Methionine is much more than milk protein
Protected methionine can be a valid tool to improve health and performance. This article provides an overview on the metabolic roles of this amino acid, when it can be profi table to use it, and what you can expect from it.
BY DAIRY CONSULTANT LUIS CARDO, DVM, AND DR CLAUDIA PARYS,TECHNICAL SERVICE MANAGER RUMINANTS, EVONIK
C mLys (% MP) 7.00 6.77 Source: Van Amburgh, 2015 20 ▶ COW HEALTH | AUGUST 2020
ows do not have a requirement for Crude Protein (CP) or Rumen Undegradable Protein (RUP, bypass). The rumen uses Non Protein Nitrogen (NPN) to synthesise high-quality microbial protein that will
supply the largest part of the Metabolizable Protein (MP). High-producing cows have a higher need of amino acids arriving at the intestine than their rumen can provide. Covering this extra requirement by supplying more CP results in increasing supplies of both Rumen Degradable and Undegradable Protein and comes with high environmental, economic and health cost. Studies show it is possible to achieve the same, or higher, milk yield with lower CP by using a nutritional strategy based on a combination of maximising production of microbial protein coupled with the use of protected amino acids to cover the needs for amino acids. This approach comes along with lower feed costs and higher Income Over Feed Cost. The two first limiting amino acids for milk production are methionine and lysine, due to their low concentrations in feed protein and high concentration in
Table 1 – Optimum AA concentrations in MP (%) in CNCPS v6.5 (NDS/AMTS).
mMet (% MP) Max. Milk Protein Yield 2.60
Max. Milk Protein Content 2.85
Optimal Lys/Met 2.70 2.40
Methionine has a big focus in dairy cow research because of its important metabolic roles.
milk. Methionine has a big focus in dairy cow research because of its important metabolic roles. These extra benefits in terms of cow health can be even more important than the direct effect on milk production or milk protein yield.
Methionine: A functional amino acid Research shows methionine fed pre-fresh and post-fresh affected post-calving metabolism through increased liver functionality, neutrophil function and insulin, while decreas- ing oxidative stress, inflammation and circulating Non Esteri- fied Fatty Acids (NEFAs). This is likely explained through an in- crease of taurine and glutathione in the liver, what causes a reduction of oxidative stress and, therefore, cytokines. De- creased cytokine levels lead to lower satiety signals which leads to higher feed intake. Reproduction is also affected by methionine supplementation. Cardoso (WDMC, 2017) commu- nicated a reduction of pregnancy losses from 28 to 61 days af- ter artificial insemination from 19.6% to 6.1% on multiparous cows when top-dressing protected methionine on a basal diet with 6.9% mLys and 1.87% mMet in MP. Recommendations have been published and updated in the past, with a trend for higher methionine concentrations in MP (Table 1). When there is more demand for energy than for amino acids, the liver diverts amino acids towards energy supply. For example, the foetus depends on amino acids for up to 50% of its glucose, and so does the periparturient cow. It makes sense to correlate amino acid requirements to energy, and indeed, the latest recommendations follow this pattern. 1. Target 1.12-1.15 g mMet/Mcal ME 2. Keep Lys/Met ratio at 2.7
PHOTO: CARSTENPAUL
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