Daniellia oliveri Leaf Extracts as an Alternative to Antibiotic Feed Additives in Broiler Chicken Diets: Meat Quality and Fatty Acid Composition

The objective of the study was to examine the effect of feeding different levels of Daniellia oliveri leaf extract (DOFE) on the meat quality and fatty acid composition of broiler chicks. A total of 375 one –day old broiler chicks were randomly assigned into five dietary treatments of seventy-five birds per group; each group was further divided into 5 replicates consisting of 15 chicks each. The dietary treatments include a control diet-fed 1.25 g/litre Oxytetracycline (T1), T2, T3, T4 and T5 were fed DOFE at 20 ml, 40ml, 60ml and 80 ml/liter respectively. Basal diet was formulated to meet the nutritional requirements of birds according to NRC (1994), feed and water were given ad libitum and the experiment lasted for 56 days. Result obtained showed that Daniellia oliveri leaf contained Dry matter (89.11%), crude protein (18.95%), crude fibre (13.11%), ether extract (4.78%), ash (6.10%), neutral detergent fibre (28.10%), and acid detergent fibre (47.50%).  Significant differences (P<0.05) were observed in the proximate composition of the breast meat. Total saturated fatty acid (TSFA), total unsaturated fatty acid (TUFA), and omega-6/omega -3 ratio (n-6: n-3) values were significantly influenced (P<0.05) by DOFE. Birds in T5 had the highest TUFA value of 77.87 % followed by T4 (72.45%), T3 (66.43%), T2 (61.94 %), and T1 (41.47%) respectively. While T1 (44.71%) had the highest value of TSFA (P<0.05) relative to other treatments. The atherogenic index was significantly (P<0.05) different among the treatments, the value increases as the level of DOFE increased. It was concluded that feeding DOFE to birds at 80 ml/liter highly influenced the composition of fatty acid and meat quality of animals without any negative effect on their general performance.


INTRODUCTION
The huge increase in poultry production to meet growing demand in the world has led to the rise in antibiotic use, leading to a worrying increase in cases of antibiotic resistance diagnosed in animals and humans via direct contact, environmental contamination, and feed consumption causing high cases in various ailments including cancer (Alagbe, 2020). Poultry meat is an excellent source of high protein, essential vitamins, minerals, and fatty acids especially polyunsaturated fatty acids (Muhammad et al., 2015; Akintayo and Alagbe, 2020; . Consumption of antibiotics contaminated animal products is injurious to health while multiplications of antibiotic resistance pose a great threat and danger to the livestock industry, particularly poultry production and venture in Nigeria Samarasinghe and Wenk, 2002;Ahsan et al., 2018). It thus becomes imperative to find cheap, readily available alternatives to antibiotics feed additives in poultry diets. Among the potential alternative is the use of medicinal plants.
In view of these abundant potentials, the use of Daniellia oliveri leaf extract will promote food safety. Therefore this study was carried out to examine the effects of Daniellia oliveri leaf extracts as an alternative to antibiotic feed additives in broiler chicken diets: meat quality and fatty acid composition.

METHODS
The experiment was carried out at the University of Abuja Teaching and Research Farm, Gwagwalada, Nigeria. Mature leaves of Daniellia oliveri leaves were collected from different plants within the University premises; it was authenticated at the herbarium of the Department of Crop Science, University of Abuja, Nigeria, with a voucher number CS -012 D. The leaves were washed and allowed to dry under shade until a constant weight was obtained and made into a powder using a Panasonic electric blender Model (AA-7301A) and stored in a well-labeled air-tight container. 200 g of the sample was soaked in 1000 ml of ethyl alcohol (80 % BDH), the mixture was agitated using an electric blender, poured in a container, and then kept in the refrigerator at 4 o C for 48 hours, sieved with What Man No 1 filter paper to obtain Daniellia oliveri leaf extracts (DOFE).

Animals and Their Management
Three hundred and seventy-five one-day-old (Ross 308) broiler chicks of mixed sex were used for the experiment. The birds were purchased from a commercial hatchery in Ibadan, Oyo State, Nigeria, and weighed on arrival on the farm to obtain their initial body weight and thereafter weekly. A deep litter housing system was used, it was fumigated two weeks before the commencement of the study, and the surrounding environment was also cleaned daily to ensure proper hygiene. Birds were divided into five treatments with five replicates of fifteen (15) birds in a completely randomized design. Electric brooders were used and wood shavings serve as the litter material. Vaccines were administered according to the prevailing disease condition in the environment and all other management practices were strictly adhered to throughout the experiment which lasted for 56 days.

Ration Formulation
Three (3) basal diets were formulated at different stages of production to meet up the requirements of birds according to NRC (1994). Broiler starter's mash (0-21 days), growers mash (22-35 days), and finishers mash (36-56 days Proximate compositions of experiment diet and meat (breast and thigh) were determined by using the official method of analysis by AOAC (2000). Weight gain (g) = final weight (FW) -initial weight (IW) Feed intake (g) = Amount of feed consumedremaining feed

Fatty Acid Analysis
At the end of the experiment, five birds were randomly selected from each treatment for fatty acid analysis (FA). Meat lipids (breast) from freezedried; grounded samples were extracted with chloroform-methanol using helium as carrier gas. The column temperature was held at 50°C for 1 min, and then the temperature was raised up to 150°C at the rate of 15°C per min. The temperature was later increased to 175°C at the rate of 2.50°C and hold for 5 min and finally increased to 220°C at the rate of 2.50°C per min and kept for 5 min. The identification of the peaks was made by comparison of the equivalent chain length with those of authentic fatty acid methyl esters. Peak areas were determined automatically using the Agilent gas chromatography chemstation software. The fatty acid concentrations were expressed in percentage of the sum of total identified peaks measured in each sample.

Proximate Composition of Breast Meat
The proximate composition of breast meat is presented in Table 4

CONCLUSION
It was concluded that DOFE contains several bioactive chemicals or phytochemicals which are capable of modification of meat fatty acid composition of animals, these chemicals are safe, effective, cheap, and can also influence the secretion of digestive fluids and total feed intake in animals, thus promoting food safety. Feeding birds' DOFE at 80 ml/liter is safe and does not have any deleterious effect on the general performance of the animal.   Efficacy of dried Phyllantus amarus leaf meal as an herbal feed additive on the growth