Promoting effects of an extended photoperiod treatment on the condition of hair coats and gonadal function in Thoroughbred weanlings

Takehiro HARADA; Yasuo NAMBO; Mutsuki ISHIMARU; Fumio SATO; Kentaro NAGAOKA; Gen WATANABE; Kazuyoshi TAYA

doi:10.1294/jes.26.147

Note

Promoting effects of an extended photoperiod treatment on the condition of hair coats and gonadal function in Thoroughbred weanlings

Takehiro HARADA, Yasuo NAMBO, Mutsuki ISHIMARU, Fumio SATO, Kentaro NAGAOKA, Gen WATANABE, Kazuyoshi TAYA

Author information

Takehiro HARADA
United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan
Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
Yasuo NAMBO
United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan
Department of Clinical Veterinary Science, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido 080-8555, Japan
Mutsuki ISHIMARU
Hidaka Training and Research Center, Japan Racing Association, Hokkaido 057-0171, Japan
Fumio SATO
United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan
Hidaka Training and Research Center, Japan Racing Association, Hokkaido 057-0171, Japan
Kentaro NAGAOKA
United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan
Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
Gen WATANABE
United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan
Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
Kazuyoshi TAYA
Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
Shadai Corporation, Hokkaido 059-1432, Japan

Keywords: extended photoperiod treatment, gonadal function, molting of winter coat, progesterone, Thoroughbred weanling

JOURNAL FREE ACCESS

2015 Volume 26 Issue 4 Pages 147-150

DOI https://doi.org/10.1294/jes.26.147

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Abstract

The effects of an extended photoperiod (EP) treatment (14.5 hr light, 9.5 hr dark) on Thoroughbred colts and fillies from December 25 at 7–9 months old to the following May at 12–14 months old on coat condition and gonadal functions were investigated. Coat condition was evaluated in April. The colts and fillies in the EP treatment group changed from winter to summer coats (molting of winter coats), whereas those in the control group did not. To determine the day of first ovulation, the plasma concentrations of progesterone were measured once a month in fillies. The day of first ovulation was advanced in the EP treatment fillies compared with the control fillies. The present study clearly demonstrated that the EP treatment advanced the molting of winter coats and advanced ovulation in fillies, even in weanlings.

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