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Optimize the amino acid profile

To think about a change in digestible amino acid (AA) recommendations of dairy cows, knowledge is lacking to optimize the AA profile according to energy level. The efficiency of protein utilization (total quantity of AA) is dependent on energy supply: protein synthesis is an energy intensive metabolic synthesis. Bringing a good AA profile promotes the synthesis of milk proteins and increases the efficiency of nitrogen utilization. However, the total amount of AA catabolized depends on the available energy (level and nature). The optimal balance between the contribution of the 4 essentials amino acids which are the most limiting (methionine, histidine, lysine and leucine) and the energy supply is not known.

Liver and mammary metabolisms

These AA are catabolized in two different organs (the liver for methionine and histidine and the mammary gland for lysine and leucine), the aim will be to study the liver and mammary metabolisms of these AA at different energy supplies and to investigate the consequences for milk components (protein, fat and lactose). This work will focus on the increase of the nitrogen efficiency of dairy cows and decrease of the urea releases. A well-balanced intake of Digestible Amino Acids in the Intestine (AADI) is one of three feeding strategies that reduces nitrogen supply while maintaining a good export of AA in milk proteins (Lemosquet et al., 2014, Haque et al., 2012 and 2015) and thereby reduces the excretion of urinary urea nitrogen from AA catabolism.

Recommandations on methionine, histidine, lysine et leucine

This work will also contribute to the production of knowledge needed to improve the AADI recommendations of dairy cows. As a follow-up to the work carried out in the Systali project (program for the revision of ruminant feeding systems by Inra), the knowledge provided will allow us to reflect on the expression of AADI in dairy cows, in particular to see if an expression according to energy level is judicious, as expressed in the growing pig (INRAPorc) and in the American system for dairy cows of the Cornell Net Carbohydrate and Protein System (Van Amburg et al., 2015).

Cléo Omphalius is working on this subject of thesis since the 1st november of 2016 for 3 years. She is supervised by Sophie Lemosquet in the team alimentation and nutrition.

Bibliography

• Lemosquet, S., M. N. Haque, P. Faverdin, J.-L. Peyraud, and L. Delaby. 2014. A bas comme à hauts niveaux d'apports PDI, corriger le profil en acides aminés digestibles dans l'intestin permet d'augmenter les matières protéiques du lait et l'efficience d'utilisation des PDI chez la vache laitière. Renc. Rech. Ruminants. 21:139–142. [lien]
• Haque, M.N., Guinard-Flament, J., Lamberton, P., Mustière, C. and Lemosquet, S., 2015. Changes in mammary metabolism in response to the provision of an ideal amino acid profile at 2 levels of metabolizable protein supply in dairy cows: consequences on efficiency. Journal of Dairy Science 98: 3951-3968. [DOI]
• Haque, M.N., Rulquin, H., Andrade, A., Faverdin, P., Peyraud, J.L. and Lemosquet, S., 2012. Milk protein synthesis in response to the provision of an "ideal" amino acid profile at 2 levels of metabolizable protein supplies in dairy cows. Journal of Dairy Science 95: 5876-5887. [DOI]
• Van Amburgh, M. E., Collao-Saenz , E., Higgs, R., Ross, D., Recktenwald, E., Raffrenato, E., Chase, L. E., Overton, T. R., Mills, J., & Foskolos, A. (2015). The Cornell Net Carbohydrate and Protein System: Updates to the model and evaluation of version 6.5. Journal of Dairy Science. 98:6361-6380. [DOI]

Contact

Cléo Omphalius cleo.omphalius[at]inra.fr