Feed nutrient density is
considered as the most critical nutritional factor in poultry commercial
production, not only because it has a beneficial effect on growth performance,
carcass quality, and health of chickens, but also because it in turn affects
the economics of broilers production (Scott, 2002; Sterling et al., 2005;
Brickett et al., 2007; Shai et al., 2013). Because formulation of diets with
high energy and protein sources become increasingly costly, the choice of the
energy and protein density level in practical diets is most frequently based on
economic considerations. Most previous studies were experimented by using
ingredients with high energy and protein content and consequently, most diets
for newly hatched chicks are low in crude fiber (CF). However, current research
implemented in broilers chicken has found that low-fiber diet are detrimental
to the development of the gastrointestinal tract (González-Alvarado et al.,
2008) and that low-fiber diets increase the incidence of enteric disorders
(Montagne et al., 2003).

Optimal nutrient density might
reduce the feed consumption and feed conversion ratio (FCR) of broiler chickens
(Saleh et al., 2004; Shao et al., 2009; Delezie et al., 2010) and to achieve
optimum carcass yield and meat quality of broiler chickens is importantly
corresponding with the balance of energy-to-protein ratio (MacLeod, 1997; Kidd
et al., 2004; Kamran et al., 2008). Mabray and Waldroup (1981) demonstrated
that increasing the dietary energy and amino acid level could significantly
decrease abdominal fat pad size and the degree of fatness of carcasses. Weight
gain and feed gain ratios were significantly better on high-energy diets than
on the low-energy diets at 6, 7, and 8 weeks of age (Holsheimer and
Veerkamp, 1992). 

Using moderate amounts of fiber in broilers feed
might boost growth performance and nutrient digestibility in the starter phase,
primarily when saturated fats have been used (Jiménez et al., 2009). The insertion of fat is typically practiced in modern
broiler industries to increase the energy content of the diet. In addition, the
dietary fat decrease passage rate of the digesta through the gastrointestinal
tract (GIT), accepting for better nutrient utilization (Mateos and Sell, 1980,
1982; Latshaw, 2008). Considering the economic benefits and sustainable of
environmental, the use of low density of energy and crude protein (CP) ratio is
the great interest to reduce feed cost and Nitrogen output to the environment.