Two experiments were conducted to determine the effects of various alternatives to antibiotics in broilers grown on used litter on performance, intestinal lesion scores, body composition, and cecal volatile fatty acid (VFA) concentrations. The first experiment used a corn-soybean meal based basal diet to generate a negative control (NC) diet (without treatment), a Bacillus licheniformis probiotic containing diet (NC + 0.10% DFM1), and four diets that contained various concentrations of a Bacillus subtilis probiotic (NC + 0.05% DFM2, NC + 0.10% DFM2, NC + 0.20% DFM2, and NC + 0.40% DFM2). Experimental diets were fed to broilers over a 42-day period. Body weight gain (BWG) was depressed from d 0-28 and d 0-42 with supplementation of 0.10% DFM1 and 0.05% DFM2 compared to NC fed birds (P ≤ 0.05), with no differences among the remaining treatments and the NC fed birds (P > 0.05). Feed intake (FI) and mortality corrected feed efficiency (FEm) were not different over the 0-42 day period. No differences in oocyst shedding, lesion scores, body composition or cecal VFA production were observed (P > 0.05). Consistently low lesion scores were indicative of a mild coccidial challenge. The second experiment utilized a corn-soybean meal basal diet to generate experimental treatment diets. The basal diet without additional supplements was fed to two groups of control birds, one on clean pine shaving litter (PC) and a second on used litter (NC). Treatment groups were fed the same diet, supplemented with butyrate for the first 14 days (NC + But 0-14), botanicals from d 15-43 (NC + Bot 15-43), butyrate from d 0-14 and botanicals from d 15-43 (NC + But 1-14/Bot 15-43), and butyrate from d 0-43 (NC + But 1-43). Butyrate supplementation reduced BWG from d 0-14 (P ≤ 0.05), but there were no differences in BWG from 0-43 d (P > 0.05). Feed intake was reduced for the NC + But 0-14 group from d 0-43 in comparison to both PC and NC. Lesion scores in the jejunum were reduced with supplementation of butyrate alone, fed for either d 0-14 or d 0-43 (P ≤ 0.05) and is an indication of a mild coccidial infection due to the used litter. Although there were no significant differences among treatments, overall performance was above industry expectations, likely due to the mild fall weather. These two experiments indicate that there are numerous factors involved in the efficacy of antibiotic alternatives, at least partially explaining the inconsistent results observed in the published literature. / Master of Science / Recently, increased regulations and customer demand have restricted and reduced the use of antibiotics in the poultry industry. Historically, antibiotics were used in poultry feed at sub-therapeutic levels to improve performance and prevent the incidence of clinical and subclinical disease. Since the reduction of antibiotic use, many producers have experienced reduced performance resulting in reduced profits. The limited use of antibiotics can also present an animal welfare issue associated with increased sub-clinical and clinical disease. Many researchers are investigating alternative feed additives that will both improve performance and prevent disease, including probiotics, organic acids, and botanical products. Previous research has demonstrated the ability of these alternative to positively, if inconsistently, influence the performance and health of broiler chickens. Therefore, the objective of this thesis is to investigate the effects of two probiotic bacteria fed at various concentrations and the effects of butyric acid and botanicals, fed alone, or in combination, on the performance, intestinal lesion scores, body composition, and cecal volatile fatty acid concentrations of broiler chickens raised on used litter. In these experiments, the used litter is representative of a mild disease challenge that would likely be present in a commercial poultry setting. Overall, there were few differences with the treatment of broilers with probiotic bacteria, but the lowest inclusions slightly reduced body weight gain compared to the control fed broilers. Butyric acid supplementation reduced body weight gain over the first 14 days, but these differences were no longer observed over the 0 to 42 day period. Although performance was not improved, butyrate did result in reduced intestinal lesion scores from the middle section of the small intestine, indicating potential health benefits with butyrate treatment. Overall, the data presented in this thesis suggest that there are a variety of factors that can alter the effectiveness of these alternatives in broiler production and care should be used in selection of antibiotic replacement tools.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/87088 |
| Date | 29 August 2018 |
| Creators | Lewis, Meredith D. |
| Contributors | Animal and Poultry Sciences, Persia, Michael E., Moritz, Joseph S., Pierson, F. William |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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