Reproductive responses of lactating dairy cows according to estrus behavior and CIDR uses in a heatsynch protocol

ABSTRACT

Background: The timed artificial insemination (TAI) protocols have been used worldwide as a first service artificial insemination (AI) breed system as well as to resynchronize cows diagnosed as not pregnant. The benefits associated to Heatsynch are the lower cost of the protocol and the increase in the number of cows detected in estrus. Furthermore, it has been suggested that protocols combining AI after estrus detection followed by TAI could increase overall conception rates, as well as increased AI submission rates. The aim of this study was evaluate reproductive responses of dairy cows submitted to a Heatsynch protocol according the estrus behavior and controlled internal device release (CIDR) uses.Material, Methods & Results: Holstein lactating cows (n = 562) were enrolled in protocol using (CIDR) (1.9 g of progesterone) insertion at (day 0) D0 either a new one, a previous used once (7 days - second use) or twice used (14 days - third use). Based on the detection of estrus and the moment of AI after the CIDR removal, cows were divided into 3 groups cows showing signs of estrus and therefore AI 36 to 60 h after CIDR removal (EPTAI group; n = 241); cows showing estrus and AI 72 h after CIDR removal (ETAI group; n = 207); and cows that did not show any sign of estrus after CIDR removal and were TAI 72 h later (NoETAI group; n = 335). Previous to the first postpartum...(AU)