Triennial lactation symposium

Mammary metabolism of amino acids in dairy cows

H. Lapierre*, G. E. Lobley, L. Doepel, G. Raggio, H. Rulquin, S. Lemosquet

*Corresponding author for this work

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

Although in dairy cows the mammary gland (MG) is the major net user of essential AA (EAA) supply, milk protein synthesis from absorbed EAA is not a straightforward process. Early studies identified 2 groups of EAA based on different pattern of mammary utilization: group 1 [Met, Phe (+Tyr), Trp], where MG uptake was similar to secretion in milk protein, and group 2 (Arg, Ile, Leu, Lys, Thr, and Val), where uptake exceeded milk protein output. This review examines the validity of this classification under variable protein supply through a meta-analysis, with the outcomes then explained with studies in which the fates of individual EAA were monitored using isotope approaches. For the meta-analysis, the Fick principle, based on stoichiometric transfer of Phe+Tyr uptake to milk protein, was used to estimate mammary plasma flow across all studies. This approach was judged acceptable because doubling Phe supply did not result in mammary oxidation of Phe+Tyr and either limited or no contribution of peptides to Phe and Tyr mammary supply could be detected. The AA content of proteins synthesized by the MG was estimated from milk protein composition, and the uptake-to-output ratio (U:O) for individual AA was re-calculated based on these assumptions. Analysis of individual samples by isotopic dilution resulted in reduced variance compared with analysis on pooled samples performed with an AA analyzer. Globally, the U: O of His and Met is maintained close to unity under variable protein supply. The group 2 AA could be subdivided. First, the U: O for group "2v" AA (Ile, Leu, Val, and Lys) is greater than 1 and varied with protein supply. Accordingly, the increased U: O of Leu, induced by duodenal casein infusion, led to extra-mammary Leu oxidation. Decreasing Lys supply decreased Lys U: O and the associated transfer of N to non-EAA, mainly to Glx, Asx, Ser, and Ala. Second, the U: O of group "2nv" AA, Arg and Thr, does not vary with protein supply. The Arg U: O averages 2.5, whereas the Thr U: O, albeit averaging 1.2, does not differ from unity. Excess of both these AA is probably directed toward the synthesis of non-EAA rather than energy supply. Overall, the ability of the MG to use excess EAA-N supply offers alternative sources of N and C for energy provision, lactose synthesis and non-EAA synthesis. The latter function spares dietary non-EAA for other necessary processes, such as gluconeogenesis and energy supply, in other tissues to support lactation.

Original languageEnglish
Pages (from-to)1708-1721
Number of pages14
JournalJournal of Animal Science
Volume90
Issue number5
Early online date1 May 2012
DOIs
Publication statusPublished - May 2012

Keywords

  • amino acid
  • dairy cow
  • mammary
  • protein
  • MILK PROTEIN-SYNTHESIS
  • DRAINED VISCERAL FLUX
  • PERFUSED GOAT UDDER
  • FED GRASS-SILAGE
  • SPLANCHNIC METABOLISM
  • ABOMASAL INFUSION
  • NITROGEN-UTILIZATION
  • HEPATIC-METABOLISM
  • SODIUM CASEINATE
  • HOLSTEIN COWS

Cite this

Lapierre, H., Lobley, G. E., Doepel, L., Raggio, G., Rulquin, H., & Lemosquet, S. (2012). Triennial lactation symposium: Mammary metabolism of amino acids in dairy cows. Journal of Animal Science, 90(5), 1708-1721. https://doi.org/10.2527/jas.2011-4645

Triennial lactation symposium : Mammary metabolism of amino acids in dairy cows. / Lapierre, H.; Lobley, G. E.; Doepel, L.; Raggio, G.; Rulquin, H.; Lemosquet, S.

In: Journal of Animal Science, Vol. 90, No. 5, 05.2012, p. 1708-1721.

Research output: Contribution to journalArticle

Lapierre, H, Lobley, GE, Doepel, L, Raggio, G, Rulquin, H & Lemosquet, S 2012, 'Triennial lactation symposium: Mammary metabolism of amino acids in dairy cows', Journal of Animal Science, vol. 90, no. 5, pp. 1708-1721. https://doi.org/10.2527/jas.2011-4645
Lapierre H, Lobley GE, Doepel L, Raggio G, Rulquin H, Lemosquet S. Triennial lactation symposium: Mammary metabolism of amino acids in dairy cows. Journal of Animal Science. 2012 May;90(5):1708-1721. https://doi.org/10.2527/jas.2011-4645
Lapierre, H. ; Lobley, G. E. ; Doepel, L. ; Raggio, G. ; Rulquin, H. ; Lemosquet, S. / Triennial lactation symposium : Mammary metabolism of amino acids in dairy cows. In: Journal of Animal Science. 2012 ; Vol. 90, No. 5. pp. 1708-1721.
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T2 - Mammary metabolism of amino acids in dairy cows

AU - Lapierre, H.

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AU - Raggio, G.

AU - Rulquin, H.

AU - Lemosquet, S.

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KW - amino acid

KW - dairy cow

KW - mammary

KW - protein

KW - MILK PROTEIN-SYNTHESIS

KW - DRAINED VISCERAL FLUX

KW - PERFUSED GOAT UDDER

KW - FED GRASS-SILAGE

KW - SPLANCHNIC METABOLISM

KW - ABOMASAL INFUSION

KW - NITROGEN-UTILIZATION

KW - HEPATIC-METABOLISM

KW - SODIUM CASEINATE

KW - HOLSTEIN COWS

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DO - 10.2527/jas.2011-4645

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VL - 90

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EP - 1721

JO - Journal of Animal Science

JF - Journal of Animal Science

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ER -