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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:
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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.
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