Browsing by Author "Wen, Jinlei"

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    Effect of amino acids and vitamin D3 on performance and biological responses in poultry
    Wen, Jinlei (Virginia Tech, 2018-06-08)
    As productive performance is improved by breed selection, amino acid requirements may change to support this higher performance in poultry. The first objective of this dissertation was to update the valine and tryptophan requirement of small-framed laying hens and the lysine requirement of young broilers using empirical dose-response methods. The tryptophan requirement was estimated as 155.8 mg/d for egg mass, 153.2 mg/d for egg production and 140.4 mg/d for feed conversion ratio using a linear broken line model. For valine, the requirement was highest for egg mass, 597.3 mg/d, followed by egg production, 591.9 mg/d and feed conversion ratio (FCR), 500.5 mg/d. The lysine requirement of young chicks was estimated by conducting four short term experiments from 1 to 3, 3 to 5, 5 to 8 and 8 to 11 days of age, respectively. The lysine requirement from 1 to 3, 3 to 5 and 5 to 8 days of age were not able to be estimated as no dose response was observed on growth performance most likely due to an overestimation of the lysine requirement. Digestible lysine requirement from 8 to 11 days of age was 1.057%, 1.050% and 1.016% based on body weight gain, FCR and pectoralis major weight using a linear broken line model, respectively. In addition to determining amino acid requirements, research was conducted to develop a new bacterial protein meal for use in laying hens diets. The data suggested that diets containing 7.5% of the bacterial protein meal was able to at least maintain egg production in laying hens, but 15% bacterial protein meal resulted in reduced performance. The second objective of this dissertation was to investigate the effects of various concentrations of dietary vitamin D3 on pullet and laying hen performance, eggshell quality and bone health in laying hens. Pullets/hens were randomly assigned to five dietary treatments containing vitamin D3 from 1,681 to 68,348 IU/kg diet from day of hatch until 68 weeks of age. These data suggested that dietary vitamin D3 fed at 68,348 IU/kg resulted in reduced egg production, but vitamin D from 8,348 to 35,014 IU/kg diet maintained egg production, increased egg vitamin D content in a dose dependent manner, and generally increased both eggshell quality and pullet and hen bone mineral status.
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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).