Semester

Spring

Date of Graduation

2025

Document Type

Thesis (Campus Access)

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Animal and Nutritional Sciences

Committee Chair

Joseph Moritz

Committee Co-Chair

Eugene Felton

Committee Member

Eugene Felton

Committee Member

Marie Krause

Abstract

In Chapter 2, the thermal dynamics of feed manufacturing, particularly during steam conditioning and pellet die extrusion, can significantly influence moisture incorporation and the stability of exogenous feed enzymes. The study investigates how ambient temperature interacts with conditioning temperature to affect moisture addition, pellet production efficiency, and enzyme activity. A split-plot design was used, with two ambient temperature settings (−1°C and 16°C) and three conditioning temperatures (66°C, 74°C, and 82°C). Increased conditioning temperatures raised both conditioned mash and hot pellet moisture levels (P < 0.05) regardless of ambient temperature. A significant interaction between ambient and conditioning temperature affected production rate (P = 0.0357), with production improving at 16°C ambient conditions but not at −1°C. Pellet mill motor load decreased with higher conditioning temperatures (P = 0.0002) and tended to decrease under warmer ambient conditions (P = 0.0647). While phytase activity remained stable across the board, carbohydrase activity declined with increasing conditioning temperature and higher ambient temperature (P < 0.05). This was potentially due to increased heat transfer and the Leidenfrost effect during warmer conditions. Findings suggest ambient temperature plays a role in modifying steam dynamics, enzyme viability, and pelleting performance, with implications for nutrient availability and process optimization in commercial feed manufacturing.

In Chapter 3, Sodium bisulfate (SB), a hygroscopic acidifier commonly used in poultry litter treatments, has potential benefits as a feed additive for improving both feed manufacturing and broiler performance. This study evaluated the effects of two inclusion levels of SB (2.7 and 3.6 kg/ton) in phytase-supplemented, calcium- and phosphorus-deficient broiler diets across starter, grower, and finisher phases. Five dietary treatments were formulated: a positive control (PC), a negative control (NC) with reduced calcium and phosphorus, NC + phytase, and NC + phytase with either 2.7 or 3.6 kg/ton SB. All diets were evaluated for feed pH, pellet quality, feed mill energy usage, broiler performance, nutrient digestibility, and excreta pH. SB inclusion reduced feed pH (P < 0.05) and improved feed manufacture by decreasing pellet mill motor load and hot pellet temperature while increasing pellet durability in a phase-specific manner (P < 0.05). Broilers fed SB at 2.7 kg/ton alongside phytase showed improved Day 18 live weight gain and feed conversion ratio (FCR) compared to NC-fed birds (P < 0.05). Tibia ash content was greater in phytase-containing diets, with intermediate values compared to PC and NC groups (P < 0.05). SB also lowered excreta pH on Days 7 and 14 (P < 0.05), suggesting improved gut acidification and nutrient utilization. These findings indicate that SB, particularly at 2.7 kg/ton, can enhance feed manufacturing efficiency and early broiler performance through its acidifying and moisture-retaining properties.

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