New research related to amino acid supplementation and 1) mitigating milk fat depression and 2) altering mammary extraction of nutrients
Abstract 1: APPLIED – AMINO ACID SUPPLEMENTATION AS A POTENTIAL STRATEGY TO MITIGATE MILK FAT DEPRESSION
Researchers at the University of Wisconsin – Madison also evaluated if they could help promote milk fat synthesis by supplying methionine and leucine during a milk fat depression that was induced by feeding dietary polyunsaturated fatty acids. Supplying methionine and leucine in the diet has been observed to increase milk fat synthesis via the mechanistic target of rapamycin complex 1 (mTORC1). Both methionine and leucine are essential amino acids (AA) that activate mTORC1.
The study was conducted as a replicated 4×4 Latin square. All diets included high starch. Factors were fat source: soybean oil or an 80% palmitate fat supplement; and AA level.
As expected, supplying soybean oil (linoleic acid) decreased milk fat percentage and yield compared to the control (palmitate fat supplement). While AA supplementation was not able to fully overcome the milk fat depression induced by soybean oil,it increased milk fat content and tended to increase milk fat production under both fat sources, partially mitigating the milk fat depression. The results further underscore the beneficial effects of AA supplementation on increasing milk fat production.
Abstract 2: APPLIED – ENERGY SOURCE AND AMINO ACIDS INDEPENDENTLY ALTER MAMMARY EXTRACTION OF NUTRIENTS
A separate study at the University of Wisconsin – Madison evaluated if mammary extraction of nutrients for the synthesis of milk components is affected by energy source (glucogenic or ketogenic) and by balanced AA supplementation. Twenty dairy cows were enrolled in a replicated 4×4 Latin square with four 28-d periods and 4 treatments arranged as a 2×2 factorial. Factors were AA level, AA deficient, or AA sufficient, balanced for methionine, lysine, and leucine (branched chain AA); and energy source: glucogenic or ketogenic.
Overall, energy source did not affect mammary extraction of nutrients, except for fatty acids (FA) that were supplied at a higher level by the ketogenic diet. On the other hand, balanced AA supplementation increased mammary extraction of AA and FA, in line with the observed response in milk protein and fat production by that treatment. The observed results underscore the benefits of AA balancing on mammary uptake of essential AA, which can support the activation of mTORC1 and, thereby, milk component synthesis. mTORC1 is a cellular nutrient sensing complex that regulates metabolic processes like protein and fat synthesis.
AA balancing dairy cow rations has been observed to enhance both milk protein and fat synthesis. Additionally, insulin and glucogenic energy have been observed to stimulate milk protein yields in dairy cows. Both insulin and AA, particularly methionine and leucine, stimulate mTORC1.
Features: Kathryn Ruh, Ph.D. student at Arriola Apelo Lab, University of Wisconsin-Madison, USA.