Nutritional modulation of the somatotropin/insulin-like growth factor system: Response to feed deprivation in lactating cows

M. A. McGuire, D. E. Bauman, D. A. Dwyer, W. S. Cohick

Research output: Contribution to journalArticlepeer-review

105 Scopus citations

Abstract

Mid-lactation Holstein cows (n = 4) were used to evaluate the effects of complete feed deprivation on circulating insulin-like growth factors (IGF) and their binding proteins (IGFBP). Comparisons were made between cows in fed and unfed conditions and included response to a single injection of bovine somatotropin (bST). Two days of feed deprivation decreased milk yield 66%. Concentrations of bST nearly doubled during feed deprivation, whereas glucose and insulin steadily decreased. Circulating concentrations of IGF-I decreased nearly 50%, IGF-II decreased 28% and IGFBP-2 increased 49% during the 2 d of feed deprivation. In contrast, IGFBP-3 was not affected. Eighteen to 24 h after the bST challenge, circulating concentrations of IGF-I rose 100% during the fed period, but there was no response during the unfed period. Blood concentrations of IGF-II decreased 17% after bST challenge in the fed period but were unchanged in the unfed period. More moderate undernutrition (80% of requirements) did not affect circulating IGFBP-2 but did alter the response of IGFBP-2 to bST. A conceptual model was developed that illustrates that nutritional regulation of the ST/IGF system represents a key component signaling the appropriate use of nutrients. Overall, results demonstrate that nutritional modulation of the ST/IGF system plays a key role in animal performance and well-being over a wide range of physiological situations.

Original languageEnglish (US)
Pages (from-to)493-502
Number of pages10
JournalJournal of Nutrition
Volume125
Issue number3
StatePublished - 1995
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

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