Microbial transformation of crop residues into a nutritionally enriched substrate and its potential application in livestock feed

Abstract

Bioconversion of three different agro-residues (groundnut shells, pigeon pea husk and wheat straw) was studied using endophytic fungi with a view to increasing the nutritive value and to evaluate its feasibility as poultry feed. An endophytic fungal isolate obtained from Celastrus paniculatus, effectively biotransformed selected agro-residues in solid state fermentation. After 21 days incubation, isolate CPL-1significantly altered the nutritional values of all tested agro-residues. Cellulose, hemicellulose, and lignin content were significantly reduced (P < 0.05) whereas, total carbohydrates were significantly increased in the biotransformed waste as compared to untreated residues. Of the three agro-residues studied, the groundnut shells were found to have maximum carbohydrate content (13.92 ± 0.7 g/100 g) after the treatment. Similarly, the total crude protein and total nitrogen contents of the treated waste were also significantly improved (P < 0.05) as a function of treatment with the isolate CPL-1 with their highest contents (24.95 ± 1.4 and 15.53 ± 1.2 g/100 g, respectively) recorded in the treated groundnut shells. The isolate CPL-1 was identified as Colletotrichum spp. based on the morphology. The tannins and phytate contents were found to be significantly lower (P < 0.05) in the processed wastes. Application of treated agro-residues in poultry diets revealed that the biotransformed groundnut shells and pigeon pea waste can be added up to 20 and 10%, respectively to the commercial poultry diet used in the study without any adverse effects. The results showed that the treated residues of groundnut shells can be used as a partial substitute to the conventional poultry diets as they are rich in enzyme phytase and other nutrients and have good digestibility.