Abstract: The present experiment was conducted to investigate the effects of adding graded levels (0, 0.15, 0.45, 0.3 and 0.6%) of garlic (Allium sativum) to the basal experimental diet on the broiler chicks growth performance and immune response. One hundred and fifty unsexed Ross broiler chicks were randomly distributed; 30 birds/dietary treatment and each treatment contained 3 replicates (10 birds/replicate). The results showed significant (p<0.05) improvement in feed conversion ratio of birds fed 0.3% garlic. The mortality rate followed the same trend of feed conversion ratio. Weight gain was found to be increased by inclusion of garlic, but was not statistically significant. Total White Blood Cells (TWBC) of birds fed 0.3% garlic was significantly (p<0.05) higher compared to these fed other dietary treatments and the lower TWBC was recorded by the control treatment. No significant differences in blood serum total protein, albumen and globulin were observed. Colour, flavour, tenderness and juiciness of sensory evaluated samples were not statistically different.
INTRODUCTION
The practice of complementary and alternative medicine is now on the increase in developing countries in response to World Health Organization directives culminating in several pre-clinical and clinical studies that have provided the scientific basis for the efficacy of many plants used in folk medicine to treat infections (Vijaya and Ananthan, 1997; Dilhuydy and Patients, 2003; Iwalokun et al., 2004). Previous studies have demonstrated positive effects of herbal supplements on production performance and carcass quality (Schleicher et al., 1998; Tekeli et al., 2006, 2008).
Garlic, a member of the Allium family (Liliaceae), has been used traditionally for ages to treat a wide array of diseases, namely, respiratory infections, ulcers, diarrhea and skin infections (Fenwick and Hanley, 1985). Reuter et al. (1996) reported garlic as a plant with antibiotic, anticancer, antioxidant, immunomodulatory, anti-inflammatory, hypoglycemic and cardiovascular- protecting effects.
Moreover, garlic is very rich in aromatic oils, which enhance digestion and positively influenced respiratory system being inhaled into air sacs and lungs of birds. Also it was found that garlic has strong antioxidative effects (Gardzielewska et al., 2003).
In pursuit of improved broilers health and in order to fulfill consumer expectation in relation to food quality, poultry producers commonly apply natural feeding supplements, mainly herbs (Gardzielewska et al., 2003). Garlic extract and/or garlic components were able to prevent chemically induced tumors or acute toxic effects of chemicals. The chemo-preventive potential of garlic has been attributed to the presence of several bioactive organosulfur compounds. Theses compounds might act as antioxidants (Fanelli et al., 1998; Siegers et al., 1999). The antioxidative stress properties of garlic might result from the contributions of its sulfur component in different steps and not necessarily from the contribution of only one of them (Fanelli et al., 1998). Garlic also has been shown to have strong antimicrobial action (Iwalokun et al., 2004; Gbenga et al., 2009). Allicin and its derivatives have been shown to be a larvicidal and bacteriostatic, active against both Gram positive or Gram negative organisms as well as fungi such as Candida albicans and viruses including influenza viruses (Chang and Cheong, 2008). Allium sativum taken at a low dose may have some therapeutics potentials against gastric ulcers associated with H. pylori infection (Adeniyi et al., 2006). Garlic extracts do have significant inhibitory effects against microorganisms associated with dental caries Masaadeh et al. (2006). In the present study broiler starter and finisher diets were supplemented with graded levels of garlic to evaluate the effect of garlic supplemented broiler diets on broiler performance, carcass quality and broiler immune response.
MATERIALS AND METHODS
Experimental Site and Duration
The present experiment was conducted in the Poultry Unit of the College
of Veterinary Medicine and Animal Production, Sudan University of Science and
Technology at Hillat Kuku in the period from the 2nd of July to 16th of August
2009.
The Poultry-house and the equipments were cleaned and disinfected before starting the experiment.
Experimental Diets
The basal experimental starter was formulated according to NRC (1994) to meet the broiler requirements Table 1. The finisher formula of broiler requirements was as out lined by the NRC (1994) (Table 2).
Clean pure garlic was bought from local market, prepared by drying in shadow for three days and then ground soft. Chemical composition of garlic is presented in Table 3.
Garlic powder is added to the basal experimental diets in graded levels (00, 0.15, 0.3, 0.45 and 0.6%). Zero level is served as the control treatment.
| Table 1: | Composition and calculated analysis of starter experimental basal diet |
| Table 2: | Composition and calculated analysis of finisher experimental basal diet |
| Table 3: | Chemical composition of garlic |
| Source: Watt and Merrill (1963) | |
Experimental Birds
One hundred and fifty one day old, broiler chicks (Ross) were bought from
Coral Poultry and Feed Production Company Ltd., Khartoum, Sudan. The chicks
fed the control diet for two weeks as adaptation period.
Water and Feed provided ad libitum, light was available 24 h per day. The experimental birds were randomly assigned to the 5 dietary treatments (30 birds/treatment). Each treatment consisted of three replicates (10 birds/replicate).
Methods
Data Collection
At age of 15 days the experimental diets were randomly distributed to the
experimental birds. The starter basal diet was used for two weeks while the
rest of the experimental period the birds fed the finisher diets.
Broiler Performance
At the end the experiment (6 weeks) the chicks had been fasted for 8 h and
then it was weighted to determine the final body weight. Mortality was recorded
when it occurred.
Carcass Preparation or Composition
Hot dressing percentage and cold dressing percentage were determined according
to the equations below:
Sensory Evaluation
The right halves of the carcasses were stored in a deep freezer (-20°C)
for 7 days. Then sensory panel sessions were conducted to determine the effect
of garlic. The right halves of the carcasses from each treatment were thawed
for (24 h) in a refrigerator (4°C) then the breasts, thighs and drumsticks
were wrapped individually in aluminum foil and roasted at (175°C).
They were cut into pieces and served warm. Trays of randomized sample from the main treatment were evaluated at each session by panel of semi trained panelists (Cross et al., 1978).
Panelists were instructed to record their responses for each attributes (Colour, Flavor, Tenderness and Juiciness) on scale in the range 1-8 (8 being rated the most desirable).
Chemical Analysis
Chemical analysis was carried out according to AOAC (1995)
method. Serum total protein, albumin and globulin were determined according
to Watt and Merrill (1963).
Haematology Parameter
Total White Blood Cell Count (TWBC) was carried out according to Sturkie
(1976).
Statistical Analysis and Experimental Design
A complete randomized design was used in this experiment. Collected data
were subjected to analysis of variance and LSD test was used to determine the
significance among treatments means according to Gomez and Gomez
(1984).
RESULTS AND DISCUSSION
Broiler Performance
The results of the effect of feeding graded levels of garlic on the broiler
chick performance (4-6 weeks of age) are shown in Table 4.
Birds fed 0.3% garlic basal diet had significantly (p<0.05) lower total feed
intake (3892 g) compared to the other dietary treatment. This result was reflected
on the feed conversion ratio (2.46) which revealed a significant (p<0.05)
improvement compared to the other dietary treatments.
| Table 4: | Overall performances results affect by feeding garlic |
| Values are means of birds/treatment. Values are Means±SE. Means within columns not sharing common letter (s) are significantly different (p<0.05). * = (p<0.05), NS: No significant different | |
| Table 5: | Effect of feeding garlic on dressing percentage |
| Values are means of 30 birds/treatment. NS: No significant different | |
| Table 6: | Effect of feeding garlic on blood serum constituents |
| Values means of/S sample/treatments. NS: No significant different | |
| Table 7: | Effect of feeding garlic on total white blood cells (TWBC) |
| Values are means of 15 sample/treatment. Values within a row different superscript are significantly different (p<0.05) | |
No mortalities were recorded for birds. No significant changes in the total weight gain were observed but it tended to increase in birds fed higher inclusion rates of garlic 0.3, 0.45 and 0.6%.
Dressing Percentage
No changes were observed in hot and cold dressing percentage among all groups
as shown in Table 5.
Blood Serum Constituents
Total protein concentration was higher in chicks fed 0.3, 0.45 and 0.6%
while albumin showed high values in birds fed 0.3% garlic (Table
6).
Total with Blood Cells
TWBC showed significant differences (p<0.05) among the dietary treated
groups. TWBC was increased by increased addition of garlic level. Birds fed
0.3% garlic revealed higher TWBC compared to other groups (Table
7).
Sensory Evaluation
There were no significant differences among dietary treatments in the tested
characteristics (colour, flavor, tenderness and juiciness) (Table
8).
Garlic (Allium sativum) is uncommonly used as plant supplement in poultry feeds. It was found that it has some positive effects on human and animal health and immune response which reflected in positive effects on the animal performance (Fanelli et al., 1998).
| Table 8: | Sensory characteristics effect by feed garlic |
| Values are means of I5 sample/treatment. Values are points out of 8 points. NS: No significant difference between treatments | |
The results of the present study showed a significant (p<0.05) improvement in feed conversion ratio of birds kept on a diet containing 0.3% garlic. Tekeli et al. (2006) was reported that another plant extract contribution (Z. officinale 120 ppm) such as garlic improved live weight gains and feed conversion ratio of broiler also increased population of intestinal lactic acid bacteria. The improvement in feed conversion ratio might be due to lower (p<0.05) feed intake and improved weight gain livebody. Weight gain tended to improve by inclusion of garlic. These results might be due to the good health status which may be caused by the inclusion of garlic.
It was reported by Birrenkott et al. (2000) that including garlic in the laying hens garlic inclusion resulted in increased TWBC which reflecting good immune response. It was also found that garlic powder decreases external parasites by inhibition of its growth (Barowski and Boyd, 1944). The result of the present study in TWBC was in agreement with that reported by Sumiyoshi (1997) and Oluwole (2001). In addition to that the improved broiler performance might be due to the garlic chemical composition (Reuter, 1995; Sumiyoshi, 1997).
In the present study, the 0.3% inclusion rate of garlic was found to be the best and optimum inclusion rate in growth performance, TWBC, blood serum constituent content which might be due to the optimum Low Density Lipids (LDL) and low density cholesterol caused by garlic inclusion as reported by Reuter et al. (1996). Propolis also from natural alternative products such as garlic significantly reduced plasma triglyceride concentrations in broilers (Tekeli et al., 2008).In conclusion, using garlic in broiler chicks feed resulted in a significant positive effect on broiler chicks’ growth performance and carcass yield.
The optimum inclusion rate of garlic for growth performance and carcass yield was found to be 0.3%. Further studies in the area of the effects of garlic powder inclusion on immune response are recommended.