Further evaluation of a slope-ratio precision-fed rooster assay for relative bioavailable energy values for fats and oils

Von Schaumburg, Patrick Connor

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Description

Title

Further evaluation of a slope-ratio precision-fed rooster assay for relative bioavailable energy values for fats and oils

Author(s)

Von Schaumburg, Patrick Connor

Issue Date

2017-11-20

Director of Research (if dissertation) or Advisor (if thesis)

Parsons, Carl M.

Committee Member(s)

• Koelkebeck, Kenneth
• Cattai de Godoy, Maria Regina

Department of Study

Animal Sciences

Discipline

Animal Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Slope-ratio
• Precision-fed
• Rooster
• Chick
• Bioavailable
• Fats
• Oils
• Poultry

Abstract

Five slope-ratio precision-fed rooster assays and one limit-fed chick growth assay were conducted using different fats/oils at several increasing dietary levels to determine relative bioavailable energy values. In Experiment 1, roosters were precision-fed 0, 5, or 10% of five different fats as part of a ground corn diet totaling 30 g of diet per rooster. Refined soy oil (the reference oil), poultry fat, crude soy oil, crude corn oil, and palm oil 1 were all evaluated. In Experiment 2, roosters were precision-fed 0, 5, or 10% of either a refined corn oil set at 100% (RCO), a vegetable acid oil, or a soy acid oil as part of a ground corn diet. In Experiment 3, roosters were precision-fed 0, 5, 10, 15, or 20% of either RCO, palm oil 1, tallow, or choice white grease as part of a ground corn diet. In Experiment 4, roosters were precision-fed 0, 5, 15, or 20% of either a vegetable-blend acid oil or palm oil 2 as part of a ground corn diet to determine if 20% lipid inclusion was physically possible to feed and if a linear response in nitrogen-corrected true metabolizable energy (TMEn) would be obtained. Experiment 5 was a limit-fed chick growth assay conducted using Ross 308 broilers. The broilers were limit-fed to 70% of their expected daily intake from 11 to 20 d of age and four different lipid sources (RCO, palm oil 2, choice white grease, and an acid oil) were tested at 0, 5, and 10% inclusion levels. Diets consisted of graded levels of supplemental lipid added to a corn-soy basal diet at the expense of cellulose. The TMEn of diets (rooster assays) or body weight (chick assay) gain of chicks were regressed on supplemental lipid level or intake using multiple linear regression. Relative bioavailability values (RBV) for each lipid were calculated as the regression coefficient of the test lipid divided by the regression coefficient of the reference lipid (RSO or RCO). In Experiment 1, only the RBV of palm oil 1 (82.5%) was significantly lower (P < 0.05) than soy oil (100%). In Experiment 2, no significant differences (P > 0.05) in RBV were observed for the vegetable acid oil or the soy acid oil and RCO. In Experiment 3, both the RBV of tallow (74.4%) and palm oil 1 (82.9%) were significantly lower (P < 0.05) than RCO (100%), while the RBV of choice white grease (98.7%) was not significantly different (P > 0.05) than RCO. It was observed that the differences among fat sources were often greater at the higher inclusion levels of 15 and 20% in the rooster assay. In Experiment 4, high linearity was observed for 0-20% levels of palm oil 2 and the vegetable blend acid oil (R2= 0.94-0.97). In Experiment 5, the RBV of palm oil 2 (80.5%) and choice white grease (85.4%) were significantly lower (P < 0.05) than the 100% for RCO, whereas the RBV of the vegetable blend acid oil (92.7%) was not significantly (P > 0.05) different from 100%. In general, the rooster results agreed well with the results obtained in the chick growth assay; however, using higher inclusion rates of 15 or 20% of the fats may increase the sensitivity of the rooster assay in detecting differences among lipid sources. A slope-ratio precision-fed rooster assay was also conducted to determine the relative metabolizable energy (ME) values of RCO and four test lipids, canola oil, poultry fat, oxidized canola oil, and oxidized poultry fat. Oxidation of the lipids was achieved by cyclic heating of the lipids for 60 h at 90 °C with ambient air being percolated through the lipids at 12 liters per min. The RBV of the lipids varied from 86.3% to 104%, but none of the test fat RBVs were significantly lower (P < 0.05) than the refined corn oil reference (100%); although the RBV of both the canola oil and poultry fat were numerically reduced by 11 percentage units by oxidation. Thus, the results of this study indicated that oxidization of the canola oil and poultry fat did not significantly reduce the RBV of the lipids.

Graduation Semester

2017-12

Type of Resource

text

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Copyright 2017 Patrick Von Schaumburg

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