Phytochemical composition of Capsicum frutescens and its effect on growth, carcass, organoleptic and feed cost parameters of indigenous and broiler chickens
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Chicken meat is a major source of animal protein and its production has increased globally by 25% in the last decade mostly in Asia and Africa. However, due to the ever-increasing problem of antibiotic resistance, routine non-therapeutic antimicrobial use in chicken production systems is no longer considered a reasonable and viable practice. Natural products are among the preferred replacers of antibiotics for non-therapeutic uses such as promoting growth. In addition, the chicken meat produced from systems utilizing natural products is considered safer and protective of consumer health. Herbs and spices are important sources of natural products that can be used to improve growth and carcass traits of chickens in Uganda. Capsicum frutescens is among the common spices easily accessible but its use as an enhancer of growth and carcass traits in intensive chicken production systems has not yet been investigated in Uganda. This study aimed at establishing phytochemical composition and identification of dietary inclusion levels of Capsicum frutescens powder with positive effects on growth, carcass and organoleptic parameters of indigenous chickens and on growth and carcass traits of broilers. The phytochemical composition and antioxidant activity of C. frutescens powder were determined using conventional methods. A completely randomized design was used for each of three experiments for broilers and for each of the two experiments for indigenous chickens. The three experiments on broilers were differentiated by the durations of feeding diets enriched with C. frutescens. The three durations were: 13 days, 19 days and 24 days. Each duration represented the number of days prior to 59 days of age which was the age of slaughter. In each broiler experiment, three treatments defined by three dietary inclusion levels (1.1%, 2.2%, 4.4%) of C. frutescens powder were each randomly assigned to a group of forty-five broilers housed in three pens with each pen consisting of fifteen broilers. In addition, each experiment had a control group with forty-five broilers housed in three pens with each pen consisting of fifteen broilers. The control group received only the basal finisher diet. For the indigenous chickens, one of the experiments utilised cotton seed cake as the lipid source whereas sunflower seed cake was the source of lipids in the other. In the experiment where cotton seed cake was utilised, three treatments defined by inclusion levels (1.1%, 2.2%, 4.4%) of C. frutescens powder in diets, were each randomly assigned to a group of forty-five chickens housed in three pens with each pen consisting of fifteen chickens. The control group of this experiment had forty-five chickens housed in three pens with each pen consisting of fifteen chickens. The control group received only the basal diet. The other experiment of the indigenous chickens, where sunflower seed cake was utilised as lipid source, had two replicates instead of three and the treatments as well as number of chickens per replicate were similar to that earlier described for indigenous chickens. In both experiments of indigenous chickens, the chickens were aged 199 days at the start of the experiment and the duration of the experiment was 37 days. Results indicated that C. frutescens powder has several phytochemicals including alkaloids, coumarins, saponins, anthracenosides and reducing compounds. In addition, the total phenolic content, alkaloids and saponins were 587.75 mg GAE/100g, 6.8% and 23.5%, respectively. Further, the antioxidant activity scores based on DPPH radical scavenging activity at concentrations 100, 200, 400, and 500 ug/mL were 17.08, 20.75, 29.82, and 33.31%, respectively. Among broilers, diets formulated with 2.2% inclusion level and provided for 19 days had positive effects represented by significant increase in final body weight (1257.50±26.40g, P=0.007), carcass weight (786.18±22.39g, P=0.006) and gizzard weight (33.37±1.23g, P=0.02) by 14%, 15% and 12%, respectively relative to the control. Similarly, among indigenous chickens, diets with sunflower seed cake formulated with 2.2% inclusion level had positive effects demonstrated by significant increase in heart weight (4.00±0.33g, P=0.001), liver weight (15.30±0.80, P=0.04), proventriculus weight (4.25±0.14g, P=0.004) and intestine weight (82.50±3.58g, P=0.002) by 38%, 15%, 25%, and 21% respectively. Further, the 1.1% inclusion level increased intestine weight (68.00±2.17g, P=0.0002) by 26% whereas 4.4% inclusion level increased heart weight (3.60±0.21g, P=0.04) by 24% among indigenous chickens fed diets with sunflower seed cake. In contrast, the 4.4% inclusion level significantly decreased the body weight (912.50±32.05g, P=0.01), carcass weight (592.30±23.43g, P=0.04) and intestine weight (65.83±1.94g, P=0.001) by 12%, 10%, and 17% respectively among indigenous chickens on diets with cotton seed cake. Further, the 1.1% inclusion level decreased the liver weight (13.27±0.66g, P=0.02) by 14% whereas the 2.2% inclusion level decreased the heart weight (2.97±0.18g, P=0.001) by 19% among indigenous chickens on diets with cotton seed cake. Furthermore, results showed that none of the inclusion levels of C. frutescens had an effect on texture, taste, juiciness and overall acceptability of meat from indigenous chickens. The results of this study highlight that C. frutescens has several beneficial phytochemical compounds and high antioxidant activity for improving broiler growth and carcass yield. Further, an inclusion level of 2.2% in finisher diets for 19 days is acceptable since it has capacity to improve final body weight and carcass weight of broilers by 14% and 15% respectively relative to the control. Similarly, an inclusion level of 2.2% in diets with sunflower seed cake is recommended for indigenous chicken effective 199 days of age due to potential to improve carcass yield.