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Unformatted text preview: Variations in the Digestible Lysine Requirement of Broiler Chickens Due to Sex, Performance Parameters, Rearing Environment, and Processing Yield Characteristics A. R. Garcia,* A. B. Batal,* 1 and D. H. Baker† *Department of Poultry Science, University of Georgia, Athens 30602-2772; and †Department of Animal Science, University of Illinois, Urbana 61801 ABSTRACT Four experiments were conducted to eval- uate variations in the digestible lysine (DLYS) require- ment estimates of broilers due to rearing environment, sex, or growth performance during the starter period (7 to 21 d) and due to sex, growth, and carcass yield charac- teristics during the grower period (21 to 38 d). In the first 3 experiments, chicks were allocated to either battery or floor pens. The fourth experiment was conducted during the grower period with birds reared in floor pens only. All the studies used a lysine-deficient corn-soybean meal- corn gluten meal basal diet formulated to be isonitrogen- ous and isocaloric. Treatments consisted of 5 graded lev- els of DLYS varying from 0.70 to 1.21% in the first 3 experiments and from 0.73 to 1.13% in the fourth experi- ment. The DLYS requirement was estimated by broken- line methodology based on body weight gain (BWG) and gain:feed ratio (G:F) for the starter period, and the same variables plus breast meat yield for the grower period. Key words : digestible lysine requirement, broiler, sex, rearing environment, growth performance 2006 Poultry Science 85:498–504 INTRODUCTION Lysine is the second limiting amino acid ( AA ) for poul- try fed corn-soybean meal diets, and because it is only used for protein synthesis, it has been chosen to express all other essential AA as a percentage of Lys, under the ideal protein concept (Baker and Han, 1994; Emmert and Baker, 1997; Baker et al., 2002). Therefore, it is crucial to obtain an accurate Lys requirement if that system is to be used. However, many factors must be considered in estimating AA requirements, such as the strain of the birds, type of diets, levels of other nutrients, age, sex, and rearing environment (Baker et al., 2002). To date, possible differences in the requirement of not only Lys, but all the essential AA due to sex, performance parameters such as body weight gain ( BWG ), gain to feed ratio ( G:F ), or 2006 Poultry Science Association, Inc. Received July 15, 2005. Accepted October 23, 2005. 1 Corresponding author: email@example.com 498 During the starter period, the average DLYS requirement of males based on BWG was slightly higher than that of females reared in battery (0.96 vs. 0.94%) or floor pens (0.98 vs. 0.93%). However, based on G:F, the average DLYS requirement of females was slightly higher than that of males reared in both battery (0.99 vs. 0.96%) and floor pens (1.01 vs. 0.99). The DLYS requirement based on G:F was higher than that based on BWG only for females in both rearing environments. Rearing environ- ment did not affect the DLYS requirement of broilers...
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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.
- Spring '11