1939 - Performance of Broiler Chicks Fed Various Levels of...

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Performance of Broiler Chicks Fed Various Levels of Dietary Lysine and Crude Protein K. G. Sterling,* G. M. Pesti,* ,1 and R. I. Bakalli* *Department of Poultry Science, University of Georgia, Athens, Georgia 30602-2772 ABSTRACT An experiment was conducted to establish a basal diet deficient in both protein and lysine. The re- sponses of broiler chicks to graded levels of lysine at two levels of CP were measured in diets mixed by two experimental methods (diet dilution and graded supple- mentation). Experiment 1 had a 2 × 3 factorial arrange- ment of treatments with three dietary CP levels (17, 20, and 23%) and two levels of lysine per CP level (35 and 48 g lysine/kg CP). Dietary CP and lysine levels had significant ( P < 0.001) effects on body weight gain (BWG), feed intake, and feed conversion ratio (FCR). In exp. 2, the lysine requirement of chicks (9 to 18 d of age) was estimated at two levels of CP in diets mixed by the diet dilution method. The requirements for lysine at 17% CP (as a percentage of CP) were estimated to be 4.45 ± 0.18% ( Key words : broiler, crude protein, lysine, requirement) 2003 Poultry Science 82:1939–1947 INTRODUCTION In the early 1950s Almquist (1952) concluded that the level of an indispensable amino acid required for optimum chick performance was a positive linear function of the dietary CP level. This relationship was based on the results of Almquist (1949) and Almquist and Merritt (1950) for methionine and arginine, respectively. Further, Almquist’s (1952) plot of the data from Grau (1948) and Grau and Kamei (1950) revealed another aspect of the relationship between lysine and methionine and CP levels. Almquist noted that the relationship between the lysine and methio- nine requirements and dietary CP level were not similar and that as the dietary CP level increased the requirements decreased as a proportion of CP (Figure 1). This assumption was later challenged by Boomgaardt and Baker (1970, 1971, 1973) and Nelson et al. (1960), who reported that lysine, tryptophan, and methionine were required as constant pro- portions of CP, respectively (Figure 2). However, more recent studies have found the lysine (Abebe and Morris, 2003 Poultry Science Association, Inc. Received for publication January 28, 2003. Accepted for publication May 12, 2003. 1 To whom correspondence should be addressed: gpesti@arches. uga.edu. 1939 for BWG (R 2 = 0.83) and 4.33 ± 0.16% for FCR (R 2 = 0.81). Similarly, the requirements at 23% CP were 4.34 ± 0.16% for BWG (R 2 = 0.84) and 4.35 ± 0.13% for FCR (R 2 = 0.89). In exp. 3, the lysine requirement of chicks (10 to 18 d of age) was estimated at two levels of CP in diets mixed by the graded supplementation method. The requirements for lysine at 18.5% CP were 5.17 ± 0.25% for BWG (R 2 = 0.80) and 4.26 ± 0.15% for FCR (R 2 = 0.85). Similarly, the requirements at 23% CP were 4.59 ± 0.17% for BWG (R 2 = 0.83) and 4.71 ± 0.16% for FCR (R 2 = 0.88). Results of a t -test show that the requirements were not significantly
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1939 - Performance of Broiler Chicks Fed Various Levels of...

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