Response of broiler finishers to diets containing graded levels of processed castor oil bean (Ricinus communis L) meal

Abstract

A 4-week feeding experiment was conducted to determine the effects of graded levels of dehulled and cooked castor oil bean (Ricinus communis L) meal on the performance of broiler finishers. Castor oil bean seeds were dehulled and detoxified by cooking in two stages at 100 degrees C for 50 min per cooking. Sixty 6-week-old broiler birds (Anak strain) were randomly divided into four groups of 15 birds each. The groups were fed four isocaloric (2.90 Mcal of metabolizable energy/kg) and isonitrogenous (21% crude protein) diets containing 0%, 10%, 15% and 20% dehulled and cooked castor oil bean meal (CBM) for 4 weeks. Results showed that there were significant (p < 0.05) differences among treatments in average daily feed intake, final body weight, average daily weight gain (ADWG), feed conversion ratio (FCR) and protein efficiency ratio (PER). Birds fed diets containing 0% and 10% CBM had significantly (p < 0.05) higher feed intake than birds on 15% and 20% CBM diets. The lowest feed intake was recorded at the 20% CBM inclusion level. The highest ADWG was observed in birds fed 0% CBM diet, but this was not significantly (p > 0.05) different from the ADWG of birds on 10% CBM diet. Birds fed diets containing10% and 15% levels of CBM had similar and non-significant (p > 0.05) ADWG. Birds fed 20% CBM diet had the least (p < 0.05) ADWG. Birds fed 0%, 10% and 15% CBM diets had similar FCR and this was significantly (p < 0.05) lower and better than that of birds on 20% CBM diet. The least (p < 0.05) PER was observed in birds fed 20% CBM diet. Birds fed 20% CBM diet had significantly (p < 0.05) higher packed cell volume (PCV) than birds on 10% and 15% CBM diets. Birds fed 0%, 10% and 15% CBM diets had similar (p > 0.05) PCV values. Birds fed diets containing 0%, 10% and 15% levels of CBM had similar and significantly (p < 0.05) lower heamoglobin than birds fed 20% CBM diets. There were also significant (p < 0.05) differences among treatments in dry matter (DM), nitrogen, ether extract (EE) and nitrogen-free extract (NFE) retention. Birds fed 0% CBM diet had significantly (p < 0.05) higher retention of DM, nitrogen and NFE than birds on 10%, 15% and 20% CBM diets. Birds fed 10% CBM diet had significantly (p < 0.05) higher DM, nitrogen and NFE retention than birds on 15% and 20% CBM diets. The lowest retention of DM, nitrogen and NFE was recorded at the 20% CBM inclusion level. Birds fed 0% CBM diet had significantly (p < 0.05) higher EE retention than birds on 15% and 20% CBM diets. The lowest EE retention was observed at the 20% CBM inclusion level. The results of the study indicate that up to 10% dehulled and cooked CBM can be included in broiler finisher rations for optimum performance.