The effect of Equilume light masks on the timing of seasonal ovulation of Thoroughbred mares in South Korea

Abstract

Advancing the estrous cycle of mares is an essential breeding strategy that is routinely conducted by Thoroughbred breeders to improve economic outcomes. For this purpose, Equilume light masks have been developed as an alternative to existing technologies such as artificial lighting or hormonal treatments because they are considered as valid as existing methods with additional animal welfare advantages. For example, with the Equilume light masks, horses can be let out into the pasture, whereas they have to be kept indoors during lighting treatment. Because the function of Equilume light mask on the estrous cycle of mares is influenced by environmental factors such as nutrition condition and temperature, Equilume light mask should be studied in various environments. The objective of the present study was thus to verify the effect of Equilume light masks on the onset of the estrous cycle in Thoroughbred mares in South Korea. Mares were randomly selected and separated into two groups at two Thoroughbred horse breeding farms. The mares in the treatment group were equipped with Equilume light masks from November 18 to February 10 the following year. The body condition, the number and size (> 35 mm) of uterine follicles, and the uterine horn score of the mares were assessed on January 6 and February 10. The body condition scores were not different between the two groups. The treatment with the Equilume light mask had no positive effects on developing follicles and the reproductive tract. In conclusion, the use of Equilume light masks did not influence the seasonal resumption of the estrus cycles in Thoroughbred mares in South Korea.

Efficiency of Equilume light mask on the resumption of early estrous cyclicity and ovulation in Thoroughbred mares

“…However, our study findings were different from the previous assessment of the effect of the Equilume light masks on hastening the reproductive cycle parameters of mares [ 25 ]. Results of the reproductive examinations conducted in February showed that several mares exposed to blue light treatment exhibited estrus cycles and ovulation in Jeju Island, whereas none of the mares previously examined at this time exhibited ovarian activity when maintained at locations inland in Korea [ 25 ]. The BCS for the mares were not significantly different from that of the previous research, but the temperature was significantly different [ 29 ].…”

“…However, unpublished data collected by an experienced veterinarian involved in this study and who has worked within the Thoroughbred breeding industry on Jeju Island for more than twenty years suggests that the mean date of first ovulation in unlit mares occurs between late March and early April. A similar experimental design to the current study was employed previously to evaluate light therapies at advancing seasonal reproductive activity in mares However, our study findings were different from the previous assessment of the effect of the Equilume light masks on hastening the reproductive cycle parameters of mares (25). Results of the reproductive examinations conducted in February showed that several mares exposed to blue light treatment exhibited estrus cycles and ovulation in Jeju Island, whereas none of the mares previously examined at this time exhibited ovarian activity when maintained at locations inland in Korea (25).…”

“…A similar experimental design to the current study was employed previously to evaluate light therapies at advancing seasonal reproductive activity in mares However, our study findings were different from the previous assessment of the effect of the Equilume light masks on hastening the reproductive cycle parameters of mares (25). Results of the reproductive examinations conducted in February showed that several mares exposed to blue light treatment exhibited estrus cycles and ovulation in Jeju Island, whereas none of the mares previously examined at this time exhibited ovarian activity when maintained at locations inland in Korea (25). The BCS for the mares were not significantly different from that of the previous research, but the temperature was significantly different (29).…”

“…To meet the industry requirements for early breeding, we previously conducted a study to evaluate the effectiveness of Equilume light masks in advancing seasonal reproductive activity of mares on the mainland of Korea. However, the induction of early reproductive activity in Thoroughbred mares was not observed on February 10 in this study [ 25 ]. During the study, Korea experienced very cold weather, wherein the minimum temperature was −12.8°C and mares had infrequent access to pasture grazing.…”

Classification of behavioral signs of the mares for prediction of the pre-foaling period

“…36, No. 2, June 2021 100 mone, seasonal effect to reproductive organ, device for controlling seasonal effect and biotechnology for embryo transfer (Park et al, 2017;Yu et al, 2017;Lee et al, 2020;Seong et al, 2020). Especially, the foaling is considered as one of main topics among several fields of reproductive physiology of mares.…”