Thank you for attending our webinar “Importance of Methionine as a feed additive and its economic relevance” on June 14. We had so many questions that our experts weren't able to answer them all on the day. However, they were all important to us, so we're following up with a full list of answers to each question asked during the event.

Question: Please clarify difference between DL Methionine, L-Meth and other variants. Which one is more bioavailable?

Answer: While the question on relative bioavailability for methionine hydroxy analogue relative to DL-Methionine was addressed in the webinar and is recommended to be 65% on weight to weight basis, L-Methionine was not addressed. However, applying the same methodology would reveal no differences between L- and DL-Met which means same bioavailability.
There are also products in which methionine or the hydroxy analogue of methionine act as ligand for e.g. trace minerals. The same findings reported in the webinar, which means 65% bioavailability for methionine hydroxy analog relative to DL-methionine, apply to these methionine-trace mineral products
Other products are on the market claiming methionine activity (such as herbal Met) although they do not contain any methionine. Our research clearly suggests that those cannot act as methionine source nor they may allow sparing of methionine except dietary methionine is well above requirement – however, in this latter case methionine can just be reduced.
Finally, also producers of methyl group donators and respective feed additives, such as choline and betaine, often claim that a certain portion of supplemental methionine can be replaced and/or spared by these products. There are a couple of publications as well showing that this is not possible –, only if methionine supply is per se above requirement. Again, just finetuning Met and Met+Cys specifications would reveal the savings without another additive.

Question: Does the recommended bioefficacy of 65% also apply for the energy values of the methionine hydroxy analogue products?

Answer: This was addressed already during Q&A in the webinar. Of course, the bioefficacy need to be reflected in the energy value. Anything else would not be in line with the relative bioavailability approach which is actually comparing products with all their nutritional aspects and not just methionine. Falling into the trap of giving methionine hydroxy analogue a relative higher energy value than methionine would avoid realizing full economic benefit.

Question: Do your recommendations regarding methionine : lysine ratios even apply in diets using high levels of raw materials with high protease inhibitor contents eg field beans versus diets with only hipro soya as the sole protein supplying ingredient?

Answer: Our recommendations are based on standardized ileal digestible amino acids. Digestibility coefficients were generated in various institutions with various ingredient samples. However, those investigations would include impacts on proteases. Indeed, a digestibility is still an estimate and variations are possible. Also, for beans or peas some maximum levels are recommended and maximum use at 20% is often advised to consider generally ANF.
In addition, e.g. trypsin inhibitors are deactivated by heat treatment and while for field beans the activity is not as high as for other legumes, conditions during pelleting may help deactivating already. With respect to soybean products (field beans not yet) Evonik offers an NIR service to detect under- (relevant for protease inhibition) and over-processing (heat-damage) which is called AMINORed®. This service would also give an indication how to adjust digestibile amino acid levels of the ingredients in case of deviations from standard quality.

Question: Can I give methionine via drinking water to chicken instead of mix with feed?

Answer: Application of amino acids via drinking water is a matter of solubility as well as of the risk to provoke biofilm. In the latter context it is not only one but the sum of all products offered via drinking water. Indeed, for some special applications it might be an option, e.g. Met plays a role in immune response and if there is a challenge, metabolism and immunology can be supported by extra nutrients.
Solubility of DL-Met is approximately 30 g/L at 20 °C.

Question: Why did DLM65 do so well when used at 3g/kg!?

Answer: When requirement is met, no further improvement can be expected. Even with a diluted product maximum performance can be achieved. This is the principle of next limiting nutrient (factor) and would be visualized by the Liebig-Barrel.
The important question is not why DLM65 was allowing for maximum performance at highest inclusion level, but what is the minimum dose of DLM65 to achieve maximum  performance in comparison to minimum dose of pure DL-Methionine (MetAMINO®) or methionine hydroxy analogue. Indeed, you will find out according to the webinar and Lemme et al. (2020, animals) that only 65% as much MetAMINO® would be needed compared to both DLM65 and methionine hydroxy analogue (on weight to weight basis).

Question: What do you think about a case of low bioavailabilty of DL-Methionine from the raw materials (e.g from soya bean meal).  Can we stick to the 65%.

Answer: As pointed out in the webinar. The recommended 65% bioavailability of methionine hydroxy analogue relative to DL-methionine is a universally applicable number. This means also, the recommendation works under any nutritional condition and is independent on feed ingredient choice and quality and can, thus, be applied.
Of course, soybean meal would only contain L-Methionine but if there is no processing damage, standardized ileal digestibility of methionine in soybean products is usually high (about 90%) – however, digestibility of cysteine is somewhat smaller resulting in a Met+Cys digestibility of about 85%.

Question: Methionine is not allowed to be used in organic feed in some countries. What is the reason? Is the use of Hydrox-Analog allowed (because it is not an amino acid)?"

Answer: Particularly according to the European legislation supplemental amino acids, particularly methionine products, are not allowed in organic feed. The rationale behind is probably that those are not natural. All amino acids are covered.
This applies also methionine hydroxy analogue as it belongs to the category “amino acids, their salts and analogues”. In addition, organic acids are also not permitted.

Question: What do you think about mix use half and half of Metamino and MHA?

Answer: In principle this can be done as long as the relative bioavailability of 65% for MHA products is considered. Otherwise  economic benefit cannot fully be realized and/or there is a risk that animal performance may suffer.
We know that this concept is sometimes applied especially in chicken starter feed. The reason for not 100% use of MHA-products is an uncertainty of mixing quality as dosing of the liquid and viscous MHA-FA bears a higher risk for heterogenous distribution as well as adherence of the product to the equipment with contaminations of later batches. This we observe in our AMINOBatch® and AMINOBatch Working Precision Test services where both accuracy and precision of supplementation is evaluated.
Accurate and homogenous supply of methionine sources plays a particular role in starter chicken as their feed consumption is small and these small portions should contain all nutrients and energy the chicken needs. If this is not the case, there is a short-term imbalance in nutrient intakes which would result in reduced uniformity of the flock. Adherence to the equipment might even result in undersupplementation with risk of not meeting requirements. Producers thus want to reduce the risk by mixing both products 1:1 and thus utilizing the ideal mixing properties of DL-Methionine.

Question: When we use products as guanaminoacetic acid, carnitine, Betaine, Choline, etc, could theoreticaly decrease the methionine requirements?

Answer: The requirement is property of the animal and may depend on hygiene (e.g. extra nutrient needs for immune response). Other factors may not necessarily change the requirement but optimal dietary dose, e.g. if a reduced dietary energy level decreases increases feed consumption, other nutrient levels should be adjusted in order to balance ideal nutrient intake (see concept of AMINOChick® 3.0).
As explained earlier, some additive producer claim sparing effects. In terms of methionine sparing herbal methionine, choline and betaine are prominent examples. Research clearly confirms that all of them cannot spare methionine unless Met supplementation exceeds requirements. However, in this latter case just reducing methionine supplementation would have the same effect.
With respect to guanaminoacetic acid, the story is different as with addition to the diet, the animals do not need to synthesise this compound itself and, thus, would not need the respective precursors. Therefore, guanamino acetic acid spares arginine and glycine.

Question: Is there a nutritional limit of methionine use in commercial diets?

Answer: Yes! Nutritionists aim to balance all nutrients in the commercial diets according to the requirements of the target animal. If any nutrient does not meet this requirement it is limiting the performance. If a nutrient such as an amino acid (methionine) is well in excess to the requirement, it provokes an imbalance. The typical reaction of farm animals is reducing feed intake as self-defense mechanism against intoxication. In severe cases, they would refuse the feed. While there is a certain level for tolerating high levels, levels affecting feed intake would latest define the “nutritional” limit.
However, if nutrients are well balanced, there is no further limit for methionine supplementation.