ABSTRACT

The chemical and nutritional value of baobab (Adansonia digitata) seed as an alternative protein source to broiler chickens was investigated. First, the proximate, mineral, gross energy and anti-nutritional factors (ANF) contents of both raw and processed (boiling, Soaking, Soaked and Boiled, toasting and sprouting) baobab seeds were determined. Processing ofraw seeds was carried out as follows: toasting of the seeds for Ihr, boiling for Ihr with change of water after every 20 minutes, soaking in fresh water for 24hrs, soaking of seeds in a fresh water for 24hrs thereafter boiled for Ihr without changing water, while sprouting was carried out for 6 days of germination of baobab seed with daily change of water. All processed seeds except toasting were oven dried and all processed seeds and raw seeds were milled. Subsequently, bioavailable energy of the raw and processed baobab seed was assessed, using both starter and roaster broilers. Thereafter, tolerance level of raw baobab seed meal was determined using graded levels of dietary inclusion of raw baobab seed meal at 0%, 5%, 10%, 15% and 20%.Furthermore, the effect of different processing methods on the nutritive value ofthe seed was determined, and the best locally adaptable processing method was selected for the next experiment. This involved the determination of the optimal level of quantitative replacement of soyabeans with baobab seed meals. Growth performance, carcass characteristics, organ weight, percentage mortality, haematological indices, blood chemistry parameters and gross margin were evaluated both at starter and finisher phases. Processing of raw baobab seeds caused significant (p<0.05) reduction in crude protein, minerals and anti-nutritional factors. Boiling resulted to the highest percentage reduction of tannin (65.00%), oxalate (33.87%), hydrocyanic acid (46.00%), phytic acid (64.57%) and trypsin inhibitors (37.91%).Boiling also gave the highest values for True Metabolisable Energy (TME), True Metabolisable Energy corrected to nitrogen (TMEn), Apparent Metabolisable Energy (AME) and Apparent Metabolisable Energy correct to nitrogen (AMEn) at both starter and finisher phases. At both the starter and finisher phases, birds fed the 0%, 5% and 10% inclusion levels of raw baobab seed were similar (p>0.05) in growth rate, but those fed the 15% and 20% inclusion levels suffered significant reduction (p>0.05). Most haematological indices of birds fed 0%, 5% andl0% levels of inclusion of raw baobab diets fell within the normal range while birds fed 15% and 20% levels of inclusion of raw baobab seed meal fell below the normal range. Percentage mortality was high in birds fed 15% and 20% level of inclusion of raw baobab seed meal, both at starter and finisher phases. 10% inclusion of baobab seed was therefore adopted for use in the next stage. Results from feeding broilers diets containing 10% levels of RBSM, TBSM, BBSM, SBSM, SBBSM or SPBSM showed that birds fed the boiled meal (BBSM) were highest in growth rate and lowest in feed conversion ratio (P>0.05). Growth performance parameters and gross margin decreased with increasing level of replacement of soybeans with boiled baobab seed meal. No mortality was recorded at both starter and finisher phases. Dressed percentage, breast and back weights decreased (p<0.05) as the inclusion level increased while heart and gizzard weights increased as the inclusion level increased at the starter phase. The decreases or increases were not significant at finisher phase. Elaematological indices except PCV fell within the normal range, though values obtained at the finisher phase were slightly higher than what was obtained at starter phase. The values of total protein, albumin, globulin, SGOT and SGPT decreased with increasing level of replacement both at starter and finisher phases while creatinine, urea and alkaline phosphatase increased with increasing level of replacement of BBSM. In conclusion, boiling emerged the best locally adaptable processing method for baobab seed meal for use at starter and finisher phases in broiler production.