Use of Non-antibiotic Growth Promoters in Chicken Broiler Production in Kenya

Abstract

This study was done to investigate the viability of organic acids as alternative replacement to an-tibiotics as growth promoters and in managing broiler chickens in poultry farms around Nairobi in Kenya. The objectives of the study were to (i) Assess the types and levels of antibiotics used in chicken broiler feeds and in the management of the birds; To compare the performance of chicken broilers fed on di-ets containing antibiotic growth promoters with those on a mixture of organic acids; (ii) Evaluate the effects of antibiotics and organic acids on gut morphology and microflo-ra in chicken broilers and (iii) Compare performance of chicken broilers given drinking water containing organic acids with chicken broilers in which no organic acids are added in their drinking wa-ter. The first part of this study was a survey and second part consisted of two feeding trials. The sur-vey was conducted in the environs of Nairobi to determine the extent of antibiotic usage as a therapeutic agent and as a growth promoter. Structured questionnaires were administered to feed millers, agrovets and farmers. It was found that all the agrovets in the study area stocked antibi-otics for use as therapeutic agent and as growth promoters. Both the feed millers and the agrovets were found to be in possession of antibiotics with components similar to those used in human treatment. It was found that only 28% of the 181 farmers interviewed observed antibiotic with-drawal period. This suggests that there is no proper management in the use of antibiotics in the study area, and the eminent risk of selecting resistant bacteria is not dealt with. Feeds for com-mercial poultry production are compounded with antibiotics such as salinomycin sodium and virginiamycin so as to promote growth and reduce mortality. Farmers routinely use antibiotics to control or treat some of the common diseases encountered in their flocks. There is worldwide concern about use of these substances in intensive livestock production because of deleterious effects these substances can have on human health due to consumption of animal food products containing antibiotic residues. Thus the need to identify suitable substitutes to antibiotics for use in poultry industry in Kenya. In the second part of the study, two feeding trials were done. The first feeding trial assessed the performance of chicken broilers fed on diets supplemented with AGP or OA. The second feeding trial assessed the performance of chicken broilers fed on AGP or OA supplemented diets with OA added to their drinking water. For the two feeding trials the diets were formulated to contain 2650 kcal/kg ME and 220g CP per kg in the starter diet and 2750 kcal ME and 180 g CP per kg in the finisher diet. Other nutrients were maintained at calcium 10g per kg, available phospho-rous 4.5g per kg, lysine at 5% of CP and methionine at 2% of CP. The first trial had four treat-ments each replicated six times with 10 birds per replicate. The treatments were: T1 (control with no antibiotic, no organic acid), T2 (Salinomycin sodium), T3 (Acidomix) and T4 (Avimatrix). Salinomycin, Acidomix and Avimatrix were added at rates of 0.05, 0.3 and 0.05% respectively. The diets for trial two were similar to trial one except for addition of organic acid to their drink-ing water, having seven replicates with 10 birds per replicate. The treatments for trial two were: T1 (Activate only), T2 (Salinomycin + Activate), T3 (Acidomix + Activate) and T4 (Avimatrix + Activate). Activate was administered at the rate of 0.3 ml per litre of drinking water from Day 3 – 16 and Day 30 – 44. Feed intake were recorded daily and live weight weekly and Feed con-version ratio and weight gain calculated weekly. Jejunal samples were obtained on days 23 and 44 for histology and microbiology. Blood was collected for serology. There were no significant differences observed in feed intake, average daily gain, final body weights and feed conversion ratios between antibiotic and organic acid diets (p<0.05), Addition of organic acid to drinking water led to 9% improvement in feed conversion ratio from average of 2.66 to 2.42 and a 96% reduction total bacterial count from antibiotic, 25% increase from unprotected acid and 397% increase from protected acid dietary treatments. Protected organic acid treatments had signifi-cantly higher lactobacilli and yeast count, 92.86 x 105 cfu compared to 3.5 x 105 cfu for antibi-otic treatment, no coliforms were isolated in unprotected organic acid compared to 0.287x 105 cfu for antibiotic treatment. Antibiotic treatment had significantly taller villi, 1722μ compared to 1449 μ for protected organ-ic acids (p<0.05). Inclusion of organic acid into the drinking water increased villi height for all the treatments except unprotected organic acid treatment. Organic acid treatments had broader villi, 117.1μ (protected) and 155μ (unprotected) compared to 138μ (antibiotic) and 108.4μ (con-trol). Addition of organic acid to drinking water increased villi bread for both control and antibi-otic. Tunic thickness and glandular area thickness were all significantly improved in treatments without inclusion of organic acid in the drinking water. Generally, inclusion of organic acid in broiler’s drinking water, improved feed conversion ratio and gave a better gut health through in-crease in beneficial bacteria and reduction in coliform counts. Organic acids are viable alterna-tives for antibiotics in ensuring improved health and productivity of chicken broilers.