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Abstract
1. An experiment was conducted to investigate if broilers can improve their performances and N-retention using choice feeding (CF).
2. Treatment 1 consisted of a standard three-phase feeding regime (SF). Treatments 2–7 were CF treatments with a high (HP) and a low protein (LP) feed offered simultaneously to the birds. Choice feeding started at day 1 or 8 and feeds were offered in mash form or as pellets.
3. When choice feeding was started at day 1 and the HP diet was mash, growth rates were increased (+4·2%) compared to SF, whereas all other CF treatments showed similar or significantly lower final body weights compared to SF. Feed conversion was increased for all CF strategies.
4. Highest yield and breast meat percentages were obtained if the low protein diet was pelleted. The amount of N excreted was increased for most choice feeding treatments as a result of the increased N-intakes and the less efficient growth.
5. Broilers were able to make a choice between two feeds differing in protein/amino acid contents starting as early as day 1, but choices were influenced by feed form. The results confirmed that very high protein/amino acid concentrations in the starter period are desirable to improve growth rates in fast-growing chickens.
Acknowledgements
Authors are very grateful to the technical personnel of ILVO institute for the careful execution of the trial. This study was partially supported by grants from Orffa Belgium.