Reducing dietary crude protein in broiler diets positively affects litter quality without compromising growth performance whereas a reduction in dietary electrolyte balance further improves litter quality but worsens feed efficiency

Abstract

Reducing crude protein (CP) in broiler feed is a nutritional strategy that allows to partially reduce dietary soybean meal (SBM) inclusions to reduce feed costs, with proven benefits. In addition, reduction of dietary CP leads to a lower dietary electrolyte balance (dEB) due to the concomitant reduction of potassium (K). The aim of the present study is therefore two-fold: 1) to evaluate the potential of reduction of dietary CP until performance drops (1, 2 or 3 % points of reduction) and 2) to combine it with a reduction of dEB (by reducing dietary K) to validate the benefit of reduced dEB/K on litter quality without compromising performance. In total, 9100 male Ross 308 chicks were randomly allotted to 35 pens of 260 broilers. They were fed 5 dietary treatments from 10 to 20d and 20–30d.There was a “positive control” diet (CONTROL; 20.7 % CP in grower, 19.5 % CP in finisher) and 3 levels of dietary CP reduction by 1 % (CP-1 %), 2% (CP-2 %) and 3 % (CP-3 %), all diets formulated to respect at least the ideal AA profile for indispensable AA. In addition, an extra diet called “negative control” (NC CP-3 %) was formulated to have the same ingredient composition as the CP-3 % diet but with lower K and dEB level. Reducing dietary CP as low as 3 % points and maintaining AA and dEB levels resulted in similar or better production performance from 10 to 30d for weight gain, feed intake, feed conversion ratio (FCR) and carcass traits, reduced daily water intake and water-to-feed ratio, excreta N and moisture as well as lower litter moisture and footpad lesions (FPL). Reducing dEB level at − 3 % CP (negative control) increased feed intake and FCR but reduced water intake, water-to-feed ratio, and FPL. It is therefore possible to feed broilers with lower CP diets without compromising performance, with clear benefit on litter quality. As reducing dietary CP is often associated to reduced dietary K, due to lower SBM inclusion, the extent of reduction of K and the control of dEB by Na, Cl and K need to be further explored, especially on litter quality, to facilitate the adoption of low protein diets in practice.