Short Communication: Influence of estrus activity and reproductive tract size and position scores on fertility in Bos indicus and Bos taurus suckled beef cows.

Autor:	Speckhart SL; Department of Animal Science, University of Tennessee, Knoxville, TN 37996, USA., Oliveira Filho RV; Department of Animal Science, Pregnancy and Developmental Programming Area of Excellence, Texas A&M University, College Station, TX 77843, USA., Franco GA; Department of Animal Science, Pregnancy and Developmental Programming Area of Excellence, Texas A&M University, College Station, TX 77843, USA., Vasconcelos JLM; Department of Animal Production, São Paulo State University, Botucatu, SP, Brazil., Schrick FN; Department of Animal Science, University of Tennessee, Knoxville, TN 37996, USA., Edwards JL; Department of Animal Science, University of Tennessee, Knoxville, TN 37996, USA., Pohler KG; Department of Animal Science, Pregnancy and Developmental Programming Area of Excellence, Texas A&M University, College Station, TX 77843, USA.
Jazyk:	angličtina
Zdroj:	Journal of animal science [J Anim Sci] 2022 Jun 01; Vol. 100 (6).
DOI:	10.1093/jas/skac141
Abstrakt:	The primary objective of this study was to determine if estrus activity and reproductive tract size and position score (SPS) are associated with pregnancy outcomes in Bos indicus (Nelore) and Bos taurus (Angus) beef cows. In study 1, multiparous Nelore cows (n = 1,280) were artificially inseminated at a fixed time (FTAI, day 0) using an estradiol and progesterone (P4)-based estrus synchronization protocol. In study 2, multiparous Angus cows (n = 764) were artificially inseminated at a fixed time (FTAI, day 0) using a gonadotropin-releasing hormone and P4-based estrus synchronization protocol. Estrus activity was assessed using Estrotect heat detector patches and scored on day 0 using the following scoring system: 0 (patch was lost, most likely due to repeated mounting), 1 (<25% activation), 2 (≥25%, <50% activation), 3 (≥50%, <75% activation), or 4 (>75% activation) where patch scores of 1 and 2 signified no or limited estrus activity, whereas scores of 0, 3, and 4 had increased estrus activity. Reproductive tract SPS were assigned on day 0 as SPS1: small and compact resting within the pelvic cavity; SPS2: intermediate, resting partially outside the pelvic cavity; and SPS3: larger and resting outside the pelvic cavity. Pregnancy diagnosis was performed by ultrasound on day 30 and 100 after FTAI. Cows were determined as undergoing pregnancy loss if a viable embryo with heartbeat was detected at day 30 but was no longer present at day 100. Pregnancy rate at day 30 was influenced by estrus activity and SPS in both Nelore (P = 0.004) and Angus (P = 0.009) cows. Specifically, cows with smaller reproductive tracts (SPS1) had greater (P < 0.001) pregnancy rate when estrus was expressed before FTAI. There was no effect of estrus activity nor reproductive tract size on pregnancy loss between day 30 and 100 for both breeds. In summary, estrus activity before FTAI may influence reproductive outcomes differently depending on size and position of the reproductive tract at time of breeding. (© The Author(s) 2022. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu