Effect of varying levels of dietary energy and protein on broiler performance: a review

The broiler meat sector is one of the most valuable contributors to food security in most developed and developing countries, thus, ensuring its viability is crucial. Feed energy (ME) and protein (CP) are jointly the greatest feed constituents and cost factors in broiler production. And these have been shown to influence broiler performance significantly. The relationship between these feed components is commonly described as a ratio of their dietary densities. Different ratios (narrow to wider) will influence overall performance measures differently and effects on performance parameters such as feed intake (FI) and the average daily gain (ADG) and feed conversion ratio, or efficiency (FCR or FCE) (in a range of determined ratios) can be linear or non-linear. On main effects, high ME will usually decrease FI and exacerbate excessive fat deposition. At the same time, dietary CP/amino acid (AA) density is directly proportional to carcass and breast meat yield. Overall, a proportionate increase in both ME and protein while maintaining a constant ME: CP ratio (as per breeder or NRC recommendations) will result in the best broiler responses. The optimal balance can be determined through modelling responses for various production goals and conditions.