Cassava (Manihot Esculanta Crantz): A Source Of Energy In Diets For Broiler Chickens

ABSTRACT Three experiments were conducted to evaluate cassava, a tropical root crop, as a source of energy in diets containing all vegetable protein or 5% fish meal which is a source of readily available essential amino acids required by growing chicks. The biological metabolizable energy (ME) was determined replacing part of the basal diet with the test materials (cassava meal Grades I and II combined and Grade III. Grades I and II have little of the rind and outer cover whereas Grade III contained more of the rind and outer cover.) The M E 's were corrected for the nitrogen retained and the values with their standard errors obtained for Grades I and II combined were 3.59 Kcal/g ± 0.03 and those for Grade III were 3.20 Kcal/g + 0.04. The diets for the second and third experiments were formulated with the help of the computer to determine quantities of ingredients to provide various nutrients within given limits and specification. (Cassava meal was given a very low value so that maximum levels of 0, 20, 30 and 401 would be included in the diet. Two sets of four diets were formulated with or without 5% fish meal.) During the first four weeks the weight gains of birds on the 51 fish meal diets peaked at 20% cassava meal while those on no fish meal showed a depression with 20% cassava meal. Generally those on 5% fish meal produced better weight gains than those on diets without fish meal. Surprisingly the birds on the latter diets outgained the former ones during the second four weeks. By the end of the eight week period even though birds on diets without fish meal were slightly heavier these differences were not large enough to be detected statistically. It may be concluded from the study that the broiler chick benefits from the readily available essential amino acids in the fish meal during the early stages of growth but later its benefit is not apparent. Data on feed intake during the first four weeks show that as the level of cassava meal increased in the diets without fish meal the amount consumed decreased, but with diets that contained fish meal the feed intake increased with increase in the level of cassava meal. Similar quantities of the 0 and 51 fish meal diets were consumed during the second four weeks and the differences observed were deemed to be due to chance variation. This was also reflected in the feed intake to eight weeks. On a practical basis, the poultry farmer is interested in the response of an animal when given a specified amount of feed and therefore predicted values were computed. The equation Y = a+b1X 1+b2X2+b3X 3+b4X4+b5X5 , where X^ is the level of fish meal X2 is the level of cassava meal X^ is the level of cassava meal squared by fish meal X^ is the level of cassava meal squared and X,- is the amount of feed intake was used to predict the response in weight gains. The diets for the third experiment were pelleted and then crumbled and fed to broiler male chicks. It was o b ­ served that the differences in weight gains in response to the various levels of cassava meal in the diets were due to chance variation and it may therefore be concluded that cassava meal could be successfully included in broiler chick diets. However, one should ensure an adequate level of sulfur amino acids to help counter any hydrocyanic acid activity that may be present in the diets. Also the diets should be properly balanced.