Doctoral Dissertations

Date of Award

5-1999

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Animal Science

Major Professor

K. R. Robbins

Committee Members

Alan Mathew, M. O. Smith, F. A. Draughon, D. Golden, J. Bailey

Abstract

Three experiments were conducted utilizing male broilers to determine the effect of Avizyme® on non starch polysaccharides in rye-based diets. Avizyme® which contains 2500 units of xylanase and 800 units of protease/g was added to the experimental diets at the rate of 0, 0.05 and 0.1%. Feed efficiency, weight gain and water consumption were measured as indices of performance, whereas lactobacilli, total pathogenic clostridia and Salmonella typhimurium populations assessed gastrointestinal health and potential food safety hazards. Microflora were determined in the crop, jejunum, ileum and cecum. Volatile fatty acids (VFA) determinations in the distal ileum assessed fermentation activity. Interactions of VFA with microflora, gut mucosa and performance were assessed. DNA, RNA and protein of mucosal tissue were determined as indices of gut morphology and cellular activity.

The addition of Avizyme® to rye-based diets consistently improved feed efficiency and weight gain which was equal to that observed in corn-based diets (P < 0.05). Water : feed consumption ratio declined significantly with the addition of the enzyme to the rye-based diets (P < 0.05). Performance was unaffected by the carrier state in birds challenged with Salmonella typhimurium.. Acetate concentration in rye-based diets supplemented with Avizyme was 5 fold higher than that observed in the corn-based diets( P < 0.03). That increase was positively correlated ( r = .66) with increased mucosal mass in the rye-based diets. Mucosal protein:DNA and RNA:DNA ratios were significantly higher during week one in birds fed rye-based diets( P < 0.01). Lactobacilli populations were relatively stable throughout the experimental period irrespective of treatment. Clostridia declined with the addition of Avizyme in birds not challenged with Salmonella typhimurium. When birds were challenged, clostridia populations remained stable and acetate levels were low. Salmonella typhimurium tended to increase with the addition of Avizyme and persisted longer and at a higher level in rye based diets supplemented with the enzyme ( P < 0.05). Clostridium spp. were higher in the cecum regardless of grain type but Salmonella typhimurium was recovered primarily in the cecum and crop. (Key words: Fermentation, mucosa, DNA, Salmonella, clostridia, broilers.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS