Use of the antibiotics in feed has shown several side effects like resistance towards the drug, residue in the meat and thereby the user getting resistance to the drug etc. hence several countries have banned the use of antibiotic based growth promoters in the feed animal sector and appearance of resistant strains in human beings. Alternative plant extracts and essential oils have been known to be used for many kinds of diseases by Egyptians, Chinese, Indians and Greeks. Garlic is known to contain an array of substances with beneficial health-related biological properties (Agarwal, 1996). Class of sulfur containing organic compounds, which are commonly known as organo sulfur compounds are known to have several medicinal properties. Compounds like dialkyl polysulfides are known to be having antimicrobial activity (Shyh-Ming and Mei-Chin, 2001). El-Husseiny et al. (2002) revealed that chicks fed hot pepper diet had significantly higher body weight gain and digestion coefficients of nutrients than the control. Abdo et al. (2003) reported that adding hot pepper at 1.5 % resulted in reducing the counts of harmful microorganisms such as molds, salmonella and E. coli of the gastrointestinal tract when compared to the control. The present experiment was designed to study the possibility of using dried garlic or hot pepper as supplements to laying Japanese quail diets to evaluate its effect on productive performance, egg quality, blood constituents, digestibility and also its effect on harmful bacteria.
Material and Methods
A total of 160 laying Japanese quail hens which had been in production for 12 weeks were randomly allocated in a completely randomized design considering five groups with four replicates and 8 laying hens each. The birds were selected on the basis of more than 70 % egg production rate after a two-week pre-treatment period in open house system. The experimental treatments were: The first group received the basal diet with no supplements (control). The second and third groups were fed the basal diet supplemented with 0.75 or 1.5% of dried garlic, respectively. The fourth and fifth groups were fed the same basal diet with supplementation of 0.75 or 1.5 % of hot pepper, respectively. The basal diet was formulated according to NRC (1994). It contained 20 % crude protein and 2700 Kcal / Kg metabolizable energy. Fresh feed was mixed weekly and not stored for more than one week. The hens were reared in wire batteries under similar environmental conditions. All birds had full access to feed and water. The photoperiod was 16 hours of light per day throughout the experimental period, which lasted for 12 weeks. Records were kept for egg production, feed consumption, egg weight, average body weight change and mortality. Measurements of egg quality were taken on average of 21 eggs from each treatment and were performed through two consecutive days per month. At the last week of the experiment, 12 eggs were collected from each treatment-group and divided into 4 replicates of 3 eggs each. Yolks and albumins of the 3 eggs from each replicate were separated and their chemical composition was determined according to the methods of A. O. A. C. (1990). Yolk cholesterol was extracted by the method of Folch et al. (1956) as modified by Washburn and Nix (1974) from three eggs of each replicate. Blood samples from the brachial vein of 3 hens in each treatment were drawn and plasma were obtained by centrifugation of blood at 3500 r.p.m. for 15 min. and kept at – 18º C until analyzed. Plasma total protein, albumin, total lipids and cholesterol were calorimetrically determined using commercial kits (from Biomerieux, Poains, France). The digestibility coefficients of nutrients of the experimental diets were determined using six adult male birds for each treatment. Faecal nitrogen was determined following the procedure outlined by Jakobsen et al. (1960). Pathogenic bacteria were counted and defined as the procedure of A. O. A. C. (1990). Computerizes one-way analysis of variance, and Duncan’s multiple range test procedures using (SAS software, 1996) were run to comparison of treatment groups.
Results and discussion
Body weight change of birds was not significantly affected by different treatments. The results showed that the supplementation of 0.75 % dried garlic resulted in significant (p ≤ 0.01) improvements in egg production by the value of 6.8 %, egg weight (p ≤ 0.01) by 6.5 %, eggs mass/hen/day (p ≤ 0.01) by 13.7 %, and feed conversion ratio (p ≤ 0.01) by 13.0%, respectively, as compared to control hens (Table1). It is of interest to note that egg weight did not decline by the increase of egg production in 0.75 % dried garlic fed hens during the experimental period. The results of (Mei Ling and Margaret, 1980; Winterhoff and Egen, 1991 and Elnagar et al., 2005) reported that garlic increased the levels of serum T3, T4 and insulin hormones, these hormones are responsible for increasing the metabolic rate in the body, which may be due to egg production and egg weight improvement. Khalil et al.(2007) showed that feed conversion ratio was significantly better in growing Japanese quail birds fed 1.6 % dried garlic than the control group. Also, Elnagar et al. (2005) found better feed conversion ratio by given tablets containing alliin in Pekin ducklings. Addition of 1.5 % hot pepper in the diet resulted in a significant (p ≤ 0.01) improvement in egg weight by 3.7 % and feed conversion ratio by 7.9 %. A slight numerical improvement was observed in egg production by 3.3 % and egg mass by 7.2 % as compared to the control hens. The addition of dried garlic and hot pepper did not demonstrate any significantly effect on feed consumption. It is of interest to note that egg weight did not decline by the increase of egg production in dried garlic-fed hens during the experimental period. There was no mortality in the groups given the experimental diets during the experimental period.
Table 1. Performance of laying Japanese quail hens fed on experimental basal diets supplemented with dried garlic or hot pepper
Results in Table 2 showed that egg specific gravity; shell weight, relative shell weight, and shell thickness were significantly (P ≤0.05) improved due to adding 0.75 % dried garlic and 1.5 % hot pepper in the diet as compared to the control laying hens. The improvement in egg specific gravity might be associated with increasing of shell thickness and shell weight. Hence, it was anticipated that the level of mineral deposition in egg shells might increase under supplementation of the diet with 0.75 % dried garlic and 1.5 % hot pepper to give thicker shells than in the control treatment.
Table 2. Egg components, egg quality and chemical composition for the egg yolk for laying Japanese quail hens fed on experimental basal diets supplemented with dried garlic or hot pepper
Also, albumin weight significantly (P ≤0.05) increased due to adding 0.75 % hot pepper in the diet. However, dried garlic had insignificant effect on this trait. Zeweil et al. (2006) reported that Japanese quail laying hens fed on diet supplemented with 1 or 2 g thyme flowers / Kg diet did not affect egg quality trait. Results in Table 2 showed insignificant differences were existed among dietary treatments in the chemical composition of egg, except egg yolk cholesterol which was significantly (p ≤ 0.01) decreased by supplementing the diets with 0.75% dried garlic or 1.5 % hot pepper. These results were in agreement, more or less, with those of Zeweil et al., (2006) who reported that inclusion of 1 or 2 g thyme flowers / Kg diet decreased egg yolk cholesterol of Japanese quail laying hens at 24 weeks of age. Results in Table 3 showed that supplemental dried garlic and hot pepper in Japanese quail diets resulted in significant (P ≤ 0.05) decrease in blood plasma total cholesterol and total lipids. The reduction was more pronounced in the plasma of birds fed dried garlic. Results obtained are in agreement with the previous findings of Mottaghitalab and Taraz (2004) who showed that garlic had a significant effect on lowering the level of plasma total lipids and cholesterol of birds. Also, Tollba et al.(2007) reported that total lipids and cholesterol in the plasma of broilers or laying hens fed diet supplemented with hot pepper were significantly (P ≤ 0.01) lower than those of the control groups. The mechanism of this reduction is due to the garlic content of sulfur compounds that responsible for inhibiting biosynthesis of cholesterol and lipids (Chi et al., 1982). One suggestion is that garlic blocks hydroxymethylgutaryl- CoA (HMG-CoA), which reacts with a reductase to yield mevalonate and is rate-limiting step in cholesterol biosynthesis (Mathews and Van Holde, 1990). The different supplementations had positive effect on plasma globulin level which was increased, however, albumin/ globulin ratio was significantly (p ≤ 0.05) decreased (Table 3).
Table 3. Effect of dried garlic or hot pepper on some blood constituents of Japanese quail hens
The increase in globulin value reflects a good immune status which may attribute to the immune-stimulant effect of these supplementations to the diets. Garlic administration increased the antibody titers to sheep RBCs (El-Habbak et al. 1989). This indicated the positive effect of garlic on blood parameters, which were the reflection of healthy conditions of liver and spleen. Results illustrated in Table 4 showed that adding dried garlic to the diet at 0.75 % caused a pronounced (P ≤0.05) increase in digestibility coefficients of crude protein and nitrogen free extract of mature Japanese quail cocks as compared to the control group. Also supplementation of 1.5 % hot pepper in the diet resulted in a significant (P ≤0.05) improvement in digestibility coefficient of nitrogen free extract. On the other hand, Cross etal. (2011) reported that the digestibility for birds given dietary garlic were similar to thecontrol.
Table 4. Digestibility coefficients of nutrients for mature Japanese quail cocks fed on experimental basal diets supplemented with dried garlic or hot pepper
The positive response in protein digestibility due to supplementing the dried garlic could be explained by regulation the microbial environment of the intestines, decrease digestive disturbances, inhibit pathogenic intestinal microorganisms and improve feed conversion efficiency. A significant (P ≤ 0.05) suppressed was detected in the counts of pathogenic feces bacteria due to supplementing the diets with dried garlic or hot pepper as compared to the control group, where severe decreases in counts of E. coli, Salmonella and Streptococci were detected (Table 5). The greatest reduction in harmful bacteria was observed by addition of 0.75 % dried garlic or 1.5 % hot pepper. The faeces microbial counts may explain some of the present results. E. coli, Salmonella and Streptococci are known to be harmful especially when their numbers increase, North (1981). Abdo et al. (2003) and Tollba et al. (2007) found that red pepper reduced the counts of harmful microorganisms such as molds, Salmonella and E. coli and increased the sensitivity of microbial. Kumar et al. (2010) showed that the positive effects of supplemental garlic active growth promoter (G-PRO) could be attributed to its antimicrobial and simulative effects on intestinal digestibility. It could be concluded that the supplementations of dried garlic (0.75 %) or hot pepper (1.5 %) to laying hen diets positively affected performance parameters significantly (p<0.05) and showed also that the supplements were able to reduce the salmonella, E. coli and Streptococci counts in the intestine when compared to the control.
Table 5. Counts of feces pathogenic bacteria (x 106 CFU/g fluid) of Japanese quail laying hens fed on experimental basal diets supplemented with dried garlic or hot pepper
This article was originally published in EggMeat Symposia 2011.