ABSTRACT
In the Nigeria agricultural industry, poultry production is one of the largest sub-sectors which supplies animal protein, vitamins and lipids of high biological value for human consumption. Poultry disease is one of the most important problems faced by the poultry industry and therefore requires great attention. This study was conducted to determine the effects of aqueous extract of Vernonia amygdalina leaf on the performance, blood indices, caecal microbial load and immunodulatory response of broiler birds. One hundred and fifty day old chicks of Abor acre strain of mixed sex were obtained from a reputable hatchery in Ibadan and were raised under the intensive management system using the Completely Randomized Design (CRD). The data collected were feed intake, body weight gain and water intake from day old to the 8th week. Blood samples were collected on the third week for Gumboro analysis, on the 8th week for repeat of the Gumboro analysis as well as for Newcastle Disease analysis and for the determination of haematological and biochemical parameters. Carcass, organ weight and caecal microbial count were evaluated at the end of the experiment. The data obtained were subjected to statistical analysis and significant means were separated using the one way analysis of variance (ANOVA). Birds offered 45g/litre of leaf extract hit a significantly (p<0.05) reduced cost of feeding perhaps due to lower feed intake than the Control. However, similar cost/weight gain recorded for all Treatment implied that Vernonia amygdalina leaf extract did not negatively increase cost of raising broilers to market weight compared with the control. Analysis on the phytochemical content of Vernonia amygdalina leaf extract indicated a significant presence of alkaloids, however saponin, flavonoids and tannin were moderately present while phenol was not detected under screening. Results from the analyzed data showed that feed intake, weight gain and feed conversion ratio were similar (p>0.05) among birds irrespective of the concentration of aqueous extracts of Vernonia amygdalina leaf. However, water intake was reduced among the birds offered Vernonia amygdalina leaf extract (p<0.05). Birds administered 15g/litre of aqueous extracts of Vernonia amygdalina leaf recorded the lowest coliform count while birds in the Control experiment had the highest coliform count. Escherichia coli was highest in the Control treatment while Salmonella growth was seen to be lowest in the Control group as well. Although the general percentage mortality was high across the various treatment. Immune response showed that birds which were administered with 60g/litre of aqueous extracts of Vernonia amygdalina leaf were seen to be at the minimum protective level of birds against the Newcastle Virus. The results from Gumboro showed that birds generally possessed immunity to Gumboro virus both in the 3rd and 8th week of the experiment but with a higher immunity to Gumboro in the 8th week.
Except for blood cholesterol and creatine, all other haematological and biochemical indices were similar (p>0.05) for all treatments. However, the lowest blood cholesterol (60.4mg/dl) was recorded amongst birds offered 45g/litre of aqueous extracts of Vernonia amygdalina leaf. The lowest creatine was recorded amongst the Control birds.
The highest carcass percentage weight (80.1%) was recorded among birds offered 30g/litre of aqueous extract of bitter leaf. Other carcass characteristics as well as organ weights were not significantly affected by water treatment (p>0.05). It was concluded that Vernonia amygdalina leaf extract used up to 60g/ litre of water did not affect the performance of broiler birds, it also conferred partial immunity against Newcastle disease on the birds.
