Impacts of anticipating ovulation resynchronization by early detection of non-pregnant dairy cows with doppler ultrasound

• Grant number: 20/05878-8
• Support type: Scholarships in Brazil - Master
• Effective date (Start): May 01, 2020
• Effective date (End): November 30, 2021
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal researcher: Guilherme Pugliesi
• Grantee: Adomar Laurindo Neto
• Home Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 15/10606-9 - Innovations in the early pregnancy diagnosis in cattle, AP.JP

Abstract

Our objective in the present study will be to perform the early detection of non-pregnant dairy cows with the advent of Doppler Ultrasonography, and thus evaluate the efficiency of a super-early resynchronization protocol for ovulation of cows detected as non-pregnant in order to reduce the interval between inseminations and consequently reduce the interval between births, generating a better reproductive efficiency of the herd. 400 Holstein females will be used, with 45 to 55 days postpartum. The animals will be submitted to a protocol of estrus synchronization and ovulation for time IA, as already performed on the property. On D17 after the 1st IATF, the animals will be divided into 2 experimental groups: Control Group (beginning of Resynchronization on Day 31); n = 200) and super-early Ressinc Group (beginning of Resynchronization on Day 17; n = 200). At D24, the early diagnosis of pregnancy will be performed based on the detection of luteolysis by Doppler ultrasound only in females of the Super-early Ressinc group. At this time, the animals will be classified as pregnant and non-pregnant according to the functionality of the corpus luteum (luteal blood perfusion). The non-pregnant females will continue the synchronization protocol with the application of a dose of PGF2± and on the 26th the progesterone implant (P4) will be removed and the application of 1 mg of estradiol cypionate (CE) and 300 IU of chorionic gonadotropin equine (eCG). 48 hours after the removal of the P4 device, the females will receive the 2nd IATF on the 28th. At D31, the diagnosis of the 1st time IA gestation in all animals will be carried out and the animals in the Control group will be resynchronized. On Day 59 and 73 the pregnancy diagnosis of the 2nd time IA will be made in the Ressinc and Controle groups. Both will be performed by mode B transrectal ultrasound due to the presence of a viable embryo (heartbeat). It is expected with the present experiment to perform the early identification of non-pregnant dairy cows by the technique of detecting luteolysis through Doppler ultrasound, reducing the calving interval from conception in dairy cows that fail to become pregnant after the first IATF and so optimizing the reproductive, productive and economic efficiency of the system. (AU)