Comparative Antibacterial Efficacies of Four Natural Spices Used as Growth Enhancers in Cockerel Production in Northern Ghana

Abstract

This study evaluated the effects of four natural spices used as dietary additives on selected gut microbial populations in cockerels. A total of 126 Isa Brown cockerels, aged 8 weeks, were assigned to seven dietary treatments in a completely randomised design, with three replicates per treatment and six birds per replicate. The treatments comprised a control diet without spice supplementation and diets supplemented with 2 g/kg feed of black pepper, Negro pepper, black pepper plus Negro pepper, African nutmeg, clove, or African nutmeg plus clove. The feeding trial lasted 8 weeks. At 16 weeks of age, one bird from each replicate was selected for microbial assessment. Caecal samples were collected aseptically and cultured using Salmonella-Shigella agar for Salmonella spp. and Shigella spp., and De Man Rogosa Sharpe agar for Lactobacillus spp. Microbial counts were expressed as log colony-forming units and analysed using one-way analysis of variance. Dietary supplementation significantly affected Salmonella spp., Shigella spp. and Lactobacillus spp. counts. The control group recorded higher Salmonella and Shigella counts than the supplemented groups. Among the tested additives, clove recorded the lowest Salmonella count, while African nutmeg recorded the lowest Shigella count. For Lactobacillus spp., the control and Negro pepper groups recorded higher counts than the other supplemented groups, whereas black pepper and clove showed complete inhibition in the reported results. The findings indicate that the tested spices influenced caecal microbial populations in cockerels, with variable effects on pathogenic and beneficial bacteria. Although the spices showed potential for reducing Salmonella spp. and Shigella spp., their inhibitory effects on Lactobacillus spp. suggest that their use as feed additives should be considered cautiously and requires further evaluation.