Browsing by Author "Sarsour, Albaraa Hisham"
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- Effects of Nutritional Manipulation on Poultry under Normal and Stressful ConditionsSarsour, Albaraa Hisham (Virginia Tech, 2021-11-01)Genetic selection for improved performance has necessitated the frequent update of amino acid requirements to support this improvement. The first objective of this dissertation was to investigate the tryptophan requirement of laying hens in peak production and the lysine and sulfur amino acid requirements of broiler chicks under a phase feeding scenario using different models. Digestible tryptophan requirements were estimated to be 137 for egg production, 133 for egg mass, and 133 for feed efficiency using the linear broken-line model. The lysine and sulfur amino acid requirement were estimated by conducting 3 experiments within the starter phase from 2 to 5, 5 to 8, and 8 to 11 days of age. The linear broken line estimate for digestible lysine was 1.22, 1.17 and 1.16% for BWG and 1.31, 1.21, and 1.14% for FCR in experiments 1, 2, and 3, respectively. The linear broken line estimate for sulfur amino acids was 0.82, 0.81 and 0.94% for BWG and 0.82, 0.80, and 0.90 for FCR in experiments 4, 5, and 6, respectively. The lysine requirements decreased from 2 to 5 to 8 to 11 days, however the sulfur amino acid requirements increased during that same period. This could be due to other roles that sulfur amino acids play in the body other than growth. The second objective of this dissertation was to investigate the effects of a direct fed microbial (DFM) on broilers exposed to a cyclic heat stress in 2 consecutive experiments. In this experiment, the heat stress treatment reduced body weight gain and lean tissue accretion from 0 to 35 d in both experiments. In Experiment 2, when the litter was reused BWG was increased by 36 g/bird with supplementation of DFM. Ileal digestibility at 28 d (2 hr post HS) was improved with DFM supplementation in both experiments. Serum FITC-d increased with HS at both 28 and 35 d. Serum FITC-d was generally decreased with DFM at 28 d but the response was inconsistent at 35 d. Overall, the results suggest that HS reduced broiler performance and DFM treatment improved intestinal permeability and nutrient digestibility responses to HS in both experiments but did not improve performance until built up litter was used in Experiment 2. The last objective of this dissertation was to investigate the effects of sulfur amino acids (SAA) on broilers exposed to a cyclic heat stress. As expected, HS reduced BWG and worsened FCR. The supplementation of SAA had no effect on live performance. At 28 d of age, supplementation of SAA to birds exposed to HS resulted in reduced intestinal permeability. The interaction was lost at 31 d, but HS still increased intestinal permeability (P ≤ 0.05). Potential oxidative damage was reduced by increased SAA supplementation as indicated by an increase in the reduced glutathione to oxidized glutathione ratio. These data suggest that intestinal permeability is compromised acutely to at least three days of heat exposure before the bird can adjust, but oxidative damage is more chronic building over the entire 7 d HS period. SAA might have some protective effect on both intestinal permeability and oxidative stress responses to HS.
- Lysine and sulfur amino acid requirements of broiler chicks over short time periods within the starter phaseSix experiments were conducted to validate the hypothesis that Lys and SAA requirements decrease within the starter phase using 3-d periods from 2 to 11 d of age. In the first 3 experiments, 7 diets were generated by adding L-Lys to a lysine-deficient basal diet in 0.10% increments, ranging from 0.85 to 1.45% digestible Lys. In experiments 4 to 6, and 7 diets were generated by adding 0.07% increments of DL-methionine to a SAA-deficient diet to produce diets ranging from 0.63 to 1.04% DSAA. The linear broken line estimate for digestible Lys was 1.22, 1.17, and 1.16% for BWG and 1.31, 1.21, and 1.14% for FCR in experiments 1, 2, and 3, respectively. The linear broken line estimate for DSAA was 0.82, 0.81, and 0.94% for BWG and 0.82, 0.80, and 0.90 for FCR in experiments 4, 5, and 6, respectively. These results indicated that Lys requirements decreased linearly as hypothesized, however, the SAA requirements did not follow same pattern.
- Tryptophan requirement of first-cycle commercial laying hens in peak egg productionSarsour, Albaraa Hisham; Lee, J. T.; Haydon, K.; Persia, Michael E. (2021-03)An experiment was conducted to evaluate the digestible tryptophan (Trp) requirement of laying hens from 22 to 34 wk of age. A total of 252 Hy-line W-36 laying hens were selected at 16 wk of age and allocated by weight (P = 0.90) to 7 dietary treatments resulting in 12 replicate cages of 3 birds for each treatment. A Trp-deficient basal diet was formulated using corn, corn gluten meal, and soybean meal for each of the 3 dietary phases and supplemented with synthetic L-Trp to provide 105, 119, 133, 147, 162, 176, and 190 mg digestible Trp on a daily basis over the experimental period. To adapt the hens to experimental diets, pullets were fed complete diets that contained increasing amounts of corn gluten meal. Hens received a controlled amount of feed daily based on feed intake expected under commercial conditions. Linear and quadratic brokenline, and quadratic polynomial models were used to estimate digestible Trp requirements based on hen-housed egg production (HHEP), egg mass (EM), and feed efficiency (FE). FE was calculated using EM and feed intake. Digestible Trp requirements were estimated to be 137, 183, and 192 mg/d for HHEP; 133, 180, and 183 for EM and 133, 177, and 173 for FE using linear brokenline, quadratic broken-line, and quadratic polynomial analysis, respectively. The quadratic broken line model in this experiment resulted in the best fit (R-2) for all parameters measured. Linear broken line estimates resulted in lower estimates that the other models, and HHEP resulted in higher estimated digestible Trp requirement than EM and FE.