Low doses of bovine somatotropin enhance conceptus development and fertility in lactating dairy cows

Biol Reprod. 2014 Jan 16;90(1):10. doi: 10.1095/biolreprod.113.114694. Print 2014 Jan.

Abstract

Objectives were to evaluate the effects of administering either one or two low doses of slow-release recombinant bovine somatotropin (bST) on hormone concentrations, conceptus development, and fertility in dairy cows. Cows from two farms were detected in estrus on or after 50 days postpartum (n = 1483), inseminated, and enrolled in the study (Day 0). Within farm, cows were blocked by parity and assigned randomly to receive a single placebo injection at insemination (control), a single injection with 325 mg of bST at insemination (S-bST), or two injections with 325 mg of bST administered on Days 0 and 14 (T-bST). From a subset of cows, blood was collected twice weekly from Day 0 to 42 for determination of hormone concentrations and on Day 19 for isolation of leucocytes and analysis of transcript abundance of selected interferon-stimulated genes. Pregnancy was diagnosed on Days 31 and 66, and ultrasonographic morphometry of the conceptus was performed on Days 34 and 48 in a subset of cows. Cows that received T-bST had increased plasma concentrations of GH and IGF1 for 4 wk, increased mRNA expression of ISG15 and RTP4 in leukocytes, earlier rise in the pregnancy-specific protein B in plasma of pregnant cows, increased conceptus size, and enhanced fertility. Cows that received S-bST had increased concentrations of GH and IGF1 for only 2 wk and it was insufficient to alter conceptus development and fertility. In conclusion, supplementation with low doses of bST during the pre- and peri-implantation periods enhanced conceptus development, reduced embryonic losses, and improved fertility in dairy cows.

Keywords: bST; conceptus; dairy cow; fertility.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle* / embryology
  • Cattle* / physiology
  • Dairying
  • Dose-Response Relationship, Drug
  • Embryonic Development / drug effects*
  • Estrus Synchronization
  • Female
  • Fertility / drug effects*
  • Growth Hormone / administration & dosage*
  • Insemination, Artificial / veterinary
  • Lactation
  • Pregnancy
  • Pregnancy Rate

Substances

  • Growth Hormone