Comparison in Effect of Heatsynch with Heat Detection Aids and CIDR-Heatsynch in Dairy Heifers

摘要

The objective of the present study was to determine whetherudoestrous detection with the help of oestrous detection aidsudduring the Heatsynch without timed AI protocol is equallyudeffective with the progesterone-combined protocol in dairyudheifers. A total of 148 heifers were randomly assigned to one ofudthe two groups. A group of heifers treated with Heatsynchudwith heat detection aids (n = 72) received GnRH on day 0,udprostaglandin F2a (PGF2a) on day 7 and oestradiol benzoateud(EB) on day 8, while in controlled internal drug releaseud(CIDR)-Heatsynch group (n = 76), CIDR was includedudduring a period from GnRH to PGF2a. Heifers were checkedudfor oestrus twice daily, i.e. from 09:00 to 10:00 hours and fromud15:00 to 16:00 hours starting on day 2 for Heatsynch groupudand on day 8 in CIDR-Heatsynch group, and continued up toudday 12. KAMAR heat mount detector (KAMAR Inc.,udSteamboat Springs, CO, USA) and ALL-WEATHER udPAINTSTIK (LA-CO Industries Inc., Elk Grove Village,udIL, USA) were used as heat detection aids. AI was conductedudwithin 1 h after confirming oestrus in 72 heifers, while 19udanimals were transferred with embryo 7 days after oestrusudaccording to the request of the owners. Premature oestrusudbefore PGF2a injection occurred in 18% of Heatsynch group.udOf 13 heifers which showed premature oestrus, six wereudinseminated and two of them conceived. Oestrus detection rateudwithin 12 days after initiation of the protocols did not differudbetween the two groups (94% vs 95%). There was nouddifference in the conception rate after first AI (includingudheifers that were inseminated before PGF2a injection) andudembryo transfer between Heatsynch with heat detection aidsudand CIDR-Heatsynch groups (36% vs 44% and 70% vs 56%).udIt is concluded that the use of heat detection aids to monitorudthe occurrence of premature oestrus prior to PGF2a injectionudin Heatsynch protocol in dairy heifers was equally effective toudthe inclusion of CIDR.