Development of tropical-adapted herds facilitated by the use of dominant follicle removal technique

Viero Marchioretto, Paula

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https://hdl.handle.net/2142/121547 Copy

Description

Title

Development of tropical-adapted herds facilitated by the use of dominant follicle removal technique

Author(s)

Viero Marchioretto, Paula

Issue Date

2023-07-19

Director of Research (if dissertation) or Advisor (if thesis)

Wheeler, Matthew B

Department of Study

Animal Sciences

Discipline

Animal Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• dairy
• tropical-adapted
• crossbreeding
• food security
• dominant follicle removal

Abstract

With the increasing concern regarding food security, it is essential to improve livestock production to guarantee that animal-sourced foods are available for the population worldwide. The situation is more critical in the tropics, where the undernutrition levels are higher, livestock productivity is lower, resources are limited, and harsh environmental conditions are found. All of these issues have been worsened by global climate change. One of the suggested measures to approach food security in the tropics is developing animals that can sustain good production even under these more challenging conditions. One idea has been to explore and combine traits of interest from Bos taurus and Bos indicus cattle. For example, when focusing on dairy, Girolando (Holstein – B. taurus – X Gyr – B. indicus -) cattle in tropical regions overcome the high heat effects and diseases detrimental to pure Holstein cattle. These Girolando cross animals have proven to maintain production levels in the 10 to 40 liter range. However, not all crossbreeding programs have succeeded, highlighting the importance of well-structured, comprehensive cattle improvement programs designed to align with local social and environmental conditions. Furthermore, a better understanding of these animals’ particularities is necessary for more efficient use of assisted reproductive technologies (ARTs), which will support faster distribution and accessibility to these genetics of interest. In vitro embryo production (IVEP) associated with ultrasound-guided Ovum Pick-up (OPU) is a widely used ART. Furthermore, there is evidence that follicular wave synchronization by dominant follicle removal (DFR) has positively affected OPU outcomes. However, protocols associating DFR and OPU are commonly combined with exogenous hormone administration and are well-established for only a few cattle breeds. These factors may lead to increased costs and decreased success of the procedure. Therefore, we tested the effect of DFR on OPU yields when applied at random days of the estrous cycle of ½ and ¼ Girolando donors (n= 125, 36.09±7.79 months old, and n= 110, 21.96±1.32 months old, respectively). The study characterized the ovarian response to this technique and aimed to identify the preferred interval DFR-OPU for those animals, considering the breed composition (½ and ¼). In our study, DFR was performed 48h or 72h before OPU, and the ovarian follicular population (grouped by size) and quality (grade I-IV) of cumulus-oocyte complexes (COCs) recovered from OPU were evaluated. A MIXED procedure was used to analyze the effect of treatment (DFR interval), breed composition and the interaction of treatment and breed composition, having age as a covariate. Donor and the interaction of donor, period of the year and year were random effects. The results are presented as LSM ± SEM. The DFR 48 h and 72 h groups had higher (18.39 ± 1.42 and 14.98 ± 1.42, P = 0.0002) estimated number of medium-size follicles (more developed) compared to the control group (no DFR) (10.84 ± 1.42) at OPU. Besides that, the highest quality COCs were greater at OPU with DFR 48h (2.09 ± 0.31, P = 0.004) than DFR 72 h (1.11 ± 0.31) and control (0.92 ± 0.31). Although no treatment and breed composition were present, ½ Girolando have significantly greater medium and total follicles, and G IV than ¼ Girolando (18.3 ± 2.02, 33.34 ± 2.67, 5.52 ± 0.64, and 11.35 ± 2.02, 22.56 ± 2.67, 0.77 ± 0.64, respectively). The association of DFR with OPU on Girolando has advantageous effects, resulting in the aspiration of more developed follicles and possibly better-quality oocytes. Further investigation is necessary, accessing the effect of DFR on embryo production rate, englobing more Girolando crosses and ages. DFR is a tool that can be easily implemented in IVEP rounds to potentially increase the number of superior genetic embryos available, facilitating the supply of these genetics in the regions where they are most needed.

Graduation Semester

2023-08

Type of Resource

Thesis

Copyright and License Information

Copyrithg 2023 Paula Viero Marchioretto

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