In this scenario, nutritionists have two main options: reduce the cost of feed, mainly achievable through the modification of kind and quantity of raw materials used; or optimize the feed cost, by enhancing the nutritional properties of the raw materials and supplementing eventual deficient nutrients through the use of specific feed additives. Thus, optimizing feed formulas means to define the most cost-effective ration while matching specific targets, as for instance, the animal performances and/or improving the impact of feed production on environment.

Nutritionists have the complex mission to optimize efficiency of animal feed within a restricted feed cost acceptable range. Raw materials suppling energy and protein represent the main fractions in complete feeds. Good knowledge of their effective nutritional values as well as the use of any feed additive that can enhance and/or complete their nutritional values will result in an effective feed cost optimization. Moreover, despite some differences, this is true independently of their feed formulas are developed for integrated group or commercial feed mills.

Methionine sources, as key additives to optimize feed cost

Various additives are available on the market that would help nutritionist to optimize their feed formulas. A key role is played by the amino acids, and among them by the available sources of methionine in both powder (DL-Methionine, L-Methionine and OH-Methionine salts) or liquid form (OH-Methionine). As first, it let them to match the requirement of this limiting amino acid without overdosing protein sources, that normally results in an excess of other amino acids then wasted by the animals. This will surely have an impact on the feed cost, as well as on environment since all other amino acids in excess when excreted increase the nitrogen pollution.

Between the various sources of methionine, identify the most appropriate one will allow the best cost savings. Reports from various scientific papers as well as recent metanalysis demonstrate the bioequivalence between the various methionine form, when applied at equimolar basis. As consequence the inclusion in poultry feed of one methionine source compared to others will primarily follow the application cost criteria. Notoriously the OH-Methionine form is available on the market at more efficient price.

Importance of applying updated formulation matrix value for methionine sources

Beside their main function to supply methionine to match animal requirements, methionine sources own other proven nutritional features, normally listed in their product matrix. This is true also for the OH-Methionine (OH-Met) form, such as Rhodimet® AT88, for which we strongly suggest nutritionist to apply its most updated matrix. This will help them to further optimize feed cost without impacting animal performances. Moreover, formulating applying the correct matrix of Rhodimet® AT88 will allow to reach the specific targets for all players involved in livestock business: commercial feed miller, integrated group and farmers.

Feed miller will have high flexibility in raw material selection with consequent feed cost reduction, allowing them to successfully act in this very competitive market. The integrator will register a positive impact of the optimized diets on animal performances, thus a clear improvement of their main economical target: reduction of cost per kg of animal origin product (meat or eggs). Finally, farmers will benefit from buying feed at lower cost without compromising animal performances.

Further optimizations can be achieved applying the validated matrix of the various sources of methionine, in particular for their protein and energy values.

Use of a Crude Protein value for OH-Methionine in formulation

In feed industry we tend to refer to the term of crude protein (CP) as reference of the protein content of each diet. Crude proteins principle is also used as reference for qualitative/quantitative feed analysis, and it is calculated multiplying the total nitrogen level of a diet by the constant factor 6.25. This last one was determined considering an average nitrogen content in protein fractions (16%). Despite its wide use, the principle of crude protein is criticized by newly research approaches due to various limitations it owns. As first, not all nitrogen sources are proteins. Secondly not all protein sources have the same nitrogen content and thus must have a different constant factor for converting them to protein level. For instance, for most of grains and soybean, the most appropriate factor must be 5.7-5.8 rather than 6.25. Last but not the least, if we apply the same principle to amino acids, we will have some of them having a low CP value as well as other showing a CP level significantly higher than 100%.

A specific case is represented by the OH-methionine, that, while from a nutritional point of view its efficacy equivalence with the DL-Methionine (DL-Met) is scientifically proven, could not have a CP level due to the absence of a nitrogen group. It is obvious that, formulating with OH-Met to match the methionine requirements, without assigning any CP level, will negatively impact the feed formula optimization. This is because the system will compensate its CP level by extra inclusion of protein sources, notoriously high-cost raw materials. Adisseo recommend applying the equivalent CP level of 51.7% for Rhodimet® AT88, calculated considering the 88% of CP level of the DL-Met form.

Use of recommended energy value for OH-Methionine in formulation

A specific analysis must be done while evaluating both Metabolizable (ME) or Net Energy (NE) of the various methionine sources. To assign the energy value of any product, we start with determination of Gross Energy (GE), the intrinsic energy that turns in heat, commonly determined via the calorimetric bomb. Moreover, considering the complete digestibility of crystalline amino acids, their Digestible Energy (DE) is 100% and then equal to the GE. Fixed these, we can then calculate the ME deducting from the GE/DE the fraction lost via the urine.

But why different methionine sources have variable ME-NE level? It is well known that all methionine sources are used by animals after being metabolized in the L-Methionine (L-Met) form, however each of them will have their specific metabolic pathways. Since OH-Methionine has a different metabolic pathway rather than L-Met/DL-Met, this will result in a different ME and NE level.

The detailed metabolic pathways and consequent determination of ME and NE levels were explained in a recent published paper (Van Milgen et al. 2019). We can simplify it mentioning that the OH-Methionine has a NH₂sparing effect, recycling an amino group derived from other amino acid in excess. This will prevent the excretion of these amino groups in excess under uric acid that lead to energy savings. To make it simple, all molecules (i.e L-Met, DL-Met or OH-Met) present the same carbon chain and hence the same intrinsic energy but in case of OH-Met, this value is enriched by the savings from excess amino groups that are recycled.

Feed formulation practical case in broiler:

Characteristics:

14 to 25 day old broilers
Metabolizable Energy: 3 050 kcal/kg
Crude protein: 21.2%
dLys: 1.15% & dMet+Cys: 0.87%

In formulation, we use the energy values of methionine sources, obtained as explained before:

Metabolizable energy for DL-Methionine – poultry: 5 391 kcal/kg
Metabolizable energy for OH-Methionine – poultry: 5 384 kcal/kg

	Cost (€/ton of product)	DL-Methionine Recommended energy values		Rhodimet® AT88 Recommended energy values
	Cost (€/ton of product)	Inclusion (%)	Cost (€/ton of feed)	Inclusion	Cost (€/ton of feed)
Wheat	333	35.00	116.55	35.00	116.55
Soybean meal 48	580	30.61	177.51	30.61	177.53
Corn	346	28.10	97.21	28.07	97.12
Rapeseed oil	1450	3.00	43.49	2.99	43.29
Monocalcium phosphate	1250	0.83	10.37	0.83	10.37
Calcium carbonate	57	0.82	0.47	0.82	0.47
Broiler premix	5000	0.50	25.00	0.50	25.00
DL-Methionine	2550	0.285	7.26
Rhodimet® AT88	2244			0.320	7.19
Sodium bicarbonate	550	0.27	1.46	0.27	1.46
L-Lysine HCl 98%	1900	0.26	4.85	0.26	4.85
L-Threonine	1900	0.13	2.55	0.13	2.55
Rov Max Advance	20000	0.01	1.00	0.01	1.00
Feed cost (€/ton)			487.92		487.58

Prices November 2022

Using recommended energy values of methionine sources in formulation reduces the feed cost of the OH-Met based diet more importantly than the DL-Met based diet. In the example, there is a saving of 0.34 euro per ton of feed for feed supplemented with Rhodimet® AT88 vs DL-Methionine.

Conclusion

Applying the appropriate methionine nutritional matrix will result in a feed cost optimization, by optimizing complete feed CP and ME-NE. Because of its nutritional values and relative cost, OH-Methionine form is the best option while formulating optimal diets, especially when its validated matrix is completely applied.

References:

J. van Milgen, D.I. Batonon-Alavo, Y. Mercier, R. Ferrer, A. Toscana, R. Martin-Venegas. The cost of the conversion of L-methionine precursors in mammals and birds. 2019, EAAP Scientific Series: 138 – Pages: 365 – 366 https://doi.org/10.3920/978-90-8686-891-9_108

Product names and availability may vary by region, please contact your local Adisseo representative for more information.