[Nutritive value of raw and processed cowpeas]

Area of Science:

• Animal Nutrition
• Food Science and Technology
• Agricultural Chemistry

Context:

• Cowpea (Vigna unguiculata) is a vital legume crop, but its nutritional value can be limited by anti-nutritional factors and processing effects.
• Understanding the impact of different processing methods (autoclave cooking, extrusion) and nutrient supplementation (DL-methionine) is crucial for optimizing its use in animal feed.
• Key nutritional parameters evaluated include available lysine, starch content, trypsin inhibitors, protein efficiency ratio (PER), and various energy metrics (DE, EM, EMn).

Purpose:

• To investigate the effects of autoclave cooking, extrusion, and DL-methionine supplementation on the protein and energy utilization of cowpea.
• To quantify changes in key nutritional components like available lysine, starch, and damaged starch following different processing techniques.
• To assess the impact of processing and supplementation on the protein efficiency ratio (PER) in rats and energy digestibility in animal models.

Summary:

• Autoclave cooking and extrusion reduced available lysine and starch content in cowpeas while eliminating trypsin inhibitors. Damaged starch increased significantly post-processing.
• Protein efficiency ratio (PER) was unaffected by processing but significantly increased with DL-methionine supplementation. Energy digestibility remained consistent across treatments.
• Digestible energy (DE) was higher in extruded cowpea diets compared to cooked cowpea diets. Metabolizable energy (EM and EMn) in chicks was substantially higher for both cooked and extruded cowpeas versus raw cowpeas.

Impact:

• Processing methods like extrusion and cooking can enhance the energy value of cowpeas, making them a more efficient feed ingredient.
• DL-methionine supplementation is a key strategy to improve the protein quality of cowpeas, particularly for monogastric animals.
• These findings provide valuable insights for feed formulators seeking to maximize the nutritional benefits of cowpea-based diets through appropriate processing and supplementation.