Many dairy operations large and small continue to be plagued by a high incidence of metabolic disorders and infectious diseases around calving. Turbulent transitions increase health care expenses, decrease milk production, impair reproductive performance and result in premature culling or death. Farm profitability and animal well-being both suffer. Despite many years of research and field emphasis, practical management strategies to minimize health problems while still promoting high milk production have remained elusive.

Over the last 20 years, higher energy and nutrient density rations have been fed during the close-up (pre-fresh) period, generally beginning around three weeks before expected calving. This approach was designed on the basis of research showing advantages in adaptation of the rumen microbial population and rumen papillae to higher nutrient diets fed after calving, decreased body fat mobilization and fat deposition in liver, and maintenance of blood-calcium concentrations.

Although each of these ideas was sound and based on good research data, the ability of higher-energy, close-up or “steam-up” diets to minimize production diseases in research trials and field experience has been disappointing and frustrating. Overall, data fail to demonstrate that steam-up diets reliably and repeatedly improve production, body condition, reproduction or health after calving.

We have been frustrated by this lack of success in both research and field settings and have searched for a better approach to dry cow nutritional management. The concepts presented in this [article] in many ways are nothing new, as they center on formulating dry cow rations to dietary energy densities that were established many years ago by the National Research Council (NRC). Rethinking what these data and previous knowledge tell us about dry cows has led us to a new interpretation relative to the existing dogma and to develop a practical system suitable for modern dairy management practices on both small and large dairies.

Controlled energy intake during the dry period
Our research group has investigated whether controlling energy intake during the dry period might lead to better transition success. Our research drew both from our ideas and observations as well as from field experiences. The data we have collected demonstrates that cows fed even moderate-energy diets will easily consume 40 to 80 percent more NEL than required during both far-off and close-up periods. Cows in these studies were all less than 3.5 body condition score at dry-off, were housed in individual stalls, and were fed diets based on corn silage, alfalfa silage and alfalfa hay with some concentrate supplementation.

We have no evidence that the extra energy and nutrient intake was beneficial in any way. More importantly, our data indicate that allowing cows to over-consume energy to this degree may predispose them to health problems during the transition period if they face additional management challenges that create stress responses or limit feed intake.

We have collected a variety of data indicating that prolonged over-consumption of energy during the dry period can result in poorer transitions. These data include whole-animal responses important to dairy producers such as lower post-calving dry matter intakes and slower starts in milk production. We also have demonstrated that overfeeding results in negative responses of metabolic indicators, such as higher nonesterified fatty acids (NEFA) in blood and more triglyceride or fat in the liver after calving.

Our data demonstrate that allowing dry cows to consume more energy than required, even if cows do not become noticeably over-conditioned, results in responses that would be typical of overly fat cows. Because energy that cows consume in excess of their requirements must either be dissipated as heat or stored, we speculate that the excess is accumulated preferentially in internal adipose tissue (fat) depots in some cows. The NEFA and signaling molecules released by some of these visceral adipose tissues go directly to the liver, which may cause fatty liver, subclinical ketosis and other secondary problems with liver function.

Our solution to the potential for cows to over-consume energy is to formulate rations of relatively low-energy density that cows can consume free-choice without greatly exceeding their daily energy requirements. Note that we are not proposing to limit energy intake to less than cows’ requirements, but rather to feed them a bulky diet that will only meet their requirements when cows consume all they can eat. We have termed this the “Goldilocks diet” because, like the story of Goldilocks and the three bears, we don’t want the cow to consume too much or too little energy, but rather just the right amount to match her requirements.

To accomplish the goal of controlled energy intake requires that some ingredient or ingredients of lower-energy density be incorporated into diets containing higher-energy ingredients such as corn silage, good-quality grass or legume silage or high-quality hay. Cereal straws, particularly wheat straw, are well-suited to dilute the energy density of these higher-energy feeds, especially when corn silage is the predominant forage source available. Lower- quality grass hays also may work if processed appropriately, but still may have considerably greater energy value than straw and thus are not as effective in decreasing energy density.

We are aware of no controlled data comparing different types of straw, but it is the general consensus among those who have years of experience using straw that wheat is preferred. Barley straw is a second choice, followed by oat straw. While reasons for these preferences are not entirely clear, wheat straw is more plentiful, is generally fairly uniform in quality, and has a coarse, brittle and hollow stem that processes easily, is palatable and seems to promote desirable rumen fermentation conditions. Barley straw lacks some of these characteristics. Oat straw is softer and as a result does not process as uniformly. In addition, oat straw generally is somewhat more digestible and thus has greater energy content.

Advantages and beneficial outcomes
Based on our research and field observations, adoption of the high-straw, low-energy TMR concept for dry cows might lead to the following benefits:

• Successful implementation of this program essentially eliminates occurrence of displaced abomasum.

This may result from the greater rumen fill, which is maintained for some period of time even if cows go off feed for some reason, or from the stabilizing effect on feed intake.

• Field survey data collected by the Keenan company in Europe show strong indications of positive effects on health.

In 277 herds (over 27,000 cows) in the United Kingdom, Ireland, France and Sweden, changing to the high-straw low-energy TMR system decreased assisted calvings by 53 percent. In addition, the change decreased milk fevers by 76 percent, retained placentas by 57 percent, displaced abomasum 85 percent and ketosis by 75 percent. Using standard values for cost of these problems, the average increase in margin per cow in these herds was $114 just from improved health alone. While these are certainly not controlled research data, they are consistent with the results in our research as well as field observations in the U.S.

• The same sources of observational data indicate that body condition, reproductive success and foot health may be improved in herds struggling with these areas.

• Although data are limited, milk production appears to be similar to or slightly lower than results obtained with higher-energy close-up programs.

There is some evidence that persistency may be improved, with cows reaching slightly lower and later peak milk. Therefore, producers should be careful to not evaluate the system based on early peaks and should look at total lactation milk yield, daily milk and, over time, indices of reproduction and other non-milk indicators of economic value.

• Straw and corn silage generally are lower in potassium and thus help control the dietary cation-anion difference (DCAD) without excessive addition of anionic salt mixtures.

• The program may simplify dry cow management and ration composition in many cases.

• Depending on straw cost, the ration likely will be no more expensive than the average cost of far-off and close-up diets, and could be cheaper where straw is plentiful.

Single-diet dry cow management?
Our most recent research as well as considerable field experience indicates that a single-diet dry cow program can be successful using these principles. Dry matter intakes remain more constant as cows approach calving when fed the high-straw low-energy diets than in cows fed high-energy close-up diets. Single-group systems would have the advantage of eliminating one group change, which may decrease social stressors. Single-group management may work particularly well for producers managing for shorter dry periods.

A variation is to maintain far-off and close-up diets, with essentially the same diet for both except that a different concentrate mix or premix is used for the close-ups, which may incorporate anionic salts, extra vitamins and minerals, additional protein or selected feed additives. The optimal high-forage, low-energy dry cow ration will contain the primary forages and grains to be fed in the lactation diet, but diluted with straw or low-quality forage to achieve the desired energy density. In this way, the rumen still can be adapted to the types of ingredients to be fed after calving without excessive energy intake during the dry period.

If producers desire to maintain the conventional two-group or “steam-up” philosophy for dry cow feeding, our research has shown that the most critical factor is to ensure that the energy density of the far-off dry period diet is decreased to near NRC (2001) recommendations so that cows do not over-consume energy. In this research, wide extremes in close-up nutrient intake had very little effect compared with the effect of allowing cows to consume excess energy during the far-off period.

Specifications for dry period diets
The controlled energy system works best for producers who are relying on corn silage as a primary forage. The combination of straw and corn silage is complementary for many reasons, including energy content, low potassium contents, starch content and feeding characteristics. The NEL requirement for 1,500-pound Holstein cows is between 14 and 15 Mcal per day (NRC, 2001). Some suggested guidelines for formulation of controlled energy diets to meet that requirement are as follows, on a total ration dry matter (DM) basis:

• Dry matter intake: 25 to 27 pounds per day. For far-off cows, intakes by individual cows have often exceeded 30 pounds DM per day.

• Energy density: 0.59 to 0.63 Mcal NEL per pound DM.

• Protein content: 12 to 14 percent of DM as crude protein (CP); greater than 1,000 grams per day of metabolizable protein as predicted by the NRC (2001) model or CNCPS/CPM Dairy model.

• Starch content: 12 to 16 percent of DM.

• Forage NDF: 40 to 50 percent of total DM, or 10 to 12 pounds daily (0.7 to 0.8 percent of bodyweight). Target the high end of the range if more higher-energy fiber sources (like grass hay or low-quality alfalfa) are used, and the low end of the range if straw is used.

• Total ration DM content: less than 55 percent (add water if necessary). Additional water will help hold the ration together and improve palatability.

• Follow standard guidelines for mineral and vitamin supplementation. For close-ups, target values are 0.40 percent magnesium (minimum), 0.35 to 0.40 percent sulfur, potassium as low as possible, a DCAD of near zero or negative, 0.27 percent phosphorus and at least 1,500 international units (IU) of vitamin E.

As long as the lactation diet is formulated appropriately, there seems to be little difficulty in transitioning to the lactation diet immediately after calving. Many producers have found that inclusion of 0.5 to 2 pounds of chopped straw in the lactation diet improves rumen function and animal performance, particularly when physical fiber is borderline adequate. Addition of the straw postpartum also may help to ease the transition from the lower-energy dry cow diet.

Practices important for success

Three factors are critical to successfully implement this approach:
1. prevent sorting

2. ensure continuous and non-crowded access to the TMR

3. carefully monitor DM content and attention to detail

Where “train-wrecks” have been reported, one or more of these factors has been faulty, not the dietary approach itself.

The straw must be chopped into a particle size that cows will not sort out of the ration. In general, this means less than 2-inch particles. If the straw is pre-chopped, an appropriate chop is indicated by having about one-third of the particles in each of the three fractions of the Penn State shaker box. Because of the bulky nature of straw and the resulting TMR, producers may think that cows are sorting excessively when they are not. To verify that cows are not sorting, the feed refusals should be monitored carefully and compared to the original TMR. Composition of NDF, CP and minerals should not vary by more than 10 percent between ration and refusal if cows are not sorting.

Another common pitfall is poor feedbunk management that limits the ability of cows to consume feed ad libitum. Because of the bulky nature of the diet, cows may have to spend more time eating to consume enough feed to meet energy and nutrient requirements. Bunk space must be adequate and feed pushed up frequently. If feed is not pushed up, cows likely will not be able to consume what they need to meet requirements.

Other common problems arise when the DM content of straw, hay and silages changes markedly from assumed values. This may happen, for example, if the straw is rained on or the DM content of silage changes without the feeders knowing it. Changes in DM of the ingredients mean changes in the DM proportions of the total diet unless the mix is corrected.Thus, energy intake may increase or decrease relative to the target, and producers may experience a rash of calving-related health problems until the situation is corrected.

While the nutritional concepts of these rations are simple, the approach and implementation are not problem-free. Attention to detail is a must. The system is not an “easy” or a lazy approach to dry cow care. When implemented correctly, results have been exceptional. However, high-straw, low-energy diets are not remedies for poor feeding management or bad facilities. Applied in these situations, results may be poor. PD

References omitted but are available upon request at editor@progressivedairy.com

—Excerpts from 2007 Penn State Dairy Cattle Nutrition Workshop Proceedings

James K. Drackley and Nicole A. Janovick-Guretzky, Department of Animal Sciences, University of Illinois