Low Doses of Bovine Somatotropin Enhance Conceptus Development and Fertility in Lactating Dairy Cows1

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.

Regulation of an Opioid Receptor Chaperone Protein, RTP4, by Morphine

“…In addition to serving as a chaperone protein for the transport of GPCRs (Behrens et al, 2006;Décaillot et al, 2008;Gifford et al, 2008), RTP4 has been shown to have other physiologic roles. RTP4 is one of the interferon-stimulated genes increased in peripheral blood leukocytes after pregnancy and, thus, could be used as a marker of pregnancy, particularly in rodents (Gifford et al, 2008;Ribeiro et al, 2014;Kose et al, 2016;Sinedino et al, 2017). In addition, RTP4 plays an important role as a marker of disease incidence in conditions such as hypertension in type 2 diabetic patients, Q-fever, interferon-induced depression, HER2(1) breast cancer, and virus infection (Laurin et al, 2013;Mehraj et al, 2013;Davenport et al, 2015;Hoyo-Becerra et al, 2015;Radkowski et al, 2016).…”

Embryo Mortality Around the Period of Maintenance of the Corpus Luteum Causes Alterations to the Ovarian Function of Lactating Dairy Cows

“…Ribosomal protein L19 (RPL19) was used as a reference gene and ΔCt's, ΔΔCt's and fold changes for ISG15 and MX2 were calculated as described in Livak and Schmittgen [31] using each cow's day 14 as reference. The reference gene was chosen based on the absence of effects of treatments on the abundance of its mRNA and similar cDNA amplification efficiencies between target genes and the reference gene calculated here and elsewhere [32].…”

Effects of heat stress on ovarian functions and embryonic development: mechanism and potential strategies to alleviate these effects in dairy cows

“…Both somatotropin and IGF-I receptors are expressed in ovarian follicles and immature oocytes (Longergan et al 2000). Under thermoneutral conditions, low doses (325 mg) of bST during the pre-and peri-implantation periods (days 0 and 14 post insemination) reduced embryonic losses and improved fertility (Ribeiro et al 2013). Exposure of dairy cows to heat stress decreased plasma IGF-I concentration in association with reduced oocyte quality (de Rensis & Scaramuzzi 2003).…”