Proximate analysis of nutrients and in vitro radical scavenging efficacy in selected medicinal plant powders with potential for use as poultry feed additives

Abstract

The use of antibiotic feed additives in poultry feed is currently discouraged owing to the development of antibiotic-resistant bacteria and other drawbacks. The benefits and importance of phytogenic feed additives as potential alternatives in poultry nutrition include stimulation of digestion, higher feed conversion rate, reduced incidence of disease and profitability. Evaluation of the mineral content and other properties of plant material generates useful information towards rationalizing the use of plants as alternatives to antibiotic feed additives. Concentrations of macro-and micro-minerals in Morinda lucida, Acalypha wilkesiana, Ficus exasperata and standard broiler feed were determined using ICP-MS, and ICP-OES. Levels of degradation of C and N over specific periods of time were evaluated by dry oxidation (Dumas). Radical scavenging activities were investigated using DPPH and ABTS assays while levels of phytochemical constituents were assessed using standard methods. Macro- and micronutrient concentrations in the plant powders were generally higher than those of standard broiler feed. With few exceptions it was observed that the levels of total C and N as well as the C/N ratio in plant powders and standard feed were proportional to storage time. Macronutrients were higher in F. exasperata and A. wilkesiana while micronutrients were higher in A. wilkesiana and M. lucida. The highest total N and C levels were observed in M. lucida while A. wilkesiana showed the highest C/N ratio. Remarkable radical scavenging activities were displayed by A. wilkesiana while the highest total phenolic content (TPC) and total flavonoid content (TFC) were exhibited by aqueous and acetone extracts of F. exasperata respectively. High antioxidant activity was correlated with high total C and C/N ratio of the plant powders. In M. lucida leaf powder, fructose was the dominant sugar at 8,450 mg/kg DW followed by glucose and sucrose with a good amount of Se at 0.32 mg/kg DW. The contents of malic acid were the highest (20,500 mg/kg DW). Organic acids decrease intestinal Escherichia coli and Salmonella species in broilers. Cl− was the most predominant anion. Minerals and organic acids are essential antimicrobial and antioxidant constituents of poultry diets for the maintenance of gut flora health, and their body metabolic, enzymatic and antioxidant defence. This study highlights the nutrients content of the selected plants, providing motivation for further investigation of these species as poultry feed additives.