Standardised Ileal Amino Acid Digestibility of Processed Senna Seed (Senna occidentalis L.) in Broiler Chickens

Abstract

Senna seed is an underutilised tropical legume with potential as an alternative protein source in poultry nutrition. However, its utilisation in broiler diets is constrained by anti-nutritional factors that reduce amino acid availability and utilisation. Processing methods have been reported to improve nutrient availability through the reduction of these antinutrients. This study evaluated the standardised ileal amino acid digestibility of processed senna seed meal in broiler chickens.

One hundred and sixty 17-day-old Ross 308 broiler chicks were randomly assigned to four dietary treatments with five replicates of eight birds each in a completely randomised design. Diet 1 was a highly digestible protein (HDP); a control and diets 2, 3 and 4 contained Raw Senna Seed Meal (RSSM), Fermented Senna Seed Meal (FSSM), and Boiled Senna Seed Meal (BSSM) supplemented diets. Amino acid composition of the test ingredients was determined using standard analytical procedures, and ileal digesta were collected on day 21 for digestibility assay. Data were analysed using ANOVA at p = 0.05.

Results showed that processing significantly affected (p < 0.05) the amino acid composition and standardised ileal amino acid digestibility of Senna occidentalis seed meal. Among the senna seed meals, RSSM generally contained higher amino acid concentrations. However, standardised ileal amino acid digestibility was highest in birds fed HDP followed by FSSM and BSSM diets. In FSSM, leucine (74.53%), lysine (70.52%), threonine (66.25%) and tryptophan (79.58%) showed superior digestibility compared to the RSSM diet (57.70%, 53.06% and 66.68%), respectively.  This indicates that fermentation enhanced amino acid bio-availability through microbial degradation of anti-nutritional factors. 

In conclusion, fermentation effectively improved the nutritive value of Senna seeds by reducing anti-nutritional factors and enhancing amino acid digestibility and utilisation. Therefore, properly processed senna seed meal at 10% inclusion level can serve as a promising alternative protein source for broiler chickens.