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 were 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 paper 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 (Grum et al., 1996; Drackley, 1999; Drackley et al., 2001, 2005; Dann et al., 2005, 2006; Douglas et al., 2006; Loor et al., 2005, 2006). Our research drew both from our ideas and observations as well as from field experiences by individuals such as Dr. Gordie Jones and Dr. Peter Drehmann. The data we have collected demonstrate that cows fed even moderate-energy diets (0.68–0.73 Mcal NEL/lb DM) will easily consume 40 to 80% 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 overconsumption 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 (Douglas et al., 2006; Dann et al., 2006). 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 (Douglas et al., 2006; Janovick Guretzky et al., 2006). From a basic-science standpoint, there are alterations in cellular (Litherland et al., 2003) and gene-level responses (Loor et al., 2005, 2006) that potentially explain many of the changes at cow level.
Our data demonstrate that allowing dry cows to consume more energy than required, even if cows do not become noticeably overconditioned, 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. Humans differ in their tendencies to accumulate fat in different locations, and central obesity is a greater risk factor for disease. Similarly, cows might also vary in the degree to which they accumulate fat internally. In many cases, the mechanisms we have been studying in dry cows are similar to those from human medical research on obesity, type II diabetes, and insulin resistance.
Other research groups around the United States (Holcomb et al., 2001) and in other countries (Agenas et al., 2003; Kunz et al., 1985; Rukkwamsuk et al., 1998) have reached similar conclusions about the desirability of controlling energy intake during the dry period. Our work has extended the ideas to show that overconsumption of energy is common even when feeding typical dry period diets thought to be “safe” and that this may be a predisposing factor to poor health. We also have extended the idea of the high-straw, low-energy ration as a simple and practical approach to achieve the control of energy intake.
Our solution to the potential for cows to over-consume energy is to formulate rations of relatively low energy density (0.59–0.63 Mcal NEL/lb DM) 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 they consume all they can eat. We have termed this the “Goldilocks diet” (Drackley and Janovick Guretzky, 2007) 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.
It is critical that the straw or other roughage actually be consumed in the amounts desired. If cows sort out the straw or other high bulk ingredient, then they will consume too much energy from the other ingredients, and the results may be poor. A total mixed ration (TMR) is by far the best choice for implementing high-straw diets to control energy intake. Some TMR mixers can incorporate straw without pre-chopping and without overly processing other ingredients, but many mixers cannot. Straw may need to be pre-chopped to lengths of 2 inches or less to avoid sorting by the cows.
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 (Janovick Guretzky et al., 2006).
- Field survey data collected by the Keenan company in Europe (courtesy of D. E. Beever, Richard Keenan and Co., Borris, Ireland) 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%. In addition, the change decreased milk fevers by 76%, retained placentas by 57%, displaced abomasum by 85%, and ketosis by 75%. 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 United States.
- 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 not to 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 (Janovick Guretzky et al., 2006) 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 (Dann et al., 2006; Janovick Guretzky et al., 2006) than in cows fed high-energy close-up diets (Grummer et al., 2004). Single-group systems would have the advantage of eliminating one group change, which may decrease social stressors as described by University of Wisconsin researchers (Cook, 2007). 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 (NEL of 0.57−0.60 Mcal/lb DM) so that cows do not over-consume energy (Dann et al., 2006). 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 content, starch content, and feeding characteristics.
The NEL requirement for 1500-lb 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 DM basis.
- Dry matter intake: 25 to 27 lb per day. For far-off cows, intakes by individual cows have often exceeded 30 lb DM per day.
- Energy density: 0.59–0.63 Mcal NEL/lb DM (discussed in more detail in a later section).
- Protein content: 12 to 14% of DM as CP; >1,000 g/day of metabolizable protein as predicted by the NRC (2001) model or CNCPS/CPM Dairy model.
- Starch content: 12 to 16% of DM.
- Forage NDF: 40 to 50% of total DM, or 10 to 12 lb daily (0.7 to 0.8% of body weight). 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: <55% (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% magnesium (minimum), 0.35–0.40% sulfur, potassium as low as possible, a DCAD of near zero or negative, 0.27% phosphorus, and at least 1,500 IU of vitamin E. Recent data suggests that calcium does not have to be increased beyond 0.6% of DM (Lean et al., 2006).
An example formulation is included in Table 1, from a recently completed experiment by our group (Janovick Guretzky et al., 2006). The example is for the far-off dry cow group, but the close-up diet was essentially identical except for the addition of anionic salts.
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 ½ to 2 lb 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.
Deciphering NEL Values
The NEL value specified for the same diet may vary considerably depending on method used to derive the value. While we have used NEL widely to formulate and evaluate high-straw, low-energy diets, nutritionists, veterinarians, and producers have expressed confusion on how to arrive at the “correct” NEL content of the rations. Because of the confusion, it may be better to focus on providing the recommended intakes of forage NDF (10-12 lb/day) as a primary guideline for achieving the correct energy density. Nevertheless, NEL values are important and useful if applied and interpreted carefully.
In calculating NEL values, some confusion has resulted from the changeover to the NRC (2001) equations and calculation methods, and some is related to differences in how feed analysis laboratories calculate and report NEL values. Those working to formulate and monitor the rations must use consistent units for evaluating dietary NEL density to avoid confusion. Moreover, users should realize that it is difficult to compare NEL values across locations and laboratories, so a consistent system within a farm or nutrition practice is more important.
An example of the potential confusion in using NEL values for high-straw, low-energy rations is shown in Table 1. The diet was fed to one group of cows and heifers in our most recently completed experiment (Janovick Guretzky et al., 2006). Feed ingredients were sampled weekly, formed into monthly composites, and analyzed by Dairy One Laboratory (Ithaca, NY) using wet chemistry techniques. Using the actual measured cow variables and analyzed feed composition, we compared the NEL density of the ration calculated four different ways. The value for the total diet calculated by the NRC (2001) model was 0.62 Mcal/lb DM. By using the analytical values for monthly composites of feed ingredients in the Cornell Net Carbohydrate and Protein System (version 5.0), the comparable NEL value was 0.59 Mcal/lb. If we used the NEL values from Dairy One for individual ingredients to additively calculate the total dietary NEL density, the value was 0.55 Mcal/lb DM. However, if we used the values for individual ingredients provided by Dairy One as “NRC values” for dry cows, the total diet NEL was 0.67 Mcal/lb DM! Why the large discrepancy? Which is “correct”?
The NEL value is technically correct only for the feed that a cow actually eats (NRC, 2001) because ingredients in a diet influence rumen digestibility of other ingredients, some positively and some negatively. A classic example is that concentrates added to a diet decrease digestibility of the NDF components in forages by changing the rumen environment. Consequently, the NEL density of a diet cannot be determined accurately by adding together the calculated NEL values of individual ingredients. The NEL value of an individual feed ingredient is only correct if it is fed as the only feed ingredient to a cow, which of course is uncommon.
In addition, the digestibility of the dietary DM decreases as total feed intake increases. This decrease is more pronounced for the NDF fraction than for starch and is greater for grass-type forages than legumes. The NRC incorporates a standard reduction of 4 percentage units digestibility for each multiple of maintenance intake. Because different components of the diet are affected differently by the intake effect, Van Soest (Cornell University) devised a variable discount system. These discounts are used by Dairy One, for example, to report an NEL value at 3× maintenance, which would be equivalent to the intake needed to produce about 66 lb of milk (see http://www.dairyone.com/Forage/FactSheet/NRC_201_Energy_Values.htm. and http://www.dairyone.com/Forage/Newsletters/199903.pdf). Because the NEL value of straw is severely penalized by the Van Soest variable discount system, the calculated value of the diet is considerably lower than the NRC-model value for the total ration (Table 1). On the other hand, using the laboratory values assigned to individual ingredients by the laboratory using NRC principles and then reconstructing an “average” value of the ration overestimates the NEL density relative to the value determined for the total diet as consumed using the NRC (2001) model.
An alternative approach is to use net energy for maintenance (NEM) values instead of NEL. The NEM of a ration should, by definition, be equal to NEL at maintenance intakes (NRC, 2001). When we used NEM provided by Dairy One for individual ingredients to calculate energy values for the diet shown in Table 1, the total ration NEM (0.60 Mcal/lb DM) was close to the NEM value calculated for the total diet (0.62) by the NRC (2001) model.
The bottom line is that those formulating and monitoring diets must be consistent in which energy and laboratory units are being applied and realize that comparison of dietary energy values across studies, laboratories, or farms must be done carefully and with understanding of how the values were derived. Using the assigned NEL values from analytical laboratories may not be appropriate for dry cows fed mixed diets. Values for NEL of the total diet calculated by using the NRC (2001) or CNCPS/CPM models will always be more accurate predictors. Use of NEM values for individual ingredients to calculate an NEM value for the total diet may be the most accurate unit for reconstructing a total diet value from individual analyses.
Practices Important for Success
Three factors are critical to successfully implement this approach: 1) prevention of sorting, 2) ensuring continuous and non-crowded access to the TMR, and 3) careful monitoring of 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. One simple way to evaluate sorting is to shake out the TMR with the Penn State box and then repeat the analysis on the feed refusals the next day. Results should not differ by more than 10% from TMR to refusal. Another way to monitor sorting is to collect samples of the feed refusal from several areas of the feed line and have it analyzed for the same chemical components as the TMR fed. Again, composition of NDF, CP, and minerals should not vary by more than 10% between ration and refusal if cows are not sorting. If cows sort the straw, some cows will be consuming a higher-energy diet than formulated, and some (the more timid cows) will be left with a much lower quality ration than desired. Herds in which sorting is a problem will be characterized by pens of dry cows that range widely in body condition: some will be over-conditioned and some under-conditioned, while of course some may be “just right.”
Another common pitfall is poor feed bunk 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.
As mentioned earlier, the combination of straw and corn silage, along with other lactation ration ingredients, works well because of the complementary features of the components in the total diet. Straw has many desirable characteristics that seem to improve health and digestive dynamics in the rumen. The slow digestion and passage rate of straw certainly seems to be important in prevention of DA. We believe that the control of energy intake is a critically important factor in maintaining a more constant energy intake during the dry period and in preventing other disorders around calving such as ketosis and fatty liver.
Whether other low-energy ingredients will produce the same desirable results remains uncertain. We are not aware of research that has compared other low-energy ingredients such as poor-quality hay, oat hulls, cottonseed hulls, corn stalks, soybean residue, or flax shives to straw or to conventional rations, although we have anecdotal reports from producers and nutritionists with varying reports of success. With roughage-type materials, the key consideration is uniform processing and palatability so that cows do not sort and the formulated profile of nutrients is actually consumed. For concentrate-type or finely ground ingredients, energy content is low, but particle size is so small that rate of passage can be too fast, allowing particles to escape more quickly even though they are not digested. In this case, DMI by the cows may increase so that total energy intake still exceeds requirements considerably.
Good-quality straw is a consistent (but low) source of nutrients, although its composition still can be variable (NRC, 2001). Table 2 shows means, standard deviations, and ranges for straw samples over two years during two recent experiments from our group (Dann et al., 2006; Janovick Guretzky et al., 2006). The mean values are close to those reported in NRC (2001), although CP was lower and NDF higher in our samples. Also of note, analyzed concentrations of potassium and sodium were considerably lower than means reported by NRC (2001).
Just because straw or other low-energy ingredients are “low quality” by conventional standards of evaluation based on protein or energy content does not mean that other measures of “quality” can be ignored. Straw or other feeds that are moldy, severely weather-damaged, or have fermented poorly should not be fed to dry cows, especially the close-ups.
Comparisons of high-straw, low-energy diets with conventional diets in cows of widely differing body condition scores are not available. In the field, the diets seem to work well in both thin and fat cows. In fact, many producers have concluded that these diets are the best way to manage obese cows through calving to minimize the usual problems expected with fat cows.
High-straw, low-energy rations are exciting for their potential to markedly improve health during the transition period. The key concept is to strive to meet the requirements of cows for energy and all other nutrients but not to allow cows to exceed their requirements for energy by large amounts for the duration of the dry period. Provided that these high-straw, low-energy rations are formulated, mixed, and delivered properly, results have been positive. Research and field observations indicate that the rations result in better energy balance after calving, with subsequent improvements in health. Milk production is maintained, and field observations suggest that reproductive success may be improved also, although data are lacking. Research is needed to explore other low-energy, bulky ingredients as options to straw.
Agenäs, S., E. Burstedt, and K. Holtenius. 2003. Effects of feeding intensity during the dry period. 1. Feed intake, bodyweight, and milk production. J. Dairy Sci. 86:870-882.
Cook, N. B. 2007. Makin’ me dizzy – pen moves and facility designs to maximize transition cow health and productivity. Pp. 161-171 in Proc. 8th Western Dairy Mgt. Conf., Reno, NV. Oregon St. Univ., Corvallis.
Dann, H. M., N. B. Litherland, J. P. Underwood, M. Bionaz, A. D’Angelo, J. W. McFadden, and J. K. Drackley. 2006. Diets during far-off and close-up dry periods affect periparturient metabolism and lactation in multiparous cows. J. Dairy Sci. 89:3563-3577.
Dann, H. M., D. E. Morin, M. R. Murphy, G. A. Bollero, and J. K. Drackley. 2005. Prepartum intake, postpartum induction of ketosis, and periparturient disorders affect the metabolic status of dairy cows. J. Dairy Sci. 88:3249-3264.
Douglas, G. N, T. R. Overton, H. G. Bateman, II, H. M. Dann, and J. K. Drackley. 2006. Prepartal plane of nutrition, regardless of dietary energy source, affects periparturient metabolism and dry matter intake in Holstein cows. J. Dairy Sci. 89:2141-2157.
Drackley, J. K. 1999. Biology of dairy cows during the transition period: The final frontier? J. Dairy Sci. 82:2259-2273.
Drackley, J. K., H. M. Dann, G. N. Douglas, N. A. Janovick Guretzky, N. B. Litherland, J. P. Underwood, and J. J. Loor. 2005. Physiological and pathological adaptations in dairy cows that may increase susceptibility to periparturient diseases and disorders. Ital. J. Anim. Sci. 4:323-344.
Drackley, J. K., and N. A. Janovick Guretzky. 2007. Controlled energy diets for dry cows. Pp. 7-16 in Proc. 8th Western Dairy Mgt. Conf., Reno, NV. Oregon St. Univ., Corvallis.
Drackley, J. K., T. R. Overton, and G. N. Douglas. 2001. Adaptations of glucose and long-chain fatty acid metabolism in liver of dairy cows during the periparturient period. J. Dairy Sci. 84(E. Suppl.):E100-E112.
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Loor, J. J., H. M. Dann, R. E. Everts, R. Oliveira, C. A. Green, N. A. Janovick-Guretzky, S. L. Rodriguez-Zas, H. A. Lewin, and J. K. Drackley. 2005. Temporal gene expression profiling of liver from periparturient dairy cows reveals complex adaptive mechanisms in hepatic function. Physiol. Genomics 23:217-226.
Loor, J. J., H. M. Dann, N. A. Janovick Guretzky, R. E. Everts, R. Oliveira, C. A. Green, N. B. Litherland, S. L. Rodriguez-Zas, H. A. Lewin, and J. K. Drackley. 2006. Plane of nutrition pre-partum alters hepatic gene expression and function in dairy cows as assessed by longitudinal transcript and metabolic profiling. Physiol. Genomics 27:29-41.
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http://www.dairyone.com/Forage/FactSheet/NRC_201_Energy_Values.htm. Accessed 12/1/06.
http://www.dairyone.com/Forage/Newsletters/199903.pdf. Accessed 12/1/06.
|Item||Amount in ration (DM basis)|
Corn Silage, %
Chopped wheat straw, %
Chopped alfalfa hay, %
Corn grain, ground, dry, %
Soybean meal, solvent, 48% CP, %
Minerals and vitamins, %
Forage NDF, %
NRC Metabolizable protein, g/d at 16.5 lb DMI
NEL, Mcal/lb DMa
NEL, Mcal/lb DMb
NEL, Mcal/lb DMc
NEL, Mcal/lb DMd
NEM, Mcal/lb DMe
aCalculated for the total diet using the NRC (2001) model and analyzed chemical composition for corn silage, wheat straw, alfalfa hay, and concentrate mixture.
bCalculated for the total diet using the CNCPS (version 5.0) model and analyzed chemical composition for corn silage, wheat straw, alfalfa hay, and concentrate mixture.
cCalculated additively using NEL values assigned by Dairy One Laboratory for individual ingredients, using the Van Soest variable discount factors and correct at intake of 3× maintenance.
dCalculated additively using NEL values provided by Dairy One Laboratory using NRC 2001 equations (Ohio State summative equation) for individual ingredients, at intake appropriate for dry cows.
eCalculated using NEM values for individual ingredients as specified by Dairy One Laboratory.
|DM, % as fed||93.3||0.82||84.5||91.2|
|CP, % of DM||3.8||0.83||5.3||2.4|
|Soluble protein, % of CP||44.2||9.6||65.0||25.0|
|NDF, % of DM||79.6||3.7||85.2||69.9|
|ADF, % of DM||53.3||2.9||59.0||45.8|
|NFC, % of DM||11.6||3.0||19.2||6.8|
|NEM, Mcal/lb DM||0.35||0.06||0.43||0.12|
|Ca, % of DM||0.27||0.11||0.57||0.08|
|P, % of DM||0.08||0.03||0.14||0.05|
|Mg, % of DM||0.12||0.04||0.26||0.09|
|K, % of DM||1.30||0.12||1.53||0.95|
|S, % of DM||0.07||0.03||0.18||0.04|
|Na, % of DM||0.02||0.01||0.06||0.01|
|Fe, ppm of DM||117||68||303||53|
|Zn, ppm of DM||16||11.6||59||7|
|Cu, ppm of DM||8||4.1||18||4|
|Mn, ppm of DM||75||15.3||119||51|
|1Values are from 21 monthly composite samples from two experiments (Dann et al., 2006; Janovick Guretzky et al., 2006) analyzed by wet chemistry techniques at the same laboratory (Dairy One, Ithaca, NY).|
James K. Drackley and Nicole A. Janovick-Guretzky
University of Illinois at Urbana-Champaign
Reprinted from Proceedings of the 4-State Dairy Nutrition and Management Conference, June 13-14, 2007, Dubuque, Iowa USA