Graduation Term

2024

Degree Name

Master of Science (MS)

Department

Department of Agriculture

Committee Chair

Jennifer Earing

Abstract

A variety of flavors, including sweeteners, have been used in animal feeds to improve feed palatability and increase feed intake by livestock (Chen et al., 2020). While many of these sweeteners are found in the form of carbohydrates, brazzein is a sweet-tasting protein. This study was conducted to identify the potential of brazzein to influence feed intake by livestock, using poultry as a model. The preliminary study's purpose was to develop methods appropriate for the subsequent feeding study. In the preliminary study, eight pens of five birds were fed one of four treatment diets: Control or the Control plus one of three yeast preparations (baker’s yeast, dry yeast, and wet yeast; included at a rate of 1.5%). Feed and water intake were measured daily; breast circumference, pelvis width, and back length of each bird were also measured daily. Following euthanasia on day 12, liver weight, heart weight, and breast weight were recorded from each bird. The Control group had greater average daily feed intake (ADFI; p <0.05), suggesting the control diet was a more palatable than those containing yeasts. Breast circumference and breast weight were the highest in the Control group (p < 0.05, p < 0.04, respectively); this group also had the highest feed intake. Other parameters measured (pelvis width, back length, heart weight, or liver weight) were not affected by treatment diet, suggesting that feed intake has less of an effect on those physiological measurements compared to breast circumference and weight. In the second trial, nine groups of three birds were fed one of three treatment diets: CON, YEA, or BRA. The CON diet was a commercially available poultry starter feed; the YEA diet was the control diet plus a preparation of saccharomyces cerevisiae included at a rate of 1.5%. In the third diet (BRA), saccharomyces cerevisiae yeast was modified to include the brazzein gene. Yeast was then grown, dried, and incorporated into the control diet at a rate of 1.5%. Feed and water were offered ad libitum; intake of each was measured daily. Breast circumference, pelvis width, and back length of each bird were also measured daily. Following euthanasia on day 21, liver weight, heart weight, breast weight, crop weight, and small intestine weight and length were recorded from each bird. No differences were identified between any of the diets for feed intake, water intake, breast circumference, pelvic width, back length, heart weight, breast weight, liver weight, small intestine length, or small intestine weight. Crop weight was significantly less for the birds on BRA (p <0.02), compared to those on CON or YEA. Results from this research suggest feeding yeast containing brazzein to growing broilers does not affect feed intake or growth performance. This is the first study in which brazzein-containing yeast was fed to livestock. Additional research investigating the impact of brazzein-yeast inclusion rates on palatability, intake, and performance is warranted.

Access Type

Thesis-Open Access

DOI

https://doi.org/10.30707/ETD2024.20240827063557687937.999971

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