Pre-ovulatory follicular temperature in bi-ovular cows

Abstract

In a previous study on monovular cows, follicles revealed a mean antral (follicular fluid) temperature 1.54°C cooler than rectal temperatures in ovulating cows, whereas no such temperature differences were detected in non-ovulating cows. The present study adds to our previous work, this time considering 24 bi-ovular cows (one follicle per ovary). In order to increase the number of pre-ovulatory follicles failing to ovulate, this study was performed under heat-stress conditions. Follicular temperatures of the ovulating follicles (n = 31) were 0.93°C significantly cooler (P < 0.0001) than rectal temperatures, whereas no significant differences in temperature were found in non-ovulating follicles (n = 17). Eight cows became pregnant. The results of the present study indicate that, similar to those in monovular cows, pre-ovulatory follicles in bi-ovular cows were cooler than deep rectal temperatures and those temperature gradients were not found in follicles showing ovulation failure.

Effects of melatonin on production of reactive oxygen species and developmental competence of bovine oocytes exposed to heat shock and oxidative stress duringin vitromaturation

“…As stated in the previous paragraph, the oocyte is more resistant to disruption by heat shock than the early cleavage-stage embryo. Moreover, there is recent evidence in the cow that intrafollicular temperature of the ovulatory follicle is about 0.9 to 1.1°C lower than rectal temperature (López-Gatius & Hunter, 2019a, b). Thus, the actual degree of heat shock at the level of the oocyte may be less than the temperature used here.…”

Establishment of long-term chronic recording technique of <i>in vivo</i> ovarian parenchymal temperature in Japanese Black cows

“…In previous studies, body temperature, ovarian temperature, and uterine and vaginal temperatures have been associated with fertility success, especially ovulation efficiency. The mean follicular fluid temperature in preovulatory follicles was lower than the temperatures of both the uterine surface and rectum in ovulating cows, whereas no such difference in temperature was detected in non-ovulating cows [7][8][9].…”

Evolutionary sequences in mammalian reproductive biology

“…As noted in a range of domestic species-rabbit, sheep, pig, and cow-and also in women, the difference in temperature between the preovulatory follicle and neighboring tissues extends from 0.1°C to 2.5°C or more (Hunter, 2012;Hunter, Einer-Jensen, & Greve, 2006;Hunter, Grøndahl, Greve, & Schmidt, 1997;Hunter & López-Gatius, 2020). A follicle that is 1.0°C or more cooler than adjacent tissues is a frequent finding, overwhelming evidence coming most recently from cow ovaries (López-Gatius & Hunter, 2017, 2019a, 2019b.…”