Protein metabolism in lactating goats subjected to the insulin clamp

B J Bequette, C E Kyle, L A Crompton, Susan E. Anderson, M D Hanigan

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

A model of Leu and protein metabolism by the mammary gland and hind leg of lactating goats was constructed and evaluated from data collected by using [N-15, 1-C-13]Leu kinetics measured during amino acid (AA) infusion and a hyperinsulinemic-euglycemic clamp (IC). Goats were given continuous intravenous infusions of either saline or AA (65 g/d) for 7.5 d and from d 5 to 7.5 goats were subjected to IC. Arteriovenous kinetics were monitored on d 4 and 8 by continuous infusion (8 h) of [N-15, 1-C-13]Leu. Milk protein yield was increased by IC (+10%) and IC + AA (+21%), whereas AA infusion had no effect. The data were used to construct model equations that describe rates of protein synthesis and degradation, and from these equations, milk and muscle net protein synthesis were described. The model was unable to describe the observed responses in milk protein synthesis. Similar to observations in the literature, net protein gain by the hind leg increased with AA, IC, and IC + AA infusion, primarily through stimulation of protein synthesis by AA. For both tissues, IC depressed Leu oxidation, but only in the absence of AA infusion. Although the IC appears to regulate the ability of the mammary gland to coordinate blood flow and Leu catabolism in support of protein synthesis, our ability to construct a precise model describing mammary protein anabolism is still limited. In contrast, the response in protein anabolism of the hind-leg tissues of these midlactation goats was predicted well by the model, which indicate that the leg tissues were more sensitive to AA supply than the mammary gland.

Original languageEnglish
Pages (from-to)1546-1555
Number of pages10
JournalJournal of Dairy Science
Volume85
Issue number6
DOIs
Publication statusPublished - Jun 2002

Keywords

  • insulin
  • protein synthesis
  • amino acid metabolism
  • milk protein
  • MAMMARY-GLAND
  • AMINO-ACID
  • SKELETAL-MUSCLE
  • DAIRY-COWS
  • LEUCINE METABOLISM
  • FASTED LAMBS
  • DRY GOATS
  • PHENYLALANINE
  • INFUSION
  • HINDLIMB

Cite this

Bequette, B. J., Kyle, C. E., Crompton, L. A., Anderson, S. E., & Hanigan, M. D. (2002). Protein metabolism in lactating goats subjected to the insulin clamp. Journal of Dairy Science, 85(6), 1546-1555. https://doi.org/10.3168/jds.S0022-0302(02)74224-0

Protein metabolism in lactating goats subjected to the insulin clamp. / Bequette, B J ; Kyle, C E ; Crompton, L A ; Anderson, Susan E.; Hanigan, M D .

In: Journal of Dairy Science, Vol. 85, No. 6, 06.2002, p. 1546-1555.

Research output: Contribution to journalArticle

Bequette, BJ, Kyle, CE, Crompton, LA, Anderson, SE & Hanigan, MD 2002, 'Protein metabolism in lactating goats subjected to the insulin clamp', Journal of Dairy Science, vol. 85, no. 6, pp. 1546-1555. https://doi.org/10.3168/jds.S0022-0302(02)74224-0
Bequette, B J ; Kyle, C E ; Crompton, L A ; Anderson, Susan E. ; Hanigan, M D . / Protein metabolism in lactating goats subjected to the insulin clamp. In: Journal of Dairy Science. 2002 ; Vol. 85, No. 6. pp. 1546-1555.
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AU - Kyle, C E

AU - Crompton, L A

AU - Anderson, Susan E.

AU - Hanigan, M D

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N2 - A model of Leu and protein metabolism by the mammary gland and hind leg of lactating goats was constructed and evaluated from data collected by using [N-15, 1-C-13]Leu kinetics measured during amino acid (AA) infusion and a hyperinsulinemic-euglycemic clamp (IC). Goats were given continuous intravenous infusions of either saline or AA (65 g/d) for 7.5 d and from d 5 to 7.5 goats were subjected to IC. Arteriovenous kinetics were monitored on d 4 and 8 by continuous infusion (8 h) of [N-15, 1-C-13]Leu. Milk protein yield was increased by IC (+10%) and IC + AA (+21%), whereas AA infusion had no effect. The data were used to construct model equations that describe rates of protein synthesis and degradation, and from these equations, milk and muscle net protein synthesis were described. The model was unable to describe the observed responses in milk protein synthesis. Similar to observations in the literature, net protein gain by the hind leg increased with AA, IC, and IC + AA infusion, primarily through stimulation of protein synthesis by AA. For both tissues, IC depressed Leu oxidation, but only in the absence of AA infusion. Although the IC appears to regulate the ability of the mammary gland to coordinate blood flow and Leu catabolism in support of protein synthesis, our ability to construct a precise model describing mammary protein anabolism is still limited. In contrast, the response in protein anabolism of the hind-leg tissues of these midlactation goats was predicted well by the model, which indicate that the leg tissues were more sensitive to AA supply than the mammary gland.

AB - A model of Leu and protein metabolism by the mammary gland and hind leg of lactating goats was constructed and evaluated from data collected by using [N-15, 1-C-13]Leu kinetics measured during amino acid (AA) infusion and a hyperinsulinemic-euglycemic clamp (IC). Goats were given continuous intravenous infusions of either saline or AA (65 g/d) for 7.5 d and from d 5 to 7.5 goats were subjected to IC. Arteriovenous kinetics were monitored on d 4 and 8 by continuous infusion (8 h) of [N-15, 1-C-13]Leu. Milk protein yield was increased by IC (+10%) and IC + AA (+21%), whereas AA infusion had no effect. The data were used to construct model equations that describe rates of protein synthesis and degradation, and from these equations, milk and muscle net protein synthesis were described. The model was unable to describe the observed responses in milk protein synthesis. Similar to observations in the literature, net protein gain by the hind leg increased with AA, IC, and IC + AA infusion, primarily through stimulation of protein synthesis by AA. For both tissues, IC depressed Leu oxidation, but only in the absence of AA infusion. Although the IC appears to regulate the ability of the mammary gland to coordinate blood flow and Leu catabolism in support of protein synthesis, our ability to construct a precise model describing mammary protein anabolism is still limited. In contrast, the response in protein anabolism of the hind-leg tissues of these midlactation goats was predicted well by the model, which indicate that the leg tissues were more sensitive to AA supply than the mammary gland.

KW - insulin

KW - protein synthesis

KW - amino acid metabolism

KW - milk protein

KW - MAMMARY-GLAND

KW - AMINO-ACID

KW - SKELETAL-MUSCLE

KW - DAIRY-COWS

KW - LEUCINE METABOLISM

KW - FASTED LAMBS

KW - DRY GOATS

KW - PHENYLALANINE

KW - INFUSION

KW - HINDLIMB

U2 - 10.3168/jds.S0022-0302(02)74224-0

DO - 10.3168/jds.S0022-0302(02)74224-0

M3 - Article

VL - 85

SP - 1546

EP - 1555

JO - Journal of Dairy Science

JF - Journal of Dairy Science

SN - 0022-0302

IS - 6

ER -