Thesis Abstract

A 35-day experiment was carried out in a completely randomized design to determine the efficacy of two phytogenic feed additives as veritable alternatives to antibiotics using 320 day-old unsexed commercial Ross 308 broiler chicks. The chicks were randomly divided into four groups of 80 birds each and assigned to four isocaloric (12.60, 13.2 and 13.4 MJ/Kg AMEn) and isonitrogenous (25.0, 22.5 and 20.07 % CP levels) diets designated as follows diet 1- maize-soybean based diet without additives (negative control), diet 2- maize-soybean based diet containing 10% tylosin (positive control), diet 3-maize-soybean based diet containing phytonutrient (product 1) and diet 4-maize-soybean based diet containing phytonutrient (product 2). Diet 2 contained 200g/ton of antibiotics, while diets 3 and 4 contained 1L/ton each of phytogenic feed additives. Each treatment was replicated 8 times with 10 birds per replicate. Birds had adlib access to feed and water. At 35th day of the experiment, 8 birds per treatment, one from each replicate pens were randomly selected, electrically stunned at 70V and killed by cervical dislocation for meat quality, carcass and organ weights determinations. The birds had their left and right tibias removed for bone strength and mineral assessment. Eight birds per treatment were also randomly selected and euthanized according to standard ethical procedures and used for assessment of haematological parameters. Inclusion of phytogenic feed additives (products 1 and 2) resulted in significant reduction (p<0.05) in feed intake and significantly (p<0.05) enhanced performance of birds at week 7 of the trial. Birds fed diets containing phytogenic feed additives product 2 had significantly higher (p<0.05) thigh weights. The inclusion of phytogenic feed additives (products 1 and 2) in some of the diets reduced fat content of meat significantly (p<0.05) compared to the control groups. Treatments did not have significant (p >0.05) effect on bone parameters. Dietary inclusion of phytogenic feed additives (products 1 and 2) significantly improprved broiler feed efficiency in week 1, reduced broiler meat fat content and improved the immune status of broiler birds. Treatments had no significant (p >0.05) effect on white blood cells (WBC), neutrophils, eosinophil, red blood cells (RBC), haemoglobin concentration (Hb), haematocrit value (HCT), mean corpuscular value (MCV), mean heamoglobin count (MCH), mean cell haemaglobin concentration (MCHC), red blood cell distribution width (RDW) and platelet count. Leucocyte differential values such as lymphocytes, monocytes and basophils were significantly (p<0.05) affected by treatments.

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