Date of Award

6-2025

Degree Name

MS in Agriculture - Animal Science

Department/Program

Animal Science

College

College of Agriculture, Food, and Environmental Sciences

Advisor

Ike Kang

Advisor Department

Animal Science

Advisor College

College of Agriculture, Food, and Environmental Sciences

Abstract

The poultry industry is constantly searching for new nutritional strategies and better feed conversion ratio to enhance broiler growth and productivity. Microalgae have been shown to improve broiler performance and health depending on species and supplementation levels. The objective of this study was to determine the effects of Spirulina supplementation (Experiment I) and Nannochloropsis supplementation (Experiment II) on broiler production performance, intestinal morphology, and gut microbiology. In Experiment I, a total of 270 broiler chicks (one-day-old Ross 708) were obtained from a local hatchery after vaccinating against Newcastle, Marek’s disease, and Infectious Bronchitis. They were weighed and sorted into 18 floor pens (4’x4’ each, 15 birds/pen). The birds were then fed isonitrogenous and isoenergetic corn-soybean meal-based diets containing graded levels of Spirulina (0%, 2.5%, and 5%). Birds were fed ad libitum for 6 weeks with a three-phase feeding program consisting of starter (0-2 weeks), grower (2-4 weeks), and finisher (4-6 weeks) diets. Initial body weights were measured, and subsequent body weights and the amounts of feed intake were measured weekly. Body weight gain and feed conversion ratio were then calculated. On day 45, 18 birds were randomly selected and were conventionally processed. Gut samples were taken to test intestinal morphology and gut microbiology. In Experiment II, a total of 270 broiler chicks (one-day-old Ross 708) were obtained and managed as in Experiment I, expect their diets containing graded levels of Nannochloropsis (0%, 2.5%, and 5%)

Data were analyzed with repeated measures ANOVA. Results showed that there was no significant difference in feed intake, feed conversion ratio, and body weight between the control and algae birds regardless of algae type and supplementation level (P > 0.05). No significant difference was observed for villi height (V), crypts depth (C), and the V/C ratio regardless of algae treatment and supplementation level (P > 0.05). However, the birds with Spirulina and Nannochloropsis promoted a beneficial gut microbiome composition, favoring fiber-fermenting and probiotic-associated bacteria while maintaining microbial population balance. Having no significant beneficial effects on broiler performance, the supplementations of Spirulina and Nannochloropsis at 2.5 to 5% levels appear to be not ideal especially when the price of both microalgae (e.g., Spirulina) is relatively more expensive than traditional corns and soybeans.

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