A preliminary study on Milk Urea Nitrogen values of the Ambewela farm

Abstract

Feeding management is a key factor in profit maximizing of a dairy farm. Milk Urea Nitrogen (MUN) is a tool that measures the efficiency of protein and carbohydrate feeding to milking cows (Jonker et al., 1999). Implementing routine use of MUN on dairy farms could reduce nutrient loading to natural environments and improve farm profitability (Jonker et al., 2002). According to Kohn (2007) dairy herds should have MUN concentrations between 8 to 12 mg dL . However, the MUN values could be affected by many factors such as environment Feeding management is a key factor in profit maximizing of a dairy farm. Milk Urea Nitrogen (MUN) is a tool that measures the efficiency of protein and carbohydrate feeding to milking cows (Jonker et al., 1999). Implementing routine use of MUN on dairy farms could reduce nutrient loading to natural environments and improve farm profitability (Jonker et al., 2002). According to Kohn (2007) dairy herds should have MUN concentrations between 8 to 12 mg dL . However, the MUN values could be affected by many factors such as environment MUN values to evaluate the dairy herds in the Sri Lanka would be inappropriate, since there were no studies carried out in to determine the baselines of MUN values in Sri Lanka. Therefore, this study has been carried out as a preliminary study, to study about the prevailing MUN values of one of the commercial dairy farm in Sri Lanka. Methodology

The study was conducted at Ambewela farm and Veterinary Research Institute, Sri Lanka. Four groups of the milking herd in the Ambewela farm (treatments) which have been made based on the production levels of the cows were used to collect milk samples. Samples from each group were taken once in fortnight during three months’ experimental period. During each sample collection, 15 cows were selected randomly from each group and 50 mL of milk from each cow was obtained after complete milking. Milk from five cows belonging to each group was pooled. Hence, each treatment consisted with three replicates. Milk fat was analyzed using the Gerber method. Solids-non-fat (SNF), protein, salts and lactose contents were measured using a portable ultrasonic milk analyzer (Lactoscan MCC, Milkotronic Ltd., Bulgaria). Lacto meter was used to measure the milk specific gravity. The urea content in milk was estimated according to the method described by Malik and Sirohi (1998) and the optical density of the sample was measured at 450 nm using the spectrophotometer (Cary 50 Conc - 10069600, Agilent Technologies, Australia). In the statistical analysis, according to the normality of the sample data test by Anderson-Darling test, the relationships were evaluated using multiple regression analysis or Spearman Rank Correlation Coefficient. STATA S/E

11.2 and Minitab 17 software were used in statistical analysis of the data. The MUN levels were interpreted based on the current recommended levels of Kohn (2007).