Response of Dietary Crude Protein Reduction to Different Grain Types in Terms of Production Performance, Nutrient Digestibility and Blood Biochemical Attributes in Broiler Chicken

Poultry nutritionists strive to reduce the dietary crude protein for broilers without affecting their performance because of their environmental and economic benefits. Most of this work is being done on maize-based diets. This study was envisaged to examine the comparative response of crude protein reduction to maize and broken-rice based broiler diets. The 3 x 2 (3 crude protein levels i.e. high, medium and low; 2 grains i.e. maize and broken-rice) factorial arrangement of six treatment diets was offered to 360 broiler chicks from day 1 to 35, where each treatment had 6 replicates (10 birds/replicate). The crude protein had a difference of 1.5% between them i.e. starter (1-21 days) and finisher (22-35 days) had 20.5, 19, 17.5% and 19, 17.5, 16% crude protein, respectively. Body weight and feed intake were unaffected by grain source for the first 21 (P>0.05) days but were higher for maize as compared to broken-rice during 22-35 days and overall experimental period (P<0.05). Weight gain and feed intake decreased while feed conversion ratio worsened with the reduction in crude protein during all the stages of experiment (P<0.05), except feed intake and feed conversion ratio for 1-21 days where the changes were non-significant (P>0.05). Crude protein levels or grain source didn't affect the dry matter and crude fat digestibility (P>0.05) except maize showing better dry matter digestibility than broken-rice (P<0.05). There was no interaction between crude protein level and grain source for any of the parameters (P>0.05) except crude protein digestibility where replacement of maize with brokenrice worsened the already poor crude protein digestibilitpay caused by dietary crude protein reduction (P<0.05). Replacement of maize with broken-rice significantly increased glucose, total cholesterol, high-density lipoprotein (P<0.05). While reducing the dietary crude protein increased the serum levels of glucose, total cholesterol, low-density lipoprotein, triglycerides, highdensity lipoprotein and alanine transaminase but decreased the uric acid levels (P<0.05). The present study suggests that although the effect of crude protein reduction on selected parameters is independent of grain source statistically, the overall response of crude protein reduction was poor to broken-rice based diets as compared to maize-based diets.