cows consisting 20 native and 20 crossbred milking cows were selected in Sonaimuri, Noakhali in winter season to know the daily feed availability to cows. Feed, milk and blood samples were collected and analyzed. The dry matter intake of the local and crossbred cows were 2.58 and 2.74 (g/100 kg live weight respectively) and they did not show statistical variation (p<0.05). Metabolizable energy (ME) and protein intake showed significantly higher values in crossbred (85 MJ/day and 815 g/day) compared to local (40 MJ/day and 395 g/day) cows in winter season (p>0.05). Live weight, body condition score and milk yield and MUN varied significantly between genotypes although blood urea nitrogen (BUN) value did not differ significantly. Strong correlation between lactose and protein percentage was observed in both the lactations in local cows. Milk minerals are negatively correlated with protein, SnF and minerals in first lactation whereas moderate to strong relation was observed in second lactation with those parameters. Milk constituents didn’t show any difference between local & crossbred cows. Strong correlation between milk protein and lactose with SnF were observed in both local and crossbred cows in first lactation stage. BUN value showed a moderate correlation between milk yields of local cows. The results revealed that genotype and lactation have no effect on BUN although MUN value showed significant difference between local and crossbred cows.Bangladesh J. of Livestock Res. 19(1-2): 74-84, Jan-Dec 2012
    Full-text · Article · Jan 2016
    • "of the milk non-protein nitrogen. Milk urea nitrogen (MUN) concentration for individual cow ranges from 8 to 25 mg/dL while optimum concentration for a herd ranges from 12 to 17 mg/dL (Hwang et al. 2000; Baker et al. 1995; Roseler et al. 1993). Average MUN values may range from 10 to 14 mg/dL (Moore and Verga, 1986; Carlsson and Pehrson, 1994). "

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    • "The MUN has been used as a noninvasive measurement to monitor the animal's protein status and the efficiency of N (nitrogen) utilization (Brodrick and Clayton, 1997; Jonker et al., 1998; Eicher et al., 1999). Normal value of BUN in cows is 15 mg/dl (Roseler et al., 1993) and MUN concentration for individual cow ranges from 8 to 25 mg/dl while optimum concentration for a herd ranges from 12 to 17 mg/dl (Baker et al., 1995; Hwang et al., 2000). Imaizumi et al. (2010) and Moore and Verga (1986) reported average MUN values may range from 10 to 14 mg/dl. "
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    ABSTRACT: The study included 724 crossbred cows (Local × Holstein Friesian) from 9 dairy farms of Sylhet district from July 2013 to June 2014 to determine the effect of herd, season, and days in milk in milk urea nitrogen and the effect of milk production and composition on milk urea nitrogen. According to the season, milk samples were divided into two groups: wet season (June - October) and dry season (November - February). Days in milk (DIM) were grouped into two lactation stages: Lactation 1 (˂100 days in milk) and Lactation 2 (˃100 days in milk). Milk urea nitrogen was grouped into five categories by increments of 5 mg/dl, started with those less than 10 mg/dl and finishing with concentration greater than 25 mg/dl. The daily milk yield was 6.78 kg ranged from 2.00 to 18.00 kg. The mean of milk urea nitrogen (MUN) concentration was 14.58 mg/dl. Mean values for milk fat and protein contents were 3.74 % and 3.72 %. Among the 9 herds, the highest content of milk urea (MU) was 16.37 mg/dl which was found in herd 2 and the second highest estimation of MU content were in herd 1, 3, 6 and 9 (15.58, 15.51, 15.12 and 14.45 mg/dl, respectively). In the district of Sylhet, the lowest MU content was estimated in herd 4, 5, 7 and 8 (13.59, 13.48, 13.16 and 13.60 mg/dl, respectively). Difference of MUN concentration was not significant between the dry and wet season. The MUN concentrations were 14.82 mg/dl and 14.90 mg/dl in dry and wet season respectively. The concentration of MUN in Lactation 1 was 13.61 mg/dl and in Lactation 2 was 16.26 mg/dl. Milk fat (%) were 3.56, 3.77, 3.64, 4.15 and 3.66 when MUN concentration were ≤10.00, 10.01- 15.00, 15.01-20.00, 20.01-25.00 and ≥24.01 mg/dl respectively. Daily milk yield did not increase with the increase of MUN concentration. Milk yield were 6.37, 7.21, 6.23, 7.31 and 7.00 Kg/d while MUN concentration were ≤10.00, 10.01-15.00, 15.01-20.00, 20.01-25.00 and ≥25.01 mg/dl. It may be concluded that herd category and lactation stage influence the milk urea nitrogen concentration of crossbred dairy cows in the Sylhet district.Res. Agric., Livest. Fish.2(2): 287-292, August 2015
    Full-text · Article · Sep 2015
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