Positive relationship of rectal temperature at fixed timed artificial insemination on pregnancy outcomes in beef cattle.

Autor:	Liles HL; Department of Animal Science, Institute of Agriculture, University of Tennessee, Knoxville, TN 37996, USA., Schneider LG; Department of Animal Science, Institute of Agriculture, 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., Oliveira Filho RV; Department of Animal Science, Pregnancy and Developmental Programming Area of Excellence, Texas A & M University, College Station, TX 77843, USA., Neal Schrick F; Department of Animal Science, Institute of Agriculture, University of Tennessee, Knoxville, TN 37996, USA., Payton RR; Department of Animal Science, Institute of Agriculture, University of Tennessee, Knoxville, TN 37996, USA., Rhinehart JD; Department of Animal Science, Institute of Agriculture, University of Tennessee, Knoxville, TN 37996, USA., Thompson KW; University of Tennessee Institute of Agriculture, Middle Tennessee Research and Education Center, Spring Hill, TN 37174, USA., McLean K; Department of Animal Science, Institute of Agriculture, University of Tennessee, Knoxville, TN 37996, USA., Edwards JL; Department of Animal Science, Institute of Agriculture, University of Tennessee, Knoxville, TN 37996, USA.
Jazyk:	angličtina
Zdroj:	Journal of animal science [J Anim Sci] 2022 Jul 01; Vol. 100 (7).
DOI:	10.1093/jas/skac100
Abstrakt:	The overarching aim was to examine the relationship of rectal temperature at fixed time artificial insemination (FTAI) on pregnancy outcomes in a typical breeding season with expected pregnancy rates approaching 50% using Bos indicus and Bos taurus cattle. This represents a continuum of steps to test the hypothesis that elevated body temperature at or around insemination is functionally important to maximize pregnancy outcomes. Rectal temperature of Bos indicus cattle at FTAI ranged from 37.0 to 40.9 °C; 60.6% were hyperthermic. Positive factors impacting pregnancy outcomes were rectal temperature at FTAI, body condition, and estrus patch scores. Rectal temperature at FTAI was positively associated with pregnancy outcomes (P < 0.0001); per each 1 °C increase pregnancy odds increased 1.9 times (95% CI: 1.4 to 2.6). Highest pregnancy outcomes occurred with rectal temperatures exceeding 40 °C (P = 0.0004). Rectal temperature before FTAI in Bos taurus cattle ranged from 37.8 to 41.8 °C; 43.3% were hyperthermic. Factors impacting pregnancy were rectal temperature at FTAI, estrus activity, parity, and ambient conditions on day of FTAI. Rectal temperature of Bos taurus cattle at FTAI was positively associated with pregnancy (P = 0.0286); odds increased 1.45 times (95% CI: 1.0 to 2.0) per each 1 °C increase. Highest pregnancy outcomes occurred with rectal temperatures at FTAI exceeding 40 °C (P = 0.057). Moreover, positive relationship of rectal temperature at FTAI to pregnancy persisted in estrual females (71.25% of total; P = 0.0408; OR 1.5; 95% CI: 1.0 to 2.2). Mindful that 1) elevated temperatures observed in Bos indicus and Bos taurus cattle directly promote meiotic resumption of the oocyte in vitro and that 2) in vivo hyperthermia alters intrafollicular components which others have shown to potentiate ovulation and promote meiotic resumption, it is biologically plausible that an acute elevation in body temperature at or around time of insemination is functionally important to maximize pregnancy outcomes. (© 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
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