2250 - METABOLISM AND NUTRITION Effects of Fortifying Low...

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METABOLISM AND NUTRITION 2008 Poultry Science 87:2250–2258 doi:10.3382/ps.2007-00499 Key words: crude protein, amino acid, ammonia, uric acid, broiler ABSTRACT A study was conducted in a completely randomized design to evaluate the performance, excre - ta characteristics, and some blood nitrogen metabolite concentrations of 28-d-old male broilers fed 4 experi - mental diets in which CP was decreased in a stepwise manner from 23 to 17%. The other 4 diets were formu - lated to have 19 and 17% CP, in which 2 of them con - tained an additional 10% of particular essential amino acids (EAA) and 2 were supplemented with Gly and Glu. Ileal digestible quantities of all EAA were almost equal in the diets, and total amount of each EAA was maintained at or above NRC requirements. Decreasing dietary CP below 19% depressed performance and ap - petite and increased fat deposition in the whole body and abdominal cavity significantly. Adding the Gly and Glu mixtures to low-CP diets improved performance and decreased fat deposition. Uric acid, moisture, and acidity of excreta were decreased by reduction of di- etary CP; excretory ammonia level was increased in 17% CP diets. Blood ammonia level was increased and plasma uric acid was decreased with reduction of CP to 17%. Supplementing Gly and Glu increased plasma and excretory uric acid level in spite of decreasing blood ammonia concentration. The aminostatic hypothesis cannot explain the sharp reduction in appetite in this experiment, because alteration of dietary CP had no significant influence on most plasma free amino acid levels. Therefore, reduction of CP to 19% not only does not impair performance but also decrease nitrogen, ammonia, and pH of excreta that may improve upon litter and air quality. Adding large amounts of crystal - line EAA to diets with low intact CP increased blood and excretory ammonia concentration, which due to its negative effects on tissue metabolism may be the main cause of retarded growth and appetite in decreased CP diets below 19%. Effects of Fortifying Low Crude Protein Diet with Crystalline Amino Acids on Performance, Blood Ammonia Level, and Excreta Characteristics of Broiler Chicks N. F. Namroud, 1 M. Shivazad, and M. Zaghari Department of Animal Science, University of Tehran, Karaj, Tehran, Iran INTRODUCTION Attempts to decrease CP content of broiler diets have been successful to a point, but most researchers agree that reduction of CP has some noxious effects on per- formance and appetite. This failure is seen even with providing all requirements for those amino acids con- sidered as essential. Failure to obtain optimum result in performance may be attributed to one or more of the following factors: lack of nitrogen pool to synthe- size nonessential amino acids ( NEAA ); insufficiency of body capacity to meet all NEAA requirements espe- cially Gly, Ser, Pro, and Glu; decreased level of potas - sium or altered ionic balance; and imbalances among certain amino acids such as Arg to Lys, Lys to Thr, be
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This note was uploaded on 07/28/2011 for the course VET 4335 taught by Professor Sakomura during the Spring '11 term at University of South Pacific.

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2250 - METABOLISM AND NUTRITION Effects of Fortifying Low...

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