Effect of Processing on Energy Values, Nutrient and Anti-nutrient Components of Wild Cocoyam [Colocasia esculenta (L.) Schott] Corm

Abstract

Effective utilization of wild cocoyam corm in livestock feed is limited by the presence of anti-nutrient components which requires some forms of processing. The effect of soaking, cooking and fermentation on proximate composition, caloric values and contents of Anti-Nutritional Factors (ANFs) of wild cocoyam [Colocasia esculenta (L.)] Schott corm were determined with the aim of investigating its suitability as a feed ingredient. Raw, Cooked, Soaked and Fermented Wild Cocoyam Corm (i.e. RWCC, CWCC, SWCC and FWCC respectively) were sun dried and their proximate composition, Gross Energy (GE), Metabolizable Energy (ME) and contents of ANFs were determined. Crude protein was significantly (p<0.05) highest in FWCC and significantly (p<0.05) lowest in CWCC. Crude fibre significantly (p<0.05) decreased by the processing methods with the highest values obtained in RWCC and SWCC. Ether extract of RWCC was significantly (p<0.05) higher than for the other processed Wild Cocoyam Corm (WCC). The highest Nitrogen Free Extract (NFE), GE, ME and ME as percentage of GE was obtained in RWCC, FWCC, FWCC and RWCC respectively. Contents of ANFs [tannins, phytate, oxalate, saponin and Hydrocyanide (HCN)] were significantly (p<0.05) reduced by processing methods with RWCC recording the highest value. Fermentation had the highest (p<0.05) percentage reductive values of 42.86, 69.23, 95.05, 73.58 and 57.91% in condensed tannins, hydrolysable tannins, phytate, oxalate and HCN respectively, while the highest (p<0.05) percentage reduction of 48.39% in saponin was obtained in CWCC. There were no activities detected for trypsin inhibitors in all the processed forms of WCC assayed. The results show that the processing techniques adopted significantly (p<0.05) enhanced the nutrients and caloric components and reduced the array of ANFs in RWCC, suggestive of its potential as a feed resource.