21 RELATIONSHIP BETWEEN DURATION OF ESTRUS BEHAVIOR DETERMINED BY RADIOTELEMETORY SYSTEM AND THREE FACTORS (MILK PRODUCTION, STEROID HORMONE, AND OVULATION TIME) IN DAIRY COWS

Abstract

Many studies have reported on the low fertility of dairy herds during the past several years. The object of this study was to investigate the relationships between duration of estrus and various factors (milk production, peripheral steroid hormones, and period from estrus to ovulation). All primiparous and multiparous Holstein cows (n = 62) were fitted pedometers (Gyuho; Comtec, Miyazaki, Japan) that measure total counts of walking activity per hour and send the individual cow