A review of limitations to using cassava meal in poultry diets and the potential role of exogenous microbial enzymes

Utilisation of cassava as energy and protein feed resource in broiler chicken and laying hen diets

A detailed understanding of the nutrient contents of cassava products is crucial to fully maximise their utilisation in animal feed. This study aimed to review published data on the nutritional quality of cassava products and their use as a source of energy and protein in broiler chicken and laying hen diets. Cassava is a tuber crop that grows abundantly in tropical countries, and its products are classified as energy or protein feed resources based on their protein and energy levels. Cassava starch residue (CSR), cassava root meal (CRM), cassava peel meal (CPM), ensiled cassava peel meal (ECPM), fermented cassava peel meal (FCPM), cassava pulp, and cassava root sievate meal (CRSM) were classified as an energy source in chicken feed, whereas cassava leaf meal (CLM) is classified as a protein source. Nutritional analysis indicates that cassava leaves are high in protein, fibre, minerals, vitamins (B₁, B₂, and C), and carotenoids, while CRM is rich in energy but low in crude protein (CP). Additionally, cassava contains cyanogenic glycosides, especially linamarin, and lotaustralin, which release toxic hydrogen cyanide (HCN) upon tissue disruption. The utilisation of cassava as an energy or protein feed resource in the chicken diet is limited by its high fibre, presence of HCN, nutrient imbalance, and dusty nature of its dried meals. Efforts have been made to enhance the nutrient quality of cassava and increase their utilisation in chicken feed using different processing techniques with some success. Available information on the nutrient contents of differently processed cassava and its effect on chicken performance is vast and dispersed, making it hard to use such information in the decision-making process. Therefore, this review aimed to aggregate published articles on the nutrient contents of cassava products and their impacts on the health and productive indices of broiler chickens and laying hens into a single document for ease of comparison and decision-making.

Comparative Transcriptome Profiling of Cassava Tuberous Roots in Response to Postharvest Physiological Deterioration

Cassava is one of the most versatile tuberous-root crops on Earth. However, the postharvest storage properties of cassava tuberous root mean that it is perishable through a process known as postharvest physiological deterioration (PPD), which seriously affects its starch quality. Therefore, a comprehensive understanding of the transcriptional regulatory activity of cassava against the PPD response is necessary in order to extract key molecular mechanisms related to PPD tolerance. In this study, we found that RYG1 tuberous roots showed delayed PPD compared to those of SC8. In addition, RYG1 roots maintained a more stable cell wall structure after storage than those of SC8. The transcriptome changes in tuberous roots were analyzed for both RYG1 and SC8 after 21 days of storage (SR and SS) compared to fresh (FR and FS) by the RNA-Seq method. The total number of differentially expressed genes (DEGs) in the various comparisons of these four samples ranged from 68 to 3847. Of these, a total of 2008 co-DEGs in SR vs. SS were shared by either SR vs. FR or SS vs. FS. GO and KEGG enrichment analysis revealed that upregulated co-DEGs in SR vs. SS were mainly enriched in photosynthesis, protein processing, hormone and cutin, suberine and wax biosynthesis. By contrast, the downregulated co-DEGs were mainly related to cell wall organization, starch and sucrose metabolism, galactose metabolism, phenylpropanoid biosynthesis, diterpenoid biosynthesis, cysteine and methionine metabolism and flavonoid biosynthesis. The protein-protein interaction (PPI) networks of the co-DEGs showed a complex interaction of genes in different pathways, and 16 hub genes were characterized to have a degree in excess of 15, among which eight genes were associated with photosynthesis. These results provide new information for the study of cassava resistance to PPD and lay a foundation for the further molecular breeding of storage-tolerant cassava varieties.