Early pregnancy diagnose by evaluation of corpus luteum function in Bos indicus beef cattle

• Grant number: 13/03082-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2013
• End date: January 31, 2014
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Guilherme Pugliesi
• Grantee: Yasmin Nabuco de Paiva
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 11/03226-4 - Signatures of receptivity, AP.TEM

Abstract

The maternal recognition of pregnancy between days 15 and 19 post-ovulation is involved in one of the main biological challenges to reach high fertility rates in cattle. However, the pregnancy diagnosis method most used in beef farms is through the transrectal ultrasonography between days 28 and 40 post-artificial inseminations (AI), which does not allow the identification of non-pregnant cows before the following estrous and ovulation (about day 21-postovulation). Therefore, diagnosis methods that detect non-pregnant animals earlier are needed to reduce the interval of inseminations. Thus, this study aimed: (1) identify functional characteristics of corpus luteum in pregnant, non-pregnant, and cows with embryo death during early gestation phases in Bos Indicus beef cattle; and (2) determinate the accuracy of detection of non-pregnant animals through evaluation of luteal function between 18 to 20 days post-AI. To reach these objectives, Nelore cows will have the estrous cycle manipulated by hormonal treatments and their ovulations synchronized for timed-AI. Plasma progesterone concentrations and size and luteal blood flow will be measured between days 8 and 30 post-AI. As result, is expected that changes in ultrasonography characteristics of corpus luteum of pregnant and non-pregnant cows will be identified and will allow the early diagnosis of non-pregnant Bos Indicus beef cattle. (AU)