Milk shipped from your dairy farm is weighed, sampled and analyzed. The weight and analysis are used to determine the economic value of each load of milk shipped. The price your farm receives per hundredweight of milk is based on weight, fat, protein, somatic cell count and adjustments.
Supplemental bulk tank milk analysis is not used in pricing but can provide value to milk urea nitrogen and milk fat fractions. Butterfat is analyzed into three fractions: denovo, nixed and preformed fat. Milk urea nitrogen and the three milk fat fractions are useful in evaluating your herd’s performance. This article will provide information on how to use milk urea nitrogen and milk fat fractions to improve your herd milk production and price.
Milk urea nitrogen
Milk urea nitrogen is analyzed on bulk tank milk and the values are reported in your milk plant report for each load. If your dairy plant does not provide these values, then request your milk fieldman to provide the information. Milk urea nitrogen, MUN, is urea that is transferred into the cow’s milk from the cow’s blood. When a cow digests feed, even if the feed does not contain urea, a portion of the diet protein along with muscle protein will break down to ammonia. Ammonia is toxic in the body so it is converted to urea in the liver and excreted from the cow as either milk urea nitrogen or urinary nitrogen. This is a normal healthy process that occurs in mammals, even humans.
MUN bulk tank values can provide valuable information to improve performance and farm profit. A MUN value too low or too high indicates the milking cows are consuming an imbalanced diet or being fed improperly. Normal bulk tank MUN is 8 to 12 MUN. Values below 8 or above 12 indicate feeding or ration imbalances. A range of issues can lower or elevate MUN some of which are imbalance of ration protein or starch, improperly processed corn, poor feed mixing or delivery, forage changes and cow feed sorting. Breed differences occur with Jersey milk being higher in MUN.
Consistency of MUN in the bulk tank milk is a valuable indicator of feeding and nutrition. MUN bulk tank values that vary by 2 MUN units within a week indicate a feeding or ration imbalance. A qualified nutritionist can provide insight into how to refine MUN bulk tank values and maintain consistency. MUN values above 16 can result in reproductive failure in dairy cows. TMR herds will have MUN higher due to late lactation cows consuming higher than required protein. Grouping cows by similar stage of lactation and production can improve MUN balance.
Milk fat
Bulk tank milk sample analysis also includes the milk fat fractions. Like MUN these milk fat fractions provide insight into cow performance.
A brief explanation of how butterfat is produced inside the cow is helpful in interpreting the three milk fat fractions. Milk fat is produced from two main sources. Dietary fiber digested in the first of the cow’s four stomachs produces a vinegar-smelling short two-carbon fat called acetate. The second source of butterfat is dietary fat from oils in silage, hay, grains, soybeans and added dietary fat like palm fat, protected fats or calcium salts like Megalac. The vegetable fats and some dietary fats are modified in the rumen, emulsified with bile in the upper small intestine and absorbed into the bloodstream in the lower small intestine. Additionally, body fat that is released from body fat stores contributes to long fat.
The long fats from diet and body join with short acetate fats in the cow’s udder. Each micro-sized milk secretory cell in the udder assembles the long and short fats in a specific combination, like a unique lock and key, to make milk fat. If the ratio of long or short fats is incorrect, milk fat will decrease for the herd.
Milk-producing cells in the udder manufacture milk with the proper ratio of butterfat, protein, lactose, minerals and vitamins.
A good dairy cow trivia question to ask your Christmas dinner guests. How many milk-producing cells exist in the udder of a 1,400-pound dairy cow that is producing 10 gallons of milk per day? The answer is 2.5 trillion cells that collectively weigh 50 pounds. Think of it as 1,350 pounds of cow weight wrapped around 50 pounds of udder to give 10 gallons of milk per day.
Bulk tank milk fat fractions
The milk fat fractions from bulk tank milk analysis provide valuable information to your nutritionist on proper diet formulation. Denovo bulk tank fat values denote short fats and indicate rumen fiber digestion. Preformed bulk tank fat values denote long fats and give an indication of dietary and body fat usage. The mixed milk fat fraction is a blend of the short and long fats. Recommended levels of each milk fat fraction are listed in Table 1. When values are below or above the goal review your ration formulation and feeding management with a nutritionist.
Farm economics
The single highest expense on the dairy farm is lactating feed. As a farmer, you get paid on the total pounds of milk components sold and not on the percentage of milk fat or milk protein percentage. Milk fat percentage has increased in recent years to 4% for Holstein herds and 5.5% for Jersey herds. The goal is to produce pounds of milk fat and milk protein and not maximize fat and protein percentage.
Pounds of milk fat shipped per cow per day provide the majority of farm income for your dairy in the current market. Milk fat pounds plus milk protein pounds along with milk component efficiency are highly related to dairy farm income. Top herds are achieving 7 pounds or greater of components per cow per day with some herds achieving over 8 pounds. For example, a Holstein herd with 100 pounds of milk per cow at 4% fat and 3% protein nets 7 pounds of components.
A calculation of milk component efficiency can help link production with feed expense and farm profit. Milk component efficiency is calculated as pounds of components divided by dry matter intake. A goal for component efficiency is 10.5% with top herds at 11.5% or greater. For example, a Holstein herd producing 7 pounds of components and consuming 66 pounds of ration dry matter intake will have a component efficiency of 10.6%.
Summary
From a dairy farmer’s perspective, evaluate your bulk tank milk MUN, fat fraction values and dry matter intake. Evaluate this data with your nutritionist, veterinarian and farm management team to create opportunities to improve your herd’s income and profitability. Achieve high components and efficient feed intake to keep your herd on a profitable track.
