Feed sorting remains one of the most common challenges encountered on dairy farms feeding Total Mixed Rations (TMRs). While emphasis is placed on forage quality, chop length and providing a balanced diet, sometimes the diet the cows actually consume can be very different.
Sorting behaviour is a natural response by dairy cows, particularly when presented with dry rations containing a wide range of particle sizes, for example, concentrates, chopped straw, root crops and silages. Although individual sorting behaviour may appear insignificant, the cumulative effect across a herd can substantially alter nutrient intake and rumen function.
The consequences can be a very different diet being consumed by dominant cows compared with timid heifers or cows lower in the pecking order. If diets are not eaten evenly, the risk of subacute ruminal acidosis (SARA) increases. Fluctuating rumen pH can limit fibre digestion and negatively influence milk fat production. In addition to this, the milk yields produced from the diet can alter drastically if diet intakes are variable.
Adding water to the diet can increase intakes and reduce sorting. However, bear in mind that, with current temperatures, diets can warm up and cause feed spoilage. Mixing the water will mean that cows cannot sort the diet as easily due to the wet nature of the ration and ensure a more balanced intake. Ideally, you should be aiming for a diet dry matter at 38-42% to prevent sorting, increasing intakes and overall palatability.
Adding water to a TMR diet
The method of water addition is equally important. Water should be introduced gradually during the mixing process rather than applied immediately before feed-out. Even distribution throughout the ration allows forage particles to absorb moisture and improves adhesion between ingredients without creating excessively wet pockets within the mix. Fundamentally, it needs to be easy to do so that it can get carried out efficiently. A large pump provides a quick and easy addition to the mix. A few different options to include water in the ration would be:
- A fixed water pipe on the wagon with a volume washer attachment. This way the feeder wagon can have water filled while simultaneously distributing water evenly across the mix.
- A large volume output pipe dropping down, mimicking a molasses outlet. If the outlet pipe can have multiple entry points into the wagon, it will then improve the consistency of the mix that is then fed out to the cows.
Monitoring refusals provides valuable feedback on ration performance. Refusals containing disproportionately high levels of long forage indicate ongoing sorting and should prompt investigation of ration moisture and mixing efficiency. Similarly, observing cow feeding behaviour immediately after fresh feed delivery can provide useful insight into the extent of ingredient selection occurring within the herd.
Water is arguably the least costly ingredient available on the farm, yet when used strategically it can significantly improve ration consistency, reduce sorting and support more stable rumen function.
The importance of water to the animal
Water availability is just as important outside of the TMR. High yielding cows can drink up to 200 litres a day. Cows need to have 70cm of water trough space per cow. This equates to a 100-cow herd having a minimum of 7m of total water trough space. Trough space should allow 10% of the herd to drink at any one time. Water pressure needs to be rapid refilling, so water is always in front of the cows. Cows can drink 14 litres a minute, so 10 cows drinking simultaneously can consume 140 litres every minute.
In this heat, many herds would have seen the effects and pressure points of water supply during the hot weather and adding water to a TMR only increases this demand. Careful planning of water tank storage and supply is becoming increasingly important with the weather patterns the summer months seem to be giving up.
Speak to your Harpers Feeds Specialist to find out more.
