NUTRITION ▶▶▶


Methionine – different forms, different bioavailability?


The essential amino acid methionine can be supplied to pig feed using different forms. Most recently, a new form, being feed grade L-methionine, has come onto the market. Recent research says its bioavailability is similar to DL-methionine, which is considered the standard up to now.


T


1000 1250 1500 1750 2000


250 500 750


0 L-Met ADFI, g/d ADG, g/kg Source: Yang and others (2019). 26 DL-Met gain:feed, g/g


BY DR ING JOHN HTOO, DIRECTOR TECHNICAL CONSULTANCY – SWINE, EVONIK NUTRITION & CARE, GERMANY


he amino acid methionine has a number of func- tions for pigs. Besides serving as an essential amino acid for optimum growth performance, methionine also plays an important role as a methyl donor for


DNA methylation and serves as a precursor for the synthesis of glutathione and taurine involved in antioxidant and immune functions in pigs. Methionine is available in different forms: • DL-Methionine (DL-Met; a 50:50 mixture of D- and L-iso- mers; 99% pure) – known as the ‘standard’ methionine source;


Figure 1 - Growth performance of young growing pigs fed diets supplemented with L‐Met or DL‐Met.


P > 0.50 1710 0.56 950 1750 0.55 960 0.60 0.40 Parameter 0.20 0.00


Myogenic differentiation 1 Myogenin


Myogenic factor 5 0.80


• Liquid methionine hydroxy analog-free acid (MHA-FA, 88% active substance);


• Calcium salt of hydroxy analog of methionine (MHA-Ca, 84% active substance), and


• L-Methionine (L-Met; 99% pure) which has recently be- come available on the market as a methionine source for balancing methionine levels in poultry and swine diets.


These methionine sources are available in the market at com- petitive prices. Compared with DL-MHA products, less research has been done to compare the relative bioavailability of L-Met compared with DL-Met in pigs. Bioavailability, in simple terms, indicates how much (in %) of a product is required to replace an- other similar product to achieve the same animal performance. The knowledge of actual availability of L-Met relative to DL- Met is critical for the economic optimal price difference, me- thionine specification in the least-cost feed formulation and to achieve optimal pig performance. Recent research has shed some light on the availability of L-Met vs. DL-Met in young pigs.


Effect on pig performance and myogenesis In 2019, researchers from the Mississippi State University, USA (Yang and others) evaluated the effects of methionine source


Table 1 – mRNA expression of se- lected myogenesis genes (longissi- mus dorsi) of pigs after feeding diets supplemented with L‐Met or DL‐Met for four weeks.


Treatment


L-Met DL-Met 1.03


1.08


Myocyte enhancer factor 2A 0.66 Myocyte enhancer factor 2C 2.39 Source: Yang and others (2019)


▶PIG PROGRESS | Volume 35, No. 6, 2019


1.12 0.9


P-value 0.79


1.22 1.05 0.66 1.25


1.69


0.48 0.27 0.55


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