Effect of Varying Protein Levels and Amino Acids on Growth Performance, Gas Emission, Organ Weight, and Body Condition Score in Laying Chicks

There is increasing interest among nutritionists in formulating reduced crude protein (CP) diets for poultry. Nearly a century of research has offered biochemical insights into the effects of reduced CP diets in broilers but practical implementation of such diets for laying hens remains limited. Therefore, this study aims to investigate the effect of varying crude protein (CP) and amino acids (AA) levels on growth performance, gas emission, organ weight, and body condition score in laying chicks. n=480, 1d old chicks were allocated into six treatment groups with 5 replicates of 16 birds/pen. The dietary treatments for Phase 1 (0-6 weeks) were as follows: CON - 18.5% CP with 100% digestible AA; TRT1 - 18.5% CP with 100% digestible AA; TRT2 - 18.5% CP with 105% digestible AA; TRT3 - 18.0% CP with 100% digestible AA; TRT4 - 18.0% CP with 100% digestible AA; and TRT5 - 18.0% CP with 105% digestible AA. In Phase 2 (6-16 weeks), the CP level was reduced by 2% in the CON, TRT4, and TRT5 diets, and by 2.5% in TRT1, TRT2, and TRT3 diets, while the AA levels remained consistent in all treatments. Our study demonstrates that slight variations in protein levels and AA have no impact on growth performance, gas emission, organ weight, and body condition score in laying chicks. In summary, we infer that poultry diet can be flexible and potentially reduce protein levels if ensuring sufficient AA, thus optimizing performance without negatively affecting the growth.

Keywords:
Laying chicks; growth performance; digestible amino acid; crude protein