Direct-fed microbials (DFM) are a method to increase bird performance and health when antibiotics are removed or limited in the diet. The objective of this experiment was to determine the effects of a single strain Bacillus subtilis DFM on pullet performance, layer performance, and egg quality when fed from day of hatch until 70 weeks of age. In total, 576 Hy-Line W-36 laying hen pullets were randomly divided between two treatments (Control and DFM) on day of hatch across 12 cages for each of the treatments and maintained on those respective treatments for 70-weeks. The DFM was added at a target dose of 300,000 cfu/kg of feed. At the end of the 17-week pullet phase, DFM fed pullets resulted in reduced feed intake, improved FCRm with both similar body weights (P = 0.98) and body composition (P > 0.05) to the control fed pullets. At 17 weeks, 72 birds were randomly selected from each treatment and moved to 12 laying hen cages. At the end of the 52-week laying hen phase, DFM-fed hens had significantly higher hen-day egg production (P = 0.02), but decreased egg weights. No differences were reported in egg mass or feed intake, but FCR was significantly improved (P = 0.02) on a per dozen eggs basis, and improved (P = 0.06) on a g/g basis by 7.1 points with DFM-fed hens having an FCR of 2.016 and control fed hens having and FCR of 2.087. Supplementation of diets with DFM resulted in a trend in egg specific gravity, but no differences were reported in shell breaking strength or shell weight. Overall, supplementation of the DFM lowered feed intake and improved FCR without affecting body composition in the pullet phase, and increased production and improved FCR during the egg laying phase. / Master of Science / Due to the decreased use of antibiotics across the poultry industry, producers and allied companies are developing new methods to increase bird health and performance when antibiotics are removed from or limited in the diet. One such method is through the use of "good" bacteria or technically called Direct-Fed Microbials (DFM). Direct-fed microbials are defined as live microorganisms that when fed, confer a health benefit to the host. The goals of this thesis were to determine the effects of a Bacillus subtilis based DFM on pullet performance, laying hen performance, and egg quality when fed from day of hatch until 70 weeks of age. In the pullet phase, DFM-fed pullets had reduced feed intake and improved feed conversion ratio (the ratio of feed intake to body weight gain), with no differences in body weights or body composition at the end of the 17-week growth period. In the laying phase, DFM fed hens had significantly improved egg production, but lighter eggs compared to the control fed hens. Addition of the DFM significantly improved feed conversion ratio per dozen eggs by 5.3 points and reduced feed conversion ratio on a g/g basis by 7.1 points in the 52-week laying phase. Small improvements were noted in specific gravity, but no differences were reported in shell weight or shell breaking strength. When fed from day of hatch until 70 weeks of age, the Bacillus subtilis DFM allowed the pullets to reduce their feed intake, but maintain body development for egg production resulting in an improved feed conversion ratio (FCR) in the growth phase before egg production and once hens initiated egg production resulted in smaller eggs, but increased egg production and FCR in laying hens with minimal differences in egg quality. Therefore, the DFM may be able to be used in place of growth promoting antibiotics to help support efficient protein production.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/111557 |
| Date | 18 August 2022 |
| Creators | Samper, Jordyn Marie |
| Contributors | Animal and Poultry Sciences, Persia, Michael E., Greiner, Scott P., Elliot, Michael |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
Page generated in 0.002 seconds