The added benefits of feeding an AA balanced diet: Impact during the transition phase.

In the last Tech Note, the added benefits of balancing rations for AA to lower the N load of the diet and improve the efficiency of N utilization by the cow were discussed.

Another benefit often overlooked is balancing rations for AA during the transition period. Methionine plays a key role in the formation of very low density lipoproteins (VLDLs). It is both a building block for the formation of Apoprotein B and a precursor for the synthesis of phosphatidyl choline. VLDL is the key vehicle to transport fat out of the liver. Helping the cow utilize mobilized fatty acids efficiently is important for maintaining a healthy liver and providing other tissues a much needed energy source during the critical first few weeks post-partum. A summary of five trials in which cows were fed increased concentrations of metabolizable Lysine and Methionine during the transition phase showed dairy cows produced an extra five pounds of milk/day, with 0.09% extra protein and 0.1% extra fat (Garthwaite et al, 1998).

Results of a recent transition cow study were reported at the last annual meeting of the American Society of Dairy Science (Osorio et al, 2011) confirmed the importance of amino acid balancing transition cow rations. The protocol consisted of feeding one of three diets from 21 days pre-fresh to 28 days in milk to three groups (15 cows each):

• Control - fed a pre-fresh diet with a Lys:Met of 3.6:1 to a post-fresh diet with a Lys:Met of 3.3:1
• MetaSmart® - same pre-fresh and post-fresh diets as Control with the addition of dry MetaSmart® to bring the Lys:Met to 2.85:1
• Smartamine® M - same pre-fresh and post-fresh diets with the addition of Smartamine® to bring the Lys:Met to 2.85:1

The cows fed the Methionine-enriched diets consumed an average of 5.6 extra pounds/day of feed and increased Energy Corrected Milk by 8.7 pounds during the first 28 days in milk and had less total liver lipid at 21 days post-fresh. There was no difference between the two methionine sources fed regarding intake, Energy Corrected Milk or total liver lipids.

Control (26.9 lb) vs. MetaSmart® and
Smartamine® (32.47 lb) (P = 0.04)

Control (94.3 lb) vs. MetaSmart®
and Smartamine® (103.0 lb) (P = 0.05)

The ADDED Benefits of Using MetaSmart® to Balance for Amino Acids

In the past, Adisseo concentrated its efforts to highlight the importance of feeding an amino acid-balanced diet to improve milk composition, particularly milk protein content. AA formulation guidelines were based on results from extensive University research. However it is now clear that these advantages are only the tip of the iceberg. OneADDED benefit often overlooked is the improvement of the efficiency of nitrogen (N) utilization by the cow. When the ration is properly balanced, the 'N load' of the ration can be reduced without sacrificing milk output, and by doing so, we improve the efficiency of N utilization. This may not seem important at first sight; however, when less N is fed, less is wasted and cost savings can be substantial.

Monitoring responses to formulation change on a farm is often a big challenge. For example; when a ration is AA balanced and as a consequence more grams of metabolizable methionine are provided in the diet, the cow can respond through a combination of milk volume, milk protein and milk fat percent. Therefore, to capture the full impact of the response, Energy Corrected Milk (ECM) is an excellent way to monitor the response with one number.

In a recent publication (Chen, 2011) the researchers fed one group of cows a 16.8% Crude Protein (CP) diet that provided an estimated 2590 grams of metabolizable protein with a Lys:Met ratio of 3.33. Another group of cows were fed a 15.7% CP diet that delivered 2450 grams of metabolizable protein with a Lys:Met ratio of 2.98. In other words, the higher CP ration delivered 140 extra grams of metabolizable protein but the AA profile was unbalanced. The researchers designed the diets in a way that both rations delivered similar grams of metabolizable lysine, but the low CP ration provided six extra grams of metabolizable methionine by including 40 grams of Dry MetaSmart.

Item	16.8% CP w/o MetaSmart	15.7 % CP with MetaSmart
Metabolizable protein, g/d	2590	2450
Metabolizable Lysine, g/d	160	161
Metabolizable Methionine, g/d	48	54
Lys:Met	3.33	2.98
Milk, lb/d	90.8	92.8
Fat, %	3.85	3.93
True Protein, %	3.05b	3.19a
Lactose, %	4.81	4.83
ECM, lb/d	86.9b	90.4a
MUN, mg/dl	13.2a	10.2b
PUN	15.7a	12.2b
Milk N/N intake (N efficiency, %)	30.2b	32.3a

The cows fed the diet with the lower 'N load' produced two extra pounds of milk with better fat and protein percent, such that the cows fed the lower N diet responded with a significant 3.5 lbs of extra Energy Corrected Milk (ECM). These cows also had lower plasma urea N and milk urea N, confirming the better efficiency of N utilization.

Improving the Efficiency of Nitrogen (N) Utilization

Profitable milk production depends on efficient use of dietary protein. The target should be for 30% of Total N ingested to be converted to Productive N and for the Productive N/Urinary N ratio to be greater than 100%.

Typically only 25% of N intake is incorporated into milk protein - in other words 75% is excreted in the urine and feces. Fecal N is relatively constant, thus the extra N consumed by the cow is secreted in the urine which is the most volatile form. Olmos, Colmenero and Broderick found that as cows consume more N, the N secreted in the milk as well as the N secreted in the feces was fairly constant. On the other hand, the N excreted in the urine increased linearly in relation to the intake. The net effect was that the efficiency of N utilization decreased from 36 to 25%. Maximizing N efficiency is not only good for the environment; it is also good for the cow's energy status. It takes 7.2 Kcal of Metabolizable Energy per gram of excess N to convert to urea.

Accurately balancing the rations for Amino Acids will further improve the efficiency of N utilization by lowering N inputs while maximizing milk protein synthesis.

The new CNCPS v6 (incorporated in the AMTS, NDS and other commercial software programs) includes reports that help us monitor how efficient N utilization is in a particular situation.

Excretion
Fecal (lbs)	107
Urine (lbs)	47
Total Manure (lbs)	154
Fecal N (g)	248
Urine N (g)	184
Total Manure N (g)	431
Productive N:Total N	0.36:1		Productive N/Total N > 30%
Productive N:Urinary N	1.29:1		Productive N/Urinary N > 100%
Manure N:Total N	0.64:1

Efficiency of N Utilization (Olmos Colmenero and Broderick, 2006)

What LYS:MET ratios should we be looking for in each model?

Under practical situations it is difficult to formulate to the optimal % of metabolizable Lysine (LYS) and metabolizable methionine (MET) as recommended by Whitehouse et al. (2009). In practice, the levels than can be achieved are closer to 97% of the optimal. The table below gives the practical target formulation levels for LYS and MET for each model.

*97 % of Optimal

There are additional benefits when diets are balanced to optimize milk protein. When LYS and MET are provided in optimal balance, we also improve the efficiency nitrogen utilization. In fact, by concentrating the levels of LYS and MET in metabolizable protein (MP), total MP and crude protein can be reduced. It is not only good for the cow; It is also good for the environment. In the next Tech Note, I will discuss new parameters that can be monitored to track and improve nitrogen utilization.

How to Successfully Balance Dairy Rations for LYS and MET

In the previous SmartMail we examined how feed’s Crude Protein (CP) is partitioned into different fractions by the NRC, CPM and CNCPS models. We also discussed how the biology in each model estimates the grams of metabolizable protein (MP) and its amino acid profile. It has long been recognized that it is not CP that the cow needs to satisfy requirements - it is the grams of amino acids in the MP that count.

Rations should be balanced with the goal of optimizing concentrations of metabolizable lysine (LYS) and metabolizable methionine (MET) in MP and respecting an ideal LYS to MET ratio. Whitehouse et al. (2009) applied the indirect dose-response approach used in the NRC 2001 protein sub-model to determine the optimal concentrations of LYS and MET in MP for not only the NRC but also the CPM and CNCPS models. As can be seen in the table below, the optimal LYS and MET concentrations were different for each model. They are much higher for CPM versus the other two models due to the higher microbial contribution predicted by CPM:



However, in practice, it is often hard to achieve the optimal concentrations of LYS and MET due to restrictions on ingredient availability.

In the next SmartMail, I will discuss target formulation values to aim for when balancing diets for LYS and MET with respect to the three models.

Differences in How Crude Protein is Fractionated Between Models

As models have evolved, the Crude Protein (CP) of an ingredient has been recognized as having different fractions with each fraction having a specific degradation rate (Kd). The relationship of the pool size of each fraction with its specific Kd linked to the rate of passage (Kp) defines the percentage of CP that is degraded in the rumen and the percentage that flows to the small intestine. Tables 1 and 2 give an example of how the CP of solvent soybean meal is partitioned into different pool sizes by the NRC, CPM and the CNCPS v.6.




The impact of how the pool fractions are estimated as well as the different Kds and Kps assigned to each fraction for each model on the estimated RUP (%CP) is of consequence. Using the example of soybean meal*, the estimated RUP is 43.5, 37.4 and 42.1% for NRC, CPM V.3 and CNCPS v.6 respectively. The differences illustrated for soybean meal are generally true for other ingredients such that the same ration evaluated through CPM will have a lower predicted RUP proportion of MP which is offset by a higher microbial protein contribution compared to both NRC and CNCPS.

Currently, in the United States, there are several models using the NRC, the CPM V.3 and the CNCPS v.6 biology. The NRC biology is incorporated in Formulate 2 as well as in other software programs. Several companies use CPM V.3 and there are two commercial versions of the CNCPS v.6 biology: AMTS and NDS.

In the next Technical Series email, I will discuss the impact of these differences on the percentage of metabolizable lysine and methionine and how to interpret the results to maximize their utilization.

* Intake - 55 lbs of TMR per day

The Models Used to Formulate AA Balanced Rations

Basic knowledge of amino acid (AA) nutrition for lactating cows has significantly advanced in the last 50 years. However, only recently has that wisdom been harnessed into models that can be used on a day to day basis.

In the U.S., the three basic models currently used are NRC 2001, CNCPS and CPM. Over time, they have all evolved and changed to include improved equations that predict the cow’s responses with better accuracy. In 2001, NRC published its latest version, the last version of CPM (v.3) was released in 2003, and CNCPS released its latest version (v.6) in 2007. Each model has its own set of equations (i.e. “biology”) to predict the amino acid profile of the metabolizable protein (MP).

Each model also has its own methodology to evaluate the nutritional "quality" of the feed’s proteins. These differences have a direct impact on the predicted grams of MP and individual AAs the cow has available to fulfill her requirements.

The protein of any feed is partitioned into fractions A, B or C in the NRC model, or into fractions A, B1, B2, B3 and C in the CPM and CNCPS models:


Besides some differences in how these fractions are defined in each model, CPM and CNCPS have different degradation rates (Kd) for each fraction. In general, the Kds for the B1 and B2 fractions are lower for CNCPS v.6 versus CPM v.3. Hence, each model will provide a different prediction of MP supply and the AA profile of the MP.

In the next Technical mail we will discuss the impact of these differences and how we interpret each model’s output to optimize the AA utilization for maximal milk output.

Can Amino Acid Balancing of Dairy Rations Improve N-Utilization?

Feeding strategies to improve the utilization of the nitrogen (N) in a diet are important to reduce N excretion to the environment. Amino acid (AA) balancing presents the opportunity to do so, without negatively impacting milk performance. By concentrating the levels of the limiting amino acids methionine and lysine in the diet, less metabolizable protein (MP) and crude protein (CP) needs to be fed. This creates space in the ration to incorporate other beneficial feed ingredients:

A) Keep feed costs down by feeding less of expensive protein sources.
B) Enhance production by feeding more fermentable carbohydrate.

A trial with 70 cows was conducted at the University of Wisconsin with several objectives in mind; one of them was to improve the N efficiency by feeding an AA balanced ration. All cows were fed a diet containing 60% forage on a dry matter basis (58% corn silage - 42% alfalfa silage); the diet of one group of 15 cows was supplemented with ground shelled corn, high moisture shell corn, soybean meal, dried molasses, Energy Booster, a pre-mix with minerals and vitamins and 40 grams of dry MetaSmart®. Another group of 15 cows was fed a higher protein ration where corn distillers and Soyplus was also included in the formulation. The diet with MetaSmart was formulated according to NRC guidelines to provide:

A) A lower supply of MP (2450 grams vs. 2590 grams), reducing the CP concentration (15.7% vs. 16.8%) of the ration.
B) A higher NFC concentration (47.0% vs. 43.6%).

The cows fed MetaSmart produced 2 lbs extra milk with .08% extra fat and .14% extra protein, an increase of 3.5 extra lbs in Energy Corrected Milk (ECM). In addition, the cows fed MetaSmart had lower MUN, PUN and higher N efficiency.

a,b: Values with different superscript in the column are different (P < 0.05)

The results from this research show that by AA balancing rations using MetaSmart, MP supply can be reduced, improving N efficiency and still enhance ECM production.

¹Effect of feeding different sources of rumen-protected methionine on milk production and N-utilization in lactating dairy cows Chen et al., 2011 - J. Dairy Sci. 94:1978–1988

Is MetaSmart® better than Smartamine® M?

MetaSmart and Smartamine M are often compared to one another because they both supply methionine to the cow, but it is important to note that they are different products. MetaSmart is the isopropyl ester of HMB (methionine analog) and Smartamine M is based on a coated, true dl-methionine. The mode of action of the two products differs:

A) MetaSmart benefits rumen function and provides metabolizable methionine to the cow.
B) Smartamine M is solely a source of metabolizable methionine to the cow.

A trial with 70 cows was conducted at the University of Wisconsin with several objectives in mind. One of them was to compare (head-to-head) the impact each product would have on milk production and composition when fed to high-producing cows.¹

The cows were fed the same diet and either MetaSmart or Smartamine M was added to provide the estimated grams of required metabolizable methionine to maximize milk production and composition according to the NRC. This meant that 40 grams of dry MetaSmart or 15 grams of Smartamine M were added such that:

A) MetaSmart delivered 9 grams of HMB for ruminal use and 9 grams of HMB as a metabolizable methionine source to the cow.
B) Smartamine M delivered 9 grams of metabolizable methionine to the cow.

The cows fed MetaSmart produced 0.9 lbs. extra milk with .16% extra fat and .04% extra protein. To facilitate interpretation of those results, we recommend integrating these changes into a single number by calculating the Energy Corrected Milk (ECM). The cows fed MetaSmart produced 1.8 extra lbs of ECM; furthermore, they had lower Milk Urea Nitrogen than the cows fed Smartamine M.

a,b: Values with a different superscript are statistically different (P < 0.05)

The results from this research show that MetaSmart is just as good as Smartamine M as a metabolizable methionine source with the added benefit of improving rumen function.

¹Effect of feeding different sources of rumen-protected methionine on milk production and N-utilization in lactating dairy cows Chen et al., 2011 - J. Dairy Sci. 94:1978–1988