Efecto de la presincronización del celo pre-synch utilizando bajas dosis de progesterona en vacas Bos indicus sometidas a protocolos de inseminación artificial

Globally, in regions with tropical characteristics, zebu cattle (Bos indicus) predominate, particularly due to their great adaptation; However, productive levels present variability due to environmental, nutritional, and management factors. These factors positively or negatively influence the fertility of cows. Therefore, the objective was to evaluate the effects of presynchronization of heat by applying long-duration P4 (pre-0synch) in conventional AITF protocols and its influence on the pregnancy rate in Bos indicus cattle. The research was carried out in the province of El Oro in the canton of Piñas, Ecuador, for which a number of 90 animals were used, with a live weight of 500 kg ± 50 kg; age: 3 to 7 years, body condition: 3 ± 0.5 on a scale of 1 to 5 points, with 1 animal being extremely cachetic and 5 animals being overconditioned. The animals were kept under equal environmental, nutritional and management conditions in an extensive grazing regime and previously dewormed and vitaminized. The individuals were randomly distributed into two experimental groups: control group (conventional IATF protocol = T0), and experimental group = T1 (conventional protocol with the inclusion of progesterone P4 (long-acting). Ultrasound of the ovarian structures was performed (day -8,0,8,10) by means of transrectal ultrasonography to assess ovarian cyclicity and the diameter of both the right and left ovaries; in addition, pregnancy was determined by means of ultrasonography on day 40 of the protocol (day 30 post insemination). Significant differences were observed between the control and treatment groups in relation to body condition and follicular diameter of the right ovary (p<0.05). There was a greater association between the variables of follicular size of the right ovary with respect to the variable pregnancy, and a lower association between the variables age and follicular size of the right ovary and left ovary respectively. Therefore, as age advances in bos indicus (Brahmin) cows, the follicular diameter increases; Furthermore, the greater the follicular diameter of the right ovary, the greater the number of pregnant animals. On day 40 of the IATF protocol, a greater number of pregnant animals was observed in the treatment group (n=32; 64%) compared to the control group (n=24; 48%). Finally, in cows (Bos indicus – Brahaman) the pre-synchronization method (pre-sinch) through the use of long-acting progesterone (P4) in low doses of 100 mg in a conventional IATF protocol numerically increased the rate of gestation. Furthermore, extrinsic and intrinsic factors such as age, body condition (B.C.), preovulatory follicle size (mm) could positively or negatively modulate pregnancy rates in cattle. Although there were no statistical differences in pregnancy rates between the control and treatment groups, a higher numerical value was observed in the pregnancy rate. This increase in the pregnancy rate in the control 5 group is possibly due to the positive effect of pre-synchronization (P4) on folliculogenesis and oocyte quality.

• Autor principal: Aguirre Granda, Lizbeth del Cisne (author)
• Formato: masterThesis
• Idioma: spa
• Publicado em: 2024
• Assuntos: PROGESTERONA DE ACCION PROLONGADA; PRE-SYNCH; PREÑEZ
• Acesso em linha: https://dspace.unl.edu.ec/jspui/handle/123456789/29512