Document Type

Thesis - Open Access

Award Date

2019

Degree Name

Master of Science (MS)

Department

Animal Science

First Advisor

Joseph Cassady

Second Advisor

Kristen Hales

Keywords

Cattle, Corn, Enzymes

Abstract

The objective of this study was to quantify the differences in activity of jejunal maltase and isomaltase between 2 groups of steers with average dry matter intake (DMI) and differing average daily gain (ADG). Dry matter intake and ADG were measured in crossbred steers (n = 69). Jejunal mucosal samples were collected from 8 steers with the greatest (high) or least (low) ADG and average DMI (± 0.55 standard deviation). Homogenates of jejunal mucosa were incubated with increasing amounts of maltose and isomaltose to determine the disaccharidase kinetics. Neither the Km of isomaltase (P = 0.15) or maltase (P = 0.43) differed between group. The isomaltase Vmax expressed per gram of protein (P = 0.11) or tissue (P = 0.18), respectively, did not differ between groups of steers. While previous studies have indicated that disaccharidase expression is associated with differences in ADG, data presented here indicate that differences in enzyme activity at the end of a feeding period are minimal. The objective of the second study was to evaluate the impact of corn-grain processing on feeding behavior and growth performance. There were 3 diets fed which differed in grain processing; wholeshelled corn-based diet (WSC); a blended corn-based diet containing a 50:50 wholeshelled corn and high-moisture corn (BLD); and a high-moisture corn-based diet (HMC). Meal duration, average meal size, and number of meals differed across treatments (P < 0.01). For meal duration, HMC was greater (P < 0.01) than WSC and BLD which did not differ (P > 0.13). The average meal size was greatest for WSC which tended to differ (P = 0.07) from BLD, and differed (P < 0.01) from HMC which had the least kg of intake at each meal. The HMC treatment consumed the greatest number of meals and differed from WSC and BLD (P < 0.01); whereas, WSC had the least number of meals and tended to differ from BLD (P = 0.09). Though the growth performance resembled previous work, no differences in steer growth performance or DMI were detected in the current experiment.

Number of Pages

85

Publisher

South Dakota State University

Rights

In Copyright - Non-Commercial Use Permitted
http://rightsstatements.org/vocab/InC-NC/1.0/

Included in

Beef Science Commons

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