Maximizing Dry Matter Intake When Using a TMR

 

 

Achieving optimum feed intake is important to maximizing milk production. A one-pound change in dry matter intake (DMI) usually results in a two to three-lb change in milk production. It is not uncommon to see a four-lb change in milk per cow from one day to the next as a result of changes in feed consumption. Fluctuations in feed intake are often caused by uncontrollable factors such as the weather; however, many fluctuations are the result of poor feeding management practices. In particular, those practices that cause an imbalanced pattern of carbohydrate (grain) consumption cause chaotic feed consumption patterns that often substantially reduce the total amount of DM the cow consumes over the course of one lactation.

Feeding Management and Acidosis
Invariably, when one observes wide fluctuations in feed intake, acidosis has occurred or will soon occur. This means that an unexpected increase in feed intake should also be viewed warily. Acidosis can lead to many secondary problems including bloat, low milk components (especially milk fat), reduced DM intake, displaced abomasum, reduced immunity, poor milk production, lameness, and others. Lameness alone can cost in excess of $100 per cow annually due to milk loss which can exceed 750 lb of milk per episode. Of course, there are many diseases associated with lameness. Often a dairy producer will blame a foot problem on disease when it is actually a direct or indirect result of acidosis. When poorly fed, the most carefully balanced ration can cause acidosis. One of the secrets to successful grain feeding is good bunk management.

Bunk-reading and Grain Feeding
Increasing grain intake too rapidly can cause acidosis. When DM intake is increasing early in lactation, producers need to ignore the desire to feed cows to appetite, regardless of when and how much their feed was last increased. Consider this scenario: Feed intake for a group of cows is on the increase. The amount fed is increased by three lb/cow (as-fed). If the ration contains at least 40% to 50% grain, the amount of grain fed is increased by 1.2 lb/cow. The following day, the producer observes a slick bunk and feeds the group an additional three lb/cow. The next day, feed is again increased another three lb/cow. The amount of grain in the ration has increased by 3.6 lb/cow in only three days. Initially, cows appear to hold the higher intake for one to three days after which time the producer begins to observe some loose stools and a slight decrease in intake. Many times feed intake drops very fast, below the original level. At this point, milk tank weights will reflect the variation in feed intake.

It is critical to keep a record (log) of the amount of feed delivered to each group. Unfortunately, very few dairy producers keep such records. This log should not only include the amount of feed delivered to the pen but also the estimated amount of feed weighed back. A feed log gives the producer a concise view of actual feed intake. Good records can indicate when cows in a particular pen are sick, when the ration is poorly balanced, when feed intake has been stepped up too fast, or when something is wrong with one of the ingredients. The latter is particularly true with a change in forage. Forage quality impacts consumption. By tracking feed intake, a producer can tell how the cows are performing even before these problems are reflected in milk tank weights.

 Published recommendations indicate a 3% to 5% daily feed refusal should be targeted. These recommendations probably reflect a fear of short-changing the cow in DM intake. Many producers ignore this recommendation and rely upon their experience to regulate feed intake. Total mixed ration feeding guidelines followed by many producers include:

  • If bunks are completely clean and dry or "dry slick," the cows have been out of feed too long. In such case, an increase in feed is indicated-four lb/cow of a wet silage ration or two lb/cow of a dry hay ration.

  • If the bunks are completely clean, but appear wet or "wet slick," the cows have just finished cleaning up the bunk, which is still "wet" with saliva.  No feed increase would be indicated at this time, but the bunk must be monitored very carefully for future changes.

  • If feed is left in the bunk, a reduction in the amount of feed offered is necessary. The producer must then estimate the amount of feed left and reduce it by a corresponding amount.

In short, the dairy producer should see the bottom of the bunk at least once a day, but cows should not be without feed for more than one or two hours each day. If the cows do go off feed, they will usually stabilize at some point below the original high figure. At that time, the producer can simply average the intake for the last three days and offer that amount of feed.

Feed refusal should never exceed 3% to 5%. When feed refusal exceeds this level the amount delivered must be reduced and the ration will probably need to be recalculated to deliver the correct balance of nutrients. Occasionally, cows will sort out long hay in a TMR. If this occurs, it may be necessary to grind (chop) hay a little shorter to encourage consumption.

Feed Delivery and Push-up
Fresh, palatable feed should be available to cows after they are milked. It is then that cows eat the most feed during the day. Cows will first drink, then begin eating. It is imperative that cows be provided clean water once they leave the milking parlor. Placement of a water tank in the alley which cows pass through when returning to the pen is desirable.

The more times a cow is fed, the more she consumes. Although feeding numerous times daily is good for intake, it is labor intensive. Therefore, delivering feed two to three times per day and then simply pushing the feed to the cows periodically can greatly encourage intake. Each time the feed is "pushed up" most of the cows come to the bunk to investigate and will then consume feed.

A good rule of thumb is that the number of feeding should equal the number of milkings; however, rations must then be pushed up to the cows as many times as is feasible. Increasing the number of times feed was pushed up resulted in a DMI increase of one to two lb/cow on some dairies.

The ration must be distributed uniformly in the bunk from end to end. Most cows are creatures of habit and will return to the same spot to feed. Failure to deliver feed to all of the "favorite spots" may reduce intake. This problem occurs more often when lockup stanchions are used.

Cows must be offered fresh feed in a clean bunk every day. Dirty, moldy, or stale feed or the presence of foreign matter can dramatically reduce intake. If the bunk is completely clean in the mornings and there is little or no dirt present, sweeping the bunk once weekly should be sufficient. If the feeding strategy is to target 3% to 5% of daily feed refusal, then bunks must be cleaned daily. In addition, the area where the cows stand to eat must be clean. This not only cuts down on foot problems, but also encourages feed consumption.

Bunk Space
Bunk space should be between 18" and 30" per cow, depending on the number of feedings during the day, the size of cows, and the bulk of the ration. If bunk space is smaller, feedings will need to be more frequent to stimulate DMI. Feeding cows in a natural grazing position (ground level bunk) encourages them to eat longer, and reduces feed tossing. The floor of the bunk must be smooth. Cows will lick the bunk and a rough surface will often cause a reduction in intake by simply making the cows' tongues sore.

Ration Mixing
If not done properly, the quality and time of feed mixing can lead to acidosis. With high-quality hays, it is possible to mix too long, breaking down fiber particles and reducing the effective fiber content of the ration. If the level of effective (chewable) fiber is inadequate there is a high potential for inadequate rumination and rumen buffering and, thus, for acidosis. Conversely, if the ration is not mixed sufficiently there is the potential for inconsistent (segregated) delivery of the forage and grain when feeding out the mixer down the bunk line. A simple rule of thumb is to mix for one minute per each 1,000 lb of feed. Also, it might be necessary to change the order of adding ingredients in the mixer. Many feeders put hay in the mixer first to allow it time to break down. However, a high-quality hay can rapidly become too short, reducing its contribution in effective fiber. Tools such as the Penn State Particle Size Separator can be used to monitor the particle length of the mixed ration.

Ration Moisture
The moisture content of the ration should be monitored carefully. Consumption is best when ration moisture is between 35% and 50%. Dry rations are usually not as palatable and are more easily sorted than wetter mixes. It is not uncommon to see an increase of two lb in DM intake simply by adding moisture. This can be true for rations containing silage as well. Sometimes adding as much as 15% to 20% water to the final mix makes the ration more palatable, especially in the summer when it dries out between feedings. On the other hand, a ration containing more than 50% moisture from fermented feed can reduce DM intake. Sometimes it is necessary to experiment with a TMR to determine the best moisture level for maximum and uniform consumption of the ration.

Summary
 Proper feeding management is key to optimum feed intake and nutrient conversion. The goal of good feeding management is to ensure that a well- formulated ration continues to remain well-balanced to the point of consumption by the cow. This means that processing and mixing of the feed must be proper and that segregation of grains and forages in the feedbunk must be limited. Carbohydrate intake must remain balanced through time ..... that is, grains and forages must be delivered and consumed in consistent amounts and in similar patterns with each feeding every day. This requires that feed delivery and consumption be carefully monitored (and documented). In addition, ration changes, especially feed increases, should be made smoothly and judiciously.

 

 

 

 

ADM Alliance Nutrition, Inc. , a wholly owned subsidiary of the Archer Daniels Midland Company