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Dairy Update Issue 121, October 1995

Management of TMR Feeding Programs

James G. Linn, University of Minnesota, St. Paul

The goal of any feeding program is to provide the correct amount and balance of nutrients to cows at the proper time to achieve optimum production, reproductive efficiency and profitability. No single system is correct for all dairy producers; however, the emerging feeding method of choice for both small and large dairy herds is a Total Mixed Ration (TMR). The nutritional advantages of a TMR over individual component feeding programs are:

1. Elimination of cow selectivity of individual feeds.
2. Capability of accurately determining dry matter (DM) intake of cows.
3. Overall better control of feeds offered and consumed by cows and, thus, better control of feed costs.
4. Ability to use a wider variety of feedstuffs including less palatable feeds and commodity feeds.

To be an efficient and effective feeding program, the TMR has to be managed correctly. Critical management factors include: 1) knowing and adjusting for changes in forage DM content; 2) good feed bunk management; 3) correct grouping of cows; 4) continuous monitoring of DM intake; 5) good mixing of feeds and correct ration formulation. This paper presents some guidelines on managing these critical factors for the successful feeding of TMRs on dairy farms.

Knowing the amount of DM cows are consuming is essential for optimization of milk production. The nutrients contained in the DM, especially energy and protein, are the major factors influencing milk production and body weight change during the lactation. Without good DM intake information, correctly formulating rations to meet nutrient needs for production is difficult. Underfeeding of nutrients results in a loss of production while overfeeding increases feed costs.

An example of a feed data collection sheet for on-the-farm use is in Figure 1. Daily amounts of feed delivered and consumed should be recorded. Daily DM intakes should be compared to those used in formulation of the ration or possibly standard prediction equations like those shown below (M. May, Ph.D. thesis, University of Minnesota):

2nd lactation and older cows:
DM intake (kg/d) = .959 + 1.051 × wk – .042 × wk² + .0005 × wk³ + .012 × BW (kg) + .354 × 4% fat milk (kg/d) – 1.966 × milk fat % + .941 × milk protein %

1st lactation cows:
DM intake (kg/d) = –2.12 + .882 × wk – .031 × wk² + .0003 × wk³ + .016 × BW (kg) + .351 × 4% fat milk (kg/d) – 1.51 × milk fat % + .752 × milk protein %

wk = week of lactation

(kg/d × 2.205 = lb/d)

If the actual or on-farm DM intake and the DM intake used to formulate the ration differ by more than 5%, the reasons for the difference need to be determined. Consumption rates above the predicted amount are of less concern than those below; however, they may indicate errors in weighing feeds. Reformulation of rations should occur after differences between on-farm and ration predicted DM intakes are verified and corrected.

Feeds with less than 75% DM that are incorporated into TMRs should be checked weekly for actual DM content. Correctly formulated TMRs can quickly become unbalanced when changes in feed DM occur and rations are not adjusted for the change. Table 1 illustrates how a change in corn silage DM from 35 to 45% can change amounts of DM fed and nutrient amounts consumed. A change in CP intake of only .1 lb translates into a milk protein change of 1 lb. In high producing rations with minimum fiber, a decrease in forage DM could resulty in more off-feed and acidosis problems. Accurate daily recording of feed intakes is needed to identify when feed DM changes occur.

The goal in feed bunk management is to obtain maximum DM intake by ensuring that a fresh, palatable, balanced TMR is available to all cows. As herd productions increase, DM intake is the key factor in maintaining production. The following are various aspects of feed bunk management.

1. Feed should be uniformly spread throughout feed bunk.
2. Cows should have a minimum of 18 inches and up to 30 inches feeding space.
3. Feed sorting should be evaluated, and feed refusals should be scored based on uniformity. Feed refusals should be very close in appearance and composition to the TMR fed if no sorting of feed occurred. Be particularly aware of forage or large particle sorting in feed bunks.
4. Feed refusals should be cool and smell fresh. Hot, moldy feed refusals indicate an extra feeding may be necessary.
5. Total feed refusals should be about 5% of total fed and removed daily.
6. Push feed up into managers 2 to 3 times during a 24 hour period.
7. Feed bunks should be empty no more than 2 to 3 hours per day.
8. Observe cows when feed is delivered. Sick or lame cows tend to hang back and not come to the bunk when fresh feed is offered.
9. Feed bunks should have a smooth surface for ease in cleaning and promote better feed consumption.
10. Cows should be eating with their head down in a grazing position for best feed intake and saliva flow. This position also discourages feed tossing.
11. Check water supplies daily for availability and freshness.
12. Feed deliveries in early morning or late afternoon coincide with times cows most frequently consume feeds.

The number of groups and the number of different rations to be fed are independent decisions. The number of groups is usually determined by management decisions such as reproduction, slow milkers and facility design and not by feeding or nutrient requirements. Small herds, less than 100 cows and particularly those housed in tie-stall barns, often are fed one TMR regardless of milk production or body condition. This has the advantage of simplifying mixing, reducing feeding labor and eliminates milk production drops which often occurs when cows are switched from one TMR to another. The disadvantages to one group TMR feeding is feed costs increase, fat or overconditioned cows are likely especially if breeding problems occur and there is limited flexibility in the use of low quality feeds.

In larger herds, greater than 100 cows, the minimum number of recommended milk cow feeding groups based on nutrient requirements and DM intake is as follows:

1. Fresh cows. Cows are placed in this group immediately after calving and remain there for 1 to 2 weeks or until cows are eating well. This group should have a low cow density with ample bunk space per cow to reduce stress and competition for feed and stalls. This group also may be a hospital or sick cow group in some herds.
2. High producing older cows. These cows are fed a high production TMR throughout lactation or until body condition or milk production dictates movement to a lower production ration.
3. High production first calf heifers. Lactating heifers tend to eat smaller meal sizes and more frequent but shorter duration meals than older lactating cows. First lactation cows are often more timid and, thus, easily dominated by older cows as well. Separation of first lactation heifers from older cows, especially the first 200 days of lactation, reduces stress and encourages feed intake. First lactation heifers also consume less DM, about 15 to 20% less, than older cows at the same milk production necessitating a different formulation than older cows.
4. Low or excess body condition group. Both heifers and older cows can be moved into this group when body condition becomes excessive. This group also can be used for cows with extended lactations due to breeding problems.

Regardless of herd size, all herds should have at least two separate dry cow groups.

1. Far off dry cows. One or 2 groups may be necessary depending on body condition. Cows dried off in excess body condition (score of 3.75 or greater, 1=thin, 5=fat) should be on a maintenance ration for the first 30 to 45 days of the dry period. Cows in adequate (3 to 3.25) or thin (<3) body condition at dry off should be fed a ration to gain about 1.8 lb/day during the first 30 to 45 days.
2. Close-up dry cows. This group begins to receive some of the ingredients in the lactating TMR starting 14 to 21 days before calving.

The recommended nutrient content of TMRs for cows described under feeding groups is in Table 2. If rations are to be balanced for specific milk productions, the target milk production can be determined by adding the average milk production (lb/day) and the highest milk production (lb/day) of the group or herd of cows and dividing by 2. This results in balancing for a milk production at about the 75th percentile or 1 standard deviation above the average. Lead factors have been developed based on the number of milk cow feeding groups within a herd. For a single production group, balance for a milk production 30% above the average; for 2 production groups, balance for a milk production 20% above the average in each group; and for 3 production groups, balance for a milk production 10% above the average in each group.

This feeding practice is used to deliver additional grain or energy in an inexpensive way to high producing cows. The highest producing older or first lactation heifers are fed an additional 3 to 8 lb of grain per day in two to three meals per day. The advantage is that high cost feed ingredients (e.g., protected fats, high bypass protein supplements, special mineral packs) can be specifically targeted to individual cows. The disadvantage of additional grain feeding is excessive amounts (> 8 lb) can unbalance the TMR reducing fiber and forage intakes.

Another example of partial TMR feeding is to feed 2 to 5 lb of long hay per cow per day separate from the TMR. If hay quality is very good and the hay is evenly distributed in the bunk (or manger), this small amount should not unbalance the TMR.

The frequency of feeding in TMR fed herds is not as important as when individual feed components are fed. Generally, twice a day delivery of TMR to milk cows is the practice on most farms. Once a day feeding is possible in cool weather and when ration heating is not a problem. When rations remain fresh in bunks, increasing feeding frequency will generally not increase total daily DM intake, but it does encourage cows to eat smaller meals more frequently improving feed utilization. (Note: Pushing up feed encourages consumption similar to delivery of fresh feed.) Dry cows and growing heifers can be fed once per day.

Mixer Management

Four points to consider on how well TMRs are mixed with respect to equipment are: 1) accuracy of scales, 2) feed ingredient inclusion amount, 3) mixing time and 4) order of feed ingredient addition to mixers.

1. Scale accuracy - check scale weights monthly. Compare scale weights to feed inventory records. Amounts should be the same except for normal inventory losses.
2. The minimum amount of an ingredient or feed to add to a batch is around 20 lb. Ingredients with smaller inclusion amounts should be mixed together before adding to the TMR.
3. Mixing time varies with feed usage and different mixers. Overmixing is generally more of a problem then undermixing. Mixing TMRs over 5 minutes can reduce forage particle length. Functional or effective fiber can be inadequate in over mixed rations even though formulated ration fiber values are adequate.

Order of ingredient addition can affect mixing. In auger mixers, add long hay first followed by grains, proteins, minerals and silages. Order of ingredient addition is not as important with tumble or drum mixers.

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