Alternative low doses and routes of administering a prostaglandin F2α analogue to induce luteolysis in Nelore cows

Abstract

The present study was conducted in order to verify the efficacy of lower doses and alternative routes of a prostaglandin F2α analogue, luprostiol (PGF), for the induction of luteolysis and the precipitation of estrus in nonlactating Nelore cows (Bos taurus indicus). A conventional dose (15 mg) of PGF was compared to doses lower than the conventional dose, which ranges from 10 to 50%, that were administered intramuscularly (IM), intravulvosubmucosally (IVSM), or in the Bai-hui acupuncture site located within the lumbosacral area. The cows were administered PGF 8 day after estrus in the presence of a corpus luteum, and randomly assigned to the following groups: G1 (positive control), 15 mg, IM (n = 23); G2, 7.5 mg, IM (n = 23); G3, 3.75 mg, IM (n = 24); G4, 7.5 mg, IVSM (n = 25); G5, 3.75 mg, Bai-hui acupoint (n = 24); and G6, 1.5 mg, Bai-hui acupoint (n = 25). The results indicated that 50% of a conventional dose of PGF (7.5 mg) resulted in a complete luteal regression (plasma progesterone <1 ng/ml) at Hour 48, and hastened estrus, regardless of whether or not PGF was administered IM or IVSM. Comparatively, 10 or 25% of the conventional dose, even when administered to the Bai-hui acupoint, resulted in an initial reduction in the concentration of progesterone at Hour 24, followed by an increase observed at Hour 48. In conclusion, 25% of a conventional PGF dose administered via the Bai-hui acupoint proved inadequate to induce a complete luteal regression, whereas 50% of a conventional dose administered IM or IVSM was found to be the minimal dose required to induce effectively a complete luteal regression, and to precipitate the onset of estrus in nonlactating Nelore cows.

Effect of two low doses of prostaglandin F2α on luteolysis in dairy cows

“…Similar results were reported by Brusveen et al (2009) and Giordano et al (2013), which demonstrated the failure of luteolysis in dairy cows following the single dose of PGF 2α in the Ovsynch protocol (Brusveen et al, 2009;Giordano et al, 2013). A half dose of PGF 2α would induce 30.4% of the cows with partial luteolysis (Meira et al, 2006). Based on the results of consecutive monitoring of the serum P4 concentrations and CL sizes from day 0 to 4 in all experimental cows, we suggested that the second treatment of PGF 2α was needed to persistently enhance the regression of CL.…”

Dosage and routes of administration of prostaglandin: Practical implications for the reproduction of cows, mares and pigs

“…Mimo różnic w długości okresu półtrwania nie stwierdzono różnic w odsetku krów, u których dochodziło do pełnej luteolizy po podaniu kloprostenolu lub dinoprostu. Zaznaczała się natomiast tendencja do poprawy wyników zacieleń po podaniu kloprostenolu, zarówno po inseminacji w pierwszej (40% wobec 35%), jak i drugiej (23% do 21%) rui (24,30). Podając 25 mg prostaglandyny dwukrotnie w odstępie 8 godzin ruję przejawiało więcej krów niż przy podaniu jednokrotnym.…”

“…Interesujące obserwacje dotyczą możliwości obniżania dawki prostaglandyny bez zmniejszania jej właściwości luteolitycznych. Podając (30).…”

Probability of pregnancy and risk factors of the Ovsynch program and its modification in dairy cows – a review

“…This resulted in higher conception rates than in the classical Ovsynch protocol (Carvalho et al 2015a;b). An increase in the proportion of cows with visible signs of oestrus and with completed luteolysis, as well as a higher rate of conceptions can be obtained by choosing a different way of prostaglandin application and different doses (Meira et al 2006;Liu et al 2017). The pregnancy rate was 57.2% after ischiorectal fossa (IRF) injection of conventional dinoprost dose whereas the intramuscular injection resulted in 52.6% pregnancies (Holland 2015).…”