Kevin Scallon, Director of Technical Services

Feeding a total mixed ration (TMR) to dairy cows allows the cow to consume the appropriate amounts of all ration ingredients consistently and uniformly throughout the day. Care is taken to select appropriate ration ingredients. The ration is formulated and fine-tuned. Feed ingredients are carefully weighed and blended in the TMR mixer. The ration looks fine on paper. All nutrient parameters are where they should be yet the cows are not performing as they should. Dry matter intakes might be inconsistent. Manure consistency within groups vary. Butterfat test may be dropping. What’s happening?

The cows may be exhibiting signs of clinical or subclinical acidosis caused by slug feeding of concentrates. How can that be after all the trouble we went through to mix everything together?

Many cows are very skilled at sorting or taking apart the TMR we so carefully crafted. Recent research at the University of Wisconsin – Madison demonstrates this skill very well. In feeding TMR to individual cows and measuring what they actually consumed over time using a forage particle separator, researchers found some animals consumed all TMR fractions (concentrates and forages of all lengths) equally and consistently over the course of a day. However, there were other cows that effectively sorted out virtually 100% of the long forage particles.

While it may be difficult to change the individual tastes and preferences of cows within the herd or group, there are things that can be done to make it more difficult, or less likely, for the cows to sort. Read on to learn about some areas we should be focusing on to deal with sorting.

Particle size Long hay is easy for cows to sort out. Ideally, if long hay is added to the TMR, it should be processed or chopped to less than the width of a cow’s muzzle.

Forage Quality Make every attempt to put up high quality, palatable forage. Attention paid to details such as timing of cutting and chopping, moisture, particle length, inoculation, packing, covering and feed out can pay dividends at feed out.

TMR Moisture TMR moisture levels can have an effect on TMR intake. Higher moisture levels (> 50% but not more than 53-55%) make the TMR more palatable and make it more difficult for the cows to sort out the finer concentrate particles. Many dairyman add water to the TMR with a garden hose to increase moisture. While this is effective in increasing TMR moisture, many find it to be too time consuming. Water can be added more quickly to the mixer by using a tank with enough capacity to hold the amount of water necessary for the batch size, a float valve to regulate fill level on the tank and a high capacity sump or centrifugal pump. Gravity also works well if there is an elevated location for the tank. Keep in mind, there can be some drawbacks to adding water. Freezing temperatures in winter can be a problem. In the summer, some have also observed an increase in TMR heating when water is added.

Molasses Adding molasses to the TMR does not typically increase the moisture content but it does add some “stick ’em”. When added at about 3 pounds per head per day there is usually enough “stick ’em” to effectively reduce sorting as measured with a particle separator. Molasses can also enhance the appeal of all TMR components by adding a palatable coating. Winter feeding of molasses can be a problem (molasses in January) but can be overcome by using a blend or “winterized” formulation. Also, propionic acid can be added to the molasses in the summer as a very effective and inexpensive means of reducing TMR heating.

References: “Feed sorting leads to acidosis, other problems” Mary Beth de Ondarza; Hoard’s Dairyman. “It’s Acidosis, But How Did It Happen?”, Mike Hutjens; Agri-View, January 6, 2000 “Update on fiber feeding for lactating cows: Focus on sorting”, Lou Armentano, Dairy Science Department, UW-Madison.