Rumination Time and Physical Activity Monitoring, Milk Yield Changes Around Estrus and First Service Pregnancy Rate in Dairy Cows Assigned to Voluntary Waiting Period

YAZLIK, Murat Onur/0000-0002-0039-5597WOS: 000444016700003In high milk-yielding dairy cows, the energy balance challenges in early lactation and impact reproductive performance often affects estrus intensity, duration and detection. This study determined the role of a voluntary waiting period on rumination time, physical activity and milk yield changes during the peri-estrus period in the first service and further fertility in high-yielding dairy cows. To the best of our knowledge, this is the first study to demonstrate a relationship between voluntary waiting period and estrus-related parameters. This study was conducted on 145 Holstein-Friesian dairy cows aged 2 to 6 years of age. Cows were assigned a short voluntary waiting period, 45 to 70 day in milk (SVWP; n=73), and the long voluntary waiting period, 71 to 95 day in milk (LVWP; n=72). Rumination time, physical activity and milk yield changes around estrus in the first service were detected by an automated monitoring system. Artificial insemination procedures were performed between 45 to 70 days in milk for SVWP and 71 to 95 days in milk for LVWP. The barn's daily temperature and humidity index (THI) was recorded throughout the study period and was <72. Basal rumination time were significantly lower in SVWP (376.82 +/- 74.58 min/clay) than LVWP group at the day of estrus (352,07 +/- 68.90 min/day) (P<0.01). First service pregnancy rate was 23.72% and 38.46% in short and long voluntary waiting period, respectively (p