Date of Graduation

8-2023

Document Type

Thesis

Degree Name

Master of Science in Poultry Science (MS)

Degree Level

Graduate

Department

Poultry Science

Advisor/Mentor

Sami Dridi

Committee Member

Michael Kidd

Second Committee Member

Sun-ok Lee

Third Committee Member

Wayne Kuenzel

Abstract

Heat stress is a major issue in the poultry industry, having numerous negative consequences for chicken productivity. Decreasing feed intake is one of these issues, which results in higher mortality and poor growth performance. Moreover, Herbal adaptogens, plant extracts that are also known as stress response modifiers, are metabolic regulators that improve an organism's ability to adapt to environmental stresses and minimize damage from such stressors. Previously, we published data indicating that herbal adaptogen supplementation increased feed intake under heat stress conditions. Therefore, we hypothesized that dietary herbal adaptogen supplementation might exert these effects through alteration of the expression of hypothalamic neuropeptides involved in appetite and feed intake in heat-stressed broilers. A total of 720 male broiler cobb 500 chicks were randomized to 12 chambers for three different diet treatments. As a control group, broilers in treatment 1 were fed a corn-soybean diet. The broilers in treatments 2 and 3 were supplemented with the herbal adaptogen in two different doses in control diets 500 g/1000 kg (NRPHY-500) and 1 kg/1000 kg (NR-PHY-1000), respectively. Broilers in 9 chambers were exposed to 35 °C for 8 hours (a cyclic heat stress condition) from d29 to d42, while 3 chambers were maintained at 24 °C (thermoneutral condition) for all 42 days. The real-time qPCR was performed to evaluate the gene expression of 17 hypothalamic neuropeptides that play a vital role in feed intake and appetite, and the data were analyzed using ANOVA. Only the gene expression of visfatin changed significantly (P = 0.0105) among the 17 genes studied, while the expression of the other neuropeptides remained unchanged. We concluded these findings suggested that adding adaptogen supplementation to broilers' diets could be a promising way to reduce the negative effects of heat stress by modulating hypothalamic genes that control appetite and feed intake. Keywords: broilers, heat stress, herbal adaptogen, feed intake, hypothalamic neuropeptides

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