Abstract
px; > normal or narrow metabolizable energy to crude protein ratios (ME:CP) on performance,carcass characteristics, body composition and blood parameters in broilers fed from 1 to 42days of age. The chicks were divided into 7 groups. The birds were fed starter & grower diets.Seven experimental diets were formulated in each phase; one control and 6 tested diets. Thecontrol diet was formulated according to the NRC of poultry (1994) and the other six dietsfed three different levels of low energy diets (2900, 2700 & 2500 kcal/kg; one level for each 2groups). The first three tested groups named ''normal calorie-protein ratio” groups in whichthe CP decreased in proportion to the decrease in ME, keeping the normal NRC ratio. In thesecond three tested groups, termed “narrow calorie-protein ratio” groups, the dietaryprotein was kept at the NRC levels leading to ratios narrower than that of the NRC. Resultsshowed that chicks fed low ME diets with normal energy to protein ratio had lower bodyweight and feed utilization efficiency than the chicks fed the control diets. While, birds fedthe low ME diets with normal protein NRC-levels and narrow ratios had nearly equal weightand feed conversion to the control. The body composition and carcass characteristics werenot affected by the dietary treatments. Moreover, the blood parameters had no significantvariations among the groups, except for total protein, ALT and AST which had an increasedresponse to decreased dietary energy density. In conclusion, decreasing the dietary ME levelwithout decreasing the crude protein level was more efficient economically and had no anyadverse effect on the performance. However, decreasing of dietary ME with normal ME:CPratio resulted in decreased performance and low economic efficiency.
Highlights
Global poultry production has been significantly improved over the past fifty years to accommodate rising request
The current findings were in agreement with Hidalgo et al (2004), Waldroup et al (2005) and Kamran et al (2008 a, b) who found that weight gain was decreased as dietary protein and energy decreased
Decreasing the energy and keeping the ratio at its normal NRC level causes a weight decrease and leaving the protein percentage at its NRC level has no effect on body weight
Summary
Global poultry production has been significantly improved over the past fifty years to accommodate rising request. Broilers make up a large part of the industry with chicken meat representing 86% of the world poultry meat production (Economic Research Service/USDA, 2001). New challenges to the industry as the slowing of production and increasing feed and energy costs have led to increases in marketing price for poultry products which are more closely following increases in food price (MacDonald, 2010). Meeting the nutritional requirements for broilers constitutes the majority of costs in poultry production (May et al, 1998). Cost of the feed reaches about 70% of the total cost of production in most poultry production initiatives (Kamran et al, 2010), and certainly is becoming a matter of even greater significance as the prices of feed ingredients continue to increase
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