2005 - Effects of Different Dietary Ideal Protein Levels on...

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Effects of Different Dietary Ideal Protein Levels on Male and Female Broiler Performance During Different Phases of Life: Single Phase Effects, Carryover Effects, and Interactions Between Phases P. J. A. Wijtten,* ,1 A. Lemme,† and D. J. Langhout* *Provimi B.V., Rotterdam, The Netherlands; and †Degussa AG, Feed Additives Applied Technology, Hanau, Germany ABSTRACT Several experiments in which the dietary ideal protein (IP) levels were increased indicate that with current IP recommendations the maximum performance of broilers will not be achieved. However, available data of this IP-increment approach is scarce and, for the starter phase, entirely lacking. The objective of the present study, therefore, was to generate data regarding the effects in the starter phase and to test the impact of adequate vs. high IP levels in preceding phases on the response to IP increment in the phase under study. To evaluate this, an IP dose response in the starter phase and factorial arrangements combining adequate or high IP levels in starter and grower diets with low, adequate, or high IP levels in finisher diets were carried out with male and ( Key words : broiler, ideal protein, sex, age, phase) 2004 Poultry Science 83:2005–2015 INTRODUCTION Besides energy, amino acids (AA) are the most critical dietary factors determining feed costs and performance in the broiler industry. Therefore, it is of considerable financial importance to continuously increase our knowl- edge of broiler requirements for AA. In the 1950s, Almquist (1952) established that growth rate depends on the intake of the first limiting (indispens- able) AA. Animal performance, furthermore, improves in response to supplementation of that AA in the diet up to the level that the second indispensable AA becomes limiting. This theory has been fully accepted and is used in feed formulation practice. It is understood that requirements of poultry for AA are influenced by dietary, environmental, and genetic factors. The ideal protein (IP) concept has been developed, in which AA requirements are often expressed as ratio to Lys, leading to an ideal AA profile in which all indispens- able AA are equally limiting. This approach was first 2004 Poultry Science Association, Inc. Received for publication April 27, 2004. Accepted for publication August 29, 2004. 1 To whom correspondence should be addressed: pwijtten@nl. provimi.com. 2005 female broilers. Enhanced dietary IP levels in the starter diet increased BW gain in the starter phase and in the consecutive grower phase. Moreover, it was shown that a delay in BW gain due to suboptimal IP levels in the starter diet could only be partly compensated for in later phases of life. These results demonstrate the need for a reevaluation of IP levels used in practical starter diets. Feed conversion efficiency and BW gain responses to in-
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2005 - Effects of Different Dietary Ideal Protein Levels on...

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