Semester

Spring

Date of Graduation

2022

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Animal and Nutritional Sciences

Committee Chair

Joseph Moritz

Committee Co-Chair

Jacek Jaczynski

Committee Member

Jacek Jaczynski

Committee Member

Janet Tou

Committee Member

Ibukun Oganade

Abstract

There are many things that can be done to improve broiler performance including, but not limited to, pelleting, proper Lys inclusion, and exogenous enzyme supplementation. Pelleting has the ability to improve feed form, reduce wastage, improve bird performance metrics, and decrease pathogens within the feed. Pathogen reduction can be further reduced by hygienic pelleting practices which include an increase in temperature or retention time within a conditioner or hygieniser. However, hygienic pelleting can degrade valuable AA and enzymes (more specifically for the current thesis research Lys and phytase) and make them unavailable to the animal. Supplementing Lys to account for the loss can increase the price of feed production but can be balanced by the improvement in broiler LWG. Performing research on novel phytases to improve enzyme activity after the addition of heat and within the digestive tract of the bird critical in order to improve bird performance metrics. Evaluating high conditioning temperature and exposure time within the pelleting process (hygienic pelleting) in diets that vary in digestible lysine and corresponding amino acid ratio on Ross 708 starter broiler performance, amino acid digestibility, and requirement is the purpose of the initial study. A 5 x 2 factorial arrangement of treatments with 5 levels of digestible lysine (- 20%, -10%, 2019 Ross Broiler Starter Nutrition recommendation, +10%, and +20%) and 2 degrees of pelleting (Standard and Hygienic) was utilized in a randomized complete block design. Each treatment was fed to 12 replicate pens of 10 male broiler Hubbard x Ross 708 chicks for a 21-day period. On the morning following day 7, 14 and 21, birds and feed were weighed by pen for performance calculations and ileal contents were collected on d22 for AA digestibility calculations. Standard Pelleting and Hygienic Pelleting demonstrated a 1.19 and 1.37% Lys requirement, respectively, using the broken-line regression model. Performance data and the broken-line regression model suggest an approximate 10% increase in Lys and corresponding amino acid ratio relative to 2019 Ross Broiler Starter Nutrition Specifications for Hygienic Pelleting to provide optimal live weight gain. Hygienic Pelleting decreased amino acid digestibility and increased subsequent FCR when diets were formulated to decreased amino acid density. The assessment of novel exogenous phytase enzymes that can be added to the mixer prior to pelleting is important for the continual improvement of global broiler production. Two experiments were conducted to determine in vitro activity post pelleting and in vivo efficacy post feeding of a novel phytase. The objective of the first study was to determine activity and retention of a novel phytase enzyme (CJ Phytase) and a commercially available phytase (Quantum Blue 5G®) at different 30 second conditioning temperatures (75, 80, 85, and 90˚C) post-pelleting. The objective of the second study was to determine the effects of these phytase sources conditioned for 30 seconds at the 75˚C conditioning temperature on broiler performance, bone mineralization, and mineral digestibility. Experiment one consisted of a 2 (phytase source) x 4 (conditioning temperature) factorial arrangement. A conditioning temperature main effect (P=0.0003) demonstrated that activity of both phytase products decreased at 85˚C and decreased again at 90˚C. In experiment two, 2,304 Hubbard x Ross 708 birds were obtained and fed one of eight diets for a 42-day period. Diets included Positive Control, Negative Control deficient in calcium and Available P by 0.2%, and graded levels of NC+ CJ Phytase (250, 500, 1,000, 1,500, and 3,000 FTU/kg). In order to provide a commercially available comparison, an NC + Quantum Blue 5G 500 FTU/kg was also fed. All phytase additions increased AID P, d42 tibia ash percentage, and d0-42 LWG relative to the NC diet (P

Download

Share

COinS