Associations among thermal biology, preovulatory follicle diameter, follicular and luteal vascularities, and sex steroid hormone concentrations during preovulatory and postovulatory periods in tropical beef cows

•High THI during the preovulatory and postovulatory periods caused an increase in the impairments of the ovarian POF and CL functions.•Effects of high THI on the impaired ovarian function are mainly based on the suppression of POF and CL vascularity, and the production of E2 and P4. 3.•There are neg...

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Bibliographic Details
Published in:Animal reproduction science 2020-02, Vol.213, p.106281-106281, Article 106281
Main Authors: Jitjumnong, Jakree, Moonmanee, Tossapol, Sudwan, Paiwan, Mektrirat, Raktham, Osathanunkul, Maslin, Navanukraw, Chainarong, Panatuk, Julakorn, Yama, Punnawut, Pirokad, Wilasinee, U-krit, Warittha, Chaikol, Warunya
Format: Article
Language:English
Subjects:
Heat stress
Ovarian function
Ovarian vascularity
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Summary:•High THI during the preovulatory and postovulatory periods caused an increase in the impairments of the ovarian POF and CL functions.•Effects of high THI on the impaired ovarian function are mainly based on the suppression of POF and CL vascularity, and the production of E2 and P4. 3.•There are negative effects associated with a THI that induces heat stress, such as impaired POF and CL function in tropical Bos indicus beef cows. The objectives were to evaluate effects of tropical seasons on thermal biology, preovulatory follicle (POF) diameter, POF and luteal vascularities, and estradiol (E2) and progesterone (P4) concentrations; and to determine the associations among the values for these variables during preovulatory and postovulatory periods in Thai native cows in tropical climates: cold, hot, and rainy seasons. Development and vascularity of the POF and corpora lutea (CL) were evaluated using color Doppler ultrasonography. The temperature-humidity index (THI) was greater when the preovulatory period occurred during the rainy season when compared with the occurrence during the hot and cold seasons of the year. Furthermore, POF diameter was less when the THI was greater. The THI was greater when the postovulatory period occurred during the rainy season when compared to the occurrence of the postovulatory period during the hot and cold seasons of the year. Furthermore, the CL vascularity and P4 concentration were less when the THI was greater. The THI was inversely correlated with CL vascularity and P4 concentrations. When the THI was greatest during the hot and rainy seasons of the year, there were the greatest negative effects on POF size, POF and CL blood flow, and concentrations of E2 and P4 during the preovulatory and postovulatory periods. While native Bos indicus are capable of adapting to tropical conditions, there are still negative effects, such as impaired POF and CL functions, when the THI induces heat stress.
ISSN:0378-4320
1873-2232
DOI:10.1016/j.anireprosci.2020.106281