Document Type

Dissertation - Open Access

Award Date

2019

Degree Name

Doctor of Philosophy (PhD)

Department

Animal Science

First Advisor

Tofuko Woyengo

Keywords

Canola co-products, Cold-pressed canola cake, Glucosinolates, High-amylose cornstarch, Hindgut pH, Nursery pigs

Abstract

Canola co-products have a high content of fiber and glucosinolates. Fiber reduces nutrient utilization in pigs, whereas glucosinolates are degraded to toxic products, which interfere with liver, kidney and thyroid functions. Negative effects of fiber can potentially be alleviated by fiber-degrading enzymes, whereas negative effects of glucosinolates in pigs can potentially be alleviated through reduction in hindgut pH. However, there is a lack of information on effects of supplemental fiberdegrading enzymes on digestion and fermentation characteristics of canola coproducts for pigs. Also, there is limited information on effects of reducing hindgut pH on toxicity of glucosinolates in pigs. Four experiments were conducted to fill these gaps in knowledge. The first experiment investigated effects of supplementing canola co-products with fiber-degrading enzymes on porcine in vitro digestion and fermentation of canola co-products. Supplemental fiber-degrading enzymes increased in vitro digestibility of canola co-products. The second experiment investigated effects of increasing levels of cold-pressed canola cake (CPCC) in diets for pigs from 0 to 40% on growth performance, organ weights, blood thyroid hormone levels. Growth performance, metabolic activity in liver and thyroid functions were negatively affected by dietary inclusion of CPCC at 40%. The third experiment investigated effects of reducing hindgut pH through dietary inclusion of high-amylose cornstarch (HA-starch) on the fore-mentioned response criteria and cecal concentration of glucosinolate degradation products in pigs fed diets that contained 40% CPCC. Dietary CPCC increased thyroid gland weight of pigs fed HA-starch-free diet, but not of pigs fed HA-starch-containing diet. Inclusion of HA-starch in CPCC-based diets increased isothiocyanate production in cecal digesta of pigs. However, nitriles were undetected in cecal digesta of pigs fed CPCC-based diets. Thus, the fourth experiment was conducted to determine effects of reducing pH on composition of glucosinolate degradation products in canola co-products using porcine in vitro fermentation technique. Reduction in fermentation medium pH from 6.2 to 5.2 increased production of indole- 3-acetonitriles. In conclusion, the results demonstrated that fiber-degrading enzymes can be supplemented to canola co-products-based diets for pigs to improve efficiency of nutrient utilization and that toxicity of canola glucosinolates can be alleviated through reduction in pH of hindgut of pigs.

Format

application/pdf

Number of Pages

207

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

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