Author ORCID Identifier:

https://orcid.org/0009-0003-7280-2651

Date of Graduation

9-2025

Document Type

Thesis

Degree Name

Master of Science in Poultry Science (MS)

Degree Level

Graduate

Department

Poultry Science

Advisor/Mentor

Hargis, Billy

Committee Member

Danielle Graham

Second Committee Member

Juan Latorre Cardenas

Third Committee Member

Young Kwon

Keywords

Broilers; cecal; Heat Stress; Microbiome; Tracheal

Abstract

The rise in global temperatures has become a concern due to its significant impact on the agricultural sector, including poultry production. Heat stress caused by high temperatures directly affects animal welfare, health and productivity, leading to major losses in the poultry sector. In broilers, heat stress affects feed consumption, weight gain, mortality and may also lead to changes in the microbiome, which can increase the predisposition to disease and impact the overall performance of these animals. The aim of this thesis was to reproduce field conditions, simulating an increase in temperature, and to evaluate possible changes in the respiratory and intestinal microbiome. At the same time, to assess the possible potential compounds to mitigate the deleterious effects of HS. For this purpose, broiler animals were divided into groups according to treatment, where Lippia origanoides essential oil associated with herbal Betaine were used in two different concentrations in the diet (initial/growth/finishing). The animals were exposed to heat stress cyclically, starting on day 10 of life for 12 hours a day (8:00-20:00) until day 42. The cecal contents and tracheal lavage were collected to evaluate the possible changes in the microbiome of birds exposed to heat and, comparatively, birds that received supplementation with Lippia origanoides and herbal betaine. The first chapter consists of a brief review of this thesis. Chapter 2 provides a literature review of the physiological aspects of heat stress in poultry, the respiratory and cecal microbiome, as well as a brief review of essential oils and their applications in poultry farming. Chapter 3 covers the research carried out, demonstrating the results of using these phytogenic compounds in situations of heat stress in poultry production.

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