Friday, January 11, 2013

Research Findings from the 2012 JAM Conference - Part 3

Research has shown cows fed methionine enriched diets produce more milk with better milk composition. Methionine is an essential amino acid that also plays other important metabolic functions. Immediately after calving the cow experiences a negative energy balance due to a relative low dry matter intake versus nutrient demands for high milk production. Body reserves are mobilized leading to potential excessive fat accumulation in the liver. Methionine is essential for the synthesis of Apoprotein B and for the synthesis of Phosphatidyl Choline, both necessary for the formation of very low density lipoproteins (VLDLs) required for ensuring transport of the fat away from the liver (Durand, 1992). It has also been shown in other species that methionine metabolism also plays a key role in decreasing oxidative stress.

Results from a research trial to show the impact of feeding a methionine enriched diet on the oxidative stress and immune status of cows during transition were presented at the ADSA in July 2012 (Osorio, 2012). The underlying hypothesis was that methionine would improve liver function and reduce oxidative stress and inflammation.

Three groups of cows were fed the same basal diet from 21 days before the expected calving day until 28 days after parturition. MetaSmart® or Smartamine® M were added to the basal diet to achieve a LYS:MET ratio of 2.8:1. The cows fed either, MetaSmart® or Smartamine® M, had greater albumin concentration an indicator a good liver function. Those same cows also had lower blood concentrations of Haptoglobin, Ceruplasmin, Serum Amyloid A and Interleukin-6, indicating a reduced inflammatory response. Furthermore, those cows had a better antioxidant status indicated by a higher oxygen radical absorbance capacity and glutathione concentration.The authors concluded that the cows fed the methionine enriched diets had a lower systemic inflammatory state, an enhanced liver function and a greater antioxidant capability.

Methionine is thus a key nutrient in transition cow nutrition, not only as a building block for protein synthesis but as a key intermediate to enhance the metabolic processes. This can lead to better liver function, oxidative and inflammatory status, thus allowing the dairy cow to withstand the challenges of the transition phase of lactation.

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