Effects of Increased Ambient Temperature During IVM and/or IVF on the In Vitro Development of Bovine Zygotes

Sugiyama, Sadahiro, McGowan, Michael, Phillips, Nancy, Kafi, Majataba, & Young, Mary (2007) Effects of Increased Ambient Temperature During IVM and/or IVF on the In Vitro Development of Bovine Zygotes. Reproduction in Domestic Animals, 42(3), pp. 271-274.

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Previous research by this group (2003) has demonstrated that heat stress during in vitro culture (IVC) significantly increased early embryo mortality. The experiments reported here examine the effects of heat treatment (HT) during in vitro maturation (IVM) and during in vitro fertilization (IVF). One 24 h cycle of HT entailed a series of 0.5°C incubator temperature increases from 39°C to 39.5°C for 2 h, to 40°C for 2 h, to 40.5°C for 4 h, 41°C for 4 h, 40.5°C for 6 h and 40°C for 6 h. This cycle mimics rectal temperatures recorded in high producing, grain fed dairy cows in hot climates. Experiment I studied the effects of one cycle of heat-treatment during IVF on the rate of cleavage of in vitro matured presumptive zygotes. Total cleavage rate in the HT group (37.8%) was lower than that of the control group (54.6%, p < 0.05). Experiment II repeated the HT of experiment I but preceded it with a cycle of HT during IVM. The total cleavage rates for control and heat treatment groups were 75.5% and 37.9%, respectively, with a significant difference of p < 0.001 identified. Experiment III examined the rates of embryonic development to ≥8-cell stage (after 72 h IVC) and to morula or blastocyst (M/B) stage (after 144 h IVC) following HT of the oocyte groups during the preceding IVM or IVF. Rates of development to ≥8-cell stage (at 72 h IVC) and to M/B stage (after 144 h IVC) for the control group were 27.5% and 35.8%. Those of IVM-only HT and IVF-only HT groups were 13.8% and 14.6%, and 8.6% and 14.3%, respectively. Both groups of heat treated embryos developed at significantly lower rates (p < 0.05) than did the control group. These results suggest that hyperthermia during oocyte maturation and/or fertilization adversely affects oocyte maturation and fertilization rates and retards further embryonic development.

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ID Code: 14761
Item Type: Journal Article
Refereed: Yes
DOI: 10.1111/j.1439-0531.2006.00776.x
ISSN: 0936-6768
Subjects: Australian and New Zealand Standard Research Classification > AGRICULTURAL AND VETERINARY SCIENCES (070000) > ANIMAL PRODUCTION (070200) > Animal Reproduction (070206)
Divisions: Past > QUT Faculties & Divisions > Faculty of Built Environment and Engineering
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2007 Blackwell Publishing
Copyright Statement: Reproduced in accordance with the copyright policy of the publisher.
Deposited On: 09 Sep 2008 00:00
Last Modified: 29 Feb 2012 13:31

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