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Descripción
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| Wheat is the main energy source in European broiler diets. Although many studies have been developed about its nutritive value, its accurate prediction and utilization by broilers is not elucidated yet. This thesis deals with the factors that affect wheat nutritive value for broiler chickens: physico-chemical variability in wheat grains, the use of NSP-degrading enzymes, wheat cultivar and origin, and nitrogen fertilization to wheat crop. Broilers (21 to 30 d of age) were offered complete diets including wheat samples at 55 or 70% from different origin and grown under different conditions. Ileal and fecal starch digestibility, rate of starch digestion, nitrogen-corrected metabolizable energy and animal performance were measured. Results suggested that starch and crude protein were the main factors affecting in positive and negative way, respectively, the nutritive value of wheat for broiler chickens. The different factors studied in wheat samples influenced both physico-chemical properties and nitrogen-corrected metabolizable energy of the wheat but not ileal and fecal starch digestibility. The use of NSP-degrading enzymes increased nutrient digestibility and nitrogen-corrected metabolizable energy but did not eliminate the differences among wheat cultivars. Subsequent experiments demonstrated that the increase in crude protein content of the wheat by crop nitrogen fertilization had no effect on rate of starch digestion. Wheat samples differed in their starch digestion rate but they could not be classified based on the name cultivar alone because cultivar origin also affected starch digestion rate. Animal performance was affected by the rate of wheat starch digestion and there was a narrow range where animal performance was maximized. It was concluded that the variability in the nutritive utilization of wheat is mainly affected by its starch digestion rate more than by its total starch digestibility. | |
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Internacional
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Si |
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ISBN
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978-90-8585-323-7 |
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Tipo de Tesis
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Doctoral |
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Calificación
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Sobresaliente cum laude |
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Fecha
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