Browsing by Author "Elliot, Michael"

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    The Effects of a Single Strain Bacillus subtilis DFM on pullet performance, laying hen performance, and egg quality when fed from day of hatch until 70 weeks
    Samper, Jordyn Marie (Virginia Tech, 2022-08-18)
    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.
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    Evaluation of the tryptophan requirement of small-framed first cycle laying hens
    Wen, Jinlei; Helmbrecht, Ariane; Elliot, Michael; Thomson, John E.; Persia, Michael E. (2017)
    Tryptophan is an essential amino acid, required for protein synthesis, and several metabolic processes in laying hens. Although required, the literature is mixed if tryptophan is considered the third or fourth limiting amino acid for laying hens and research on the tryptophan requirement in laying hens has been limited. The purpose of this experiment was to evaluate the tryptophan requirement of first cycle laying hens from 41 to 60 weeks of age. In total, 270 Hy-line W36 laying hens were randomly allocated to 6 treatments with 15 replicates of 3 birds for each experimental unit. Hens were maintained 3 to a cage (72 sq in/bird) in a multi-teared A-frame cage system within an environmentally controlled building. Hens were provided a 16:8 light schedule and 70 to 80 °F temperature program. A tryptophan deficient basal diet was formulated with corn, corn gluten meal and soybean meal with determined tryptophan, lysine and crude protein concentration of 0.096, 0.873, and 15.0%, respectively. Synthesized l-tryptophan was supplemented to the basal diet in 0.020% increments to generate experimental diets containing 0.096, 0.116, 0.136, 0.156, 0.176, and 0.196% tryptophan respectively. Hens were provided a controlled amount of feed daily resulting in approximately 95g/hen/d. The diet containing the lowest concentration of tryptophan resulted in reduced egg production and was halted at 45 weeks due to low performance with all other dietary treatments reaching the conclusion of the experiment at 60 weeks of age. Hen-housed egg production (HHEP) and mortality were monitored daily. Eggs were collected on two continuous days each week for feed conversion ratio (FCR) calculations and egg quality analysis. Single-slope broken line, multi-slope broken line and quadratic regression were used to estimate tryptophan requirement based on HHEP of the remaining five dietary treatments. Based on HHEP, optimum tryptophan requirement was 154.0, 142.8 and 193.7 mg/hen/d (single-slope broken line regression: Y=80.86+0.4871(X-154.02), R2=0.85; multi-slope regression: Y=3.127+0.5135X-0.3997(X-142.8), R2=0.85; quadratic regression: Y=-0.003046X2 +1.1802X-32.33, R2=0.85).
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    Evaluation of the valine requirement of small-framed first cycle laying hens
    Wen, Jinlei; Helmbrecht, Ariane; Elliot, Michael; Thomson, John E.; Persia, Michael E. (2017)
    Genetic selection has resulted in laying hens that are producing more eggs while consuming reduced amounts of feed over a laying cycle. As so, it is important to reevaluate the amino acid requirements of these new high performing hens. Valine is an essential amino acid required for protein synthesis, however, research on valine requirement has limited in laying hens. The purpose of this experiment was to evaluate the valine requirement in first cycle laying hens from 41 to 60 weeks of age. In total, 270 Hy-line W36 laying hens were randomly allocated to 6 treatments with 15 replicates of 3 birds for each replicate. Hens were maintained 3 to a cage (72 sq in/bird) in a multi-teared A-frame cage system within an environmentally controlled building. Hens were provided a 16:8 lighting schedule and 70 to 80 °F temperature program. A valine deficient basal diet was formulated with corn and peanut meal with determined valine, lysine and crude protein concentration of 0.515, 0.875, 13.4%, respectively. Synthesized l-valine was supplemented to the basal diet in 0.070% increments, resulting in experimental diets containing 0.515%, 0.585%, 0.655%, 0.725%, 0.795% and 0.865% valine, respectively. Hens were provided a controlled amount of feed daily resulting in approximately 95g/hen/d. Hen-housed egg production (HHEP) and mortality were monitored daily. Eggs were collected on two continuous days each week for Feed Conversion Ratio (FCR) calculations and egg quality analysis. Single-slope broken line, multi-slope broken line and quadratic regression were used to estimate valine requirement based on HHEP, egg weight (EW), egg mass (EM), and feed conversion rate (FCR). Based on HHEP, optimum valine requirement was 591.9, 492.0 and 740.8 mg/hen/d (single-slope broken line regression: Y=80.23 + 0.12219(X-591.9), R2=0.83; multi-slope broken line regression: Y=-0.607+0.1593X-0.1264(X-492.02), R2=0.86; quadratic regression: Y=-0.00019944X2+ 0.295507X-28.3124, R2=0.85).