Effects of herd, season and days in milk on milk urea nitrogen of crossbred dairy cows in Sylhet

Md Abdul Baset,Md Abdullah Al Mahmud,Md Tariqul Islam,Nusrat Zahan Shoshe,Shiekh Ma Matin

doi:10.3329/ralf.v2i2.25012

Md Abdul Baset, Md Abdullah Al Mahmud + Show 3 more

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https://doi.org/10.3329/ralf.v2i2.25012

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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

Highlights

Milk urea nitrogen (MUN), a fraction of milk protein that is derived from blood urea nitrogen (BUN), may be one of the useful tools (Zhai et al, 2006; Dhali et al, 2005 and Peterson et al, 2004) that may help monitoring of any change required in the feeding and management of a herd
Test day observations were combined into a data set that included herd code, date of test, milk yield, milk fat content, milk protein content, milk urea (MU) concentration, breeding date and days in milk (DIM)
It is possible that the high milk urea nitrogen (MUN) may be caused by high concentrate ration

Summary

Introduction

Milk urea nitrogen (MUN), a fraction of milk protein that is derived from blood urea nitrogen (BUN), may be one of the useful tools (Zhai et al, 2006; Dhali et al, 2005 and Peterson et al, 2004) that may help monitoring of any change required in the feeding and management of a herd. 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). If MUN values are high, a herd may experience wasting of feed protein along with excess excretion of nitrogen into the environment causing pollution. If MUN values are too low, the rumen microbial protein yield may be reduced thereby limiting milk production and milk protein yield (Brodrick and Clayton, 1997)

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