The use of antibiotic based growth promoters is presently facing serious problem and has raised global concern as some reports revealed their ill effects among which are development of microbial resistance to the products and their potential harmful effects on human health (Rahmatnejad et al., 2009). Moreover, antibiotics lead to drug resistance in bacteria and drug residues in meat (Issa and Omer, 2012). These shortcomings lead to the search for alternative substances that eliminate these threats. Garlic has several beneficial effects on humans and animals having antimicrobial, antioxidant, anticancer, immunomodulatory, hypoglycemic, anti-inflammatory as well as antihypertensive properties (Reuter e al., 1996 and Sivam, 2001). These functions are mainly attributed to the bioactive components present in garlic (Amagese et al., 2001), which is a sulpher containing organic compound known as diallyl polysulphide which possesses antimicrobial activity (Tsao and Yin, 2001) that could be responsible for the growth promoting effects of garlic. Recently, various probiotic in powder form are available in the markets which are commercially used in broiler chicken as growth promoter. Further, to enhance the activity of these probiotics, prebiotics are essential. These prebiotics are found naturally in a variety of food. The most common prebiotics are inulins and fructooligosaccharides (FOS) (Messina, 1995). The insulin is found in significant quantities in several vegetables, especially garlic. The insulin content of local variety of garlic of Assam was estimated and it was found that it contained about 13% on dry weight basis. Considering the above facts in view the present study was undertaken to determine the effect of garlic as prebiotic on the production performance of broiler chicken fed at different levels with feeds.
Materials and Methods
The biological trail was conducted in the Experimental Poultry shed of Department of Poultry Science, C.V. Sc., Khanapara, Guwahati with 144 numbers of day-old broiler chicks having uniform body weight from a single hatch.
Table 1: Ingredients and nutrient composition of broiler starter and broiler finisher.
The chicks were randomly divided into four groups viz, T0, T1, T2 and T3 comprising 36 chicks in each group. Each group was further subdivided into 3 replicates of 12 chicks in each. The chicks were wing banded and reared under deep litter system of management. The control group (T0) was fed with basal diet without any supplementation and the treatment group T1, T2 and T3 were supplemented with garlic powder at the rate of 0.5, 1.0 and 1.5 percent respectively. All the experimental birds were also provided with probiotic powder (Probios) at the recommended dose of 1g/litre of drinking water. The birds were fed as per recommendation of BIS (1992) feeding standards to meet the energy and protein requirements during starter phase (0- 28 days) and finisher phase (29-42 days). The ingredient and nutrient composition of mash feed for starter and finisher basal diet is presented in Table 1. All the birds were offered ad libitum drinking water and feed throughout the experimental period of six weeks under uniform managemental condition. The birds were vaccinated against Newcastle disease at the age of 7 days with Lasota strain, and infectious Bursal disease at 14 days of age using IBD ‘MB’ intermediate strain. The performance of broiler in respect of weekly feed intake, weekly body weight and body weight gain, feed conversion ratio (FCR) and broiler performance efficiency index (BPEI) were calculated as per standard methods. One Way Analysis of Variance was performed by the software SAS Enterprise Guide 4.2.
Results and Discussion
Weekly Feed Intake and Total Feed Consumption
On perusal of the mean weekly feed intake of the present study (Table 2) it could be seen that during the first and second weeks of age, the feed intake was lowest in T0 group whereas highest in T1 group. During the sixth week of age, highest feed intake was found in T2 group (1032.72g) and lowest in T1 group (988.06g). Thus, it was found from all the weeks that supplementation of garlic powder at 0.5, 1.0 or 1.5 per cent level improved feed intake as compared to control group. Similar findings with respect to improvement in feed intake were observed by several workers (Eltazi et al., 2014 and Karangiya et al., 2016). In contrary to the present observation, Issa and Omer (2012) noted no significant differences in feed intake between the control and treated groups of broiler chicken.
Table 2: Mean weekly feed intake (g/bird) and total feed consumption (g/bird)
The total feed consumption per broiler for different experimental groups was highest in T2 group (3633.23g) and lowest in T0 group (3390.96g). This observation corroborated well with the findings of Ramiah et al. (2014) and Brzoska et al. (2015). The increased feed intake in garlic fed groups might be due to the synergistic effect of the combination of probiotic and garlic powder.
Weekly Body Weight and Body Weight Gain
The mean (± SE) weekly body weight (Table 3) of different experimental groups did not differ significantly during the first and second week of age. On third week, body weight differed significantly (P<0.05) among the different experimental groups. The T2 group achieved significantly (P<0.05) higher body weight (681.67 g) as compared to control group (634.17 g). During the fourth, fifth and sixth week of age, the body weight of broiler chicken differed significantly (P<0.01) among the different groups. The T2 group gained significantly (P<0.05) highest body weight as compared to control group during the fourth, fifth and sixth week respectively. Similar observations were made by Lukanov et al. (2015) and Brzoska et al. (2015), who reported that supplementation of garlic powder, improved the final body weight of broiler chicken. Contrary to the present observation, Fadlalla et al. (2010) and Issa and Omer (2012) reported that body weight was not affected by the supplementation of garlic powder in broiler chicken.
Table 3: Mean (± se) weekly body weight (g/bird) of broilers under different treatments.
The mean (± SE) weekly body weight gain (Table 4) of different experimental groups did not differ significantly in the first and second week of age. Similar observations were recorded by few workers (Jakubcova et al., 2014) who reported that body weight gain of broiler chicken was not affected by the supplementation of garlic powder in feed.
On third, fourth, fifth and sixth week, the mean (± SE) weekly body weight gain differed significantly (P<0.01) among the different treatment groups. In third, fourth and sixth week of age, the T2 group achieved significantly (P<0.05) higher body weight gain as compared to control group. The improvement in body weight and body weight gain of the broiler birds using garlic in their rations may probably be due to the fact that allicin (an antibiotic substance found in garlic), inhibits growth of intestinal bacteria such as Staphylococcus aureus and Escherichia coli and inhibit aflatoxins producing fungi (Meraj, 1998). This study clarified that the birds fed rations supplemented with garlic utilized their feed more efficiently than those ration without addition of garlic. These findings were in agreement with several workers (Karangiya et al., 2016).
Table 4: Mean (± SE) weekly body weight gain (g/bird) of broilers under different treatment groups.
Feed Conversion Ratio
Among the experimental groups, the mean weekly feed conversion ratio (Table 5) of T0 group was best during the first (1.99) and second (1.37) week of age. On the third week, T2 and T3 group (1.39 and 1.39) showed better FCR as compared to T0 (1.46) and T1group (1.49).
Table 5: Mean weekly feed conversion ratio of broilers under different treatment groups.
In fourth week, T1 and T2 group (1.86 and 1.86) showed best FCR and T3 group (1.96) showed poorest value. In fifth week, T3 group (1.71) showed better FCR and T1 group (1.88) indicated poor value. In sixth week, T2 group (1.76) showed best FCR and T0 group (2.26) indicated poorest value. The overall FCR of the entire period of experiment was best in T2 (1.67) followed by T3 (1.74), T0 (1.78) and T1 (1.80) group. The feed conversion ratio was affected significantly (P<0.05) by the experimental diets. There was a significant (P<0.05) improvement in the feed conversion ratio of the birds fed on diets supplemented with garlic powder compared to the control diet. The best feed conversion ratio was significantly (P<0.05) obtained by the diet with 1.0% level of garlic powder. The better feed conversion ratio can be attributed to the anti-bacterial properties of the garlic powder which resulted in better absorption of the nutrients in the gut and finally leading to improvement in feed conversion ratio. Similar observations were reported in broiler chicken by several workers (Lukanov et al., 2015 and Karangiya et al., 2016) who found significantly (P<0.05) improved FCR due to supplementation of garlic powder at various levels. Contrary to the present findings, Issa and Omer, (2012) and Amouzmehr et al. (2013) found no significant differences in FCR due to supplementation of garlic powder in feed of broiler chickens. The improved performance traits in respect of feed consumption, body weight and FCR in garlic treated groups might be due to the fact that garlic contained high levels of allicin, diallyl disulfide and S-methylcysteine sulfoxide (Chi et al., 1982 and Lee et al., 2000).
Broiler Performance Efficiency Index and Livability
Among the different experimental groups, T2 showed the highest BPEI (130.24) followed by T3 (115.45), T1 (110.28) and T0 (106.96) group (Table 6).
Table 6: Broiler performance efficiency index (BPEI) and per cent livability of broilers under different treatment groups.
Similar findings with respect to improvement in performance index and efficiency factor were observed by earlier researchers (Brzoska et al., 2015) in broiler chicken. However, Horton et al. (1991) and Milosevic et al. (2013) did not find any significant differences in performance index among control and garlic fed experimental groups. The higher EPEI value corresponds to higher average body weight; superior livability and higher feed conversion ratio in a stipulated period of experimental trial and thus indicates overall economics feeding in birds (Saiyed et al., 2015). Hence, on the basis of BPEI, it can be stated that supplementation of garlic in the diet of birds was found to be more economical than other groups.
The per cent livability of all the experimental groups was cent per cent (100). Similar observations were reported by Tazi et al. (2012) in broiler chicken fed with diet supplemented with garlic essential oil as natural growth promoter. It might be due to the insulin fermentation in the colon by beneficial bacteria which has been associated with enhancing the gastrointestinal system and immunity system. In addition, it has been shown that it increases the absorption of calcium and magnesium. Contrary to the present observation, several workers (Eltazi et al., 2014 and Puvaca et al., 2014) found variable mortality rates in broiler chicken fed control and garlic treated diets.
Economics of Production
The cost of production per broiler including the additional cost of garlic powder (Table 7) was found to be (Rs.) 144.70, 157.59, 166.31 and 167.87 for T0, T1, T2 and T3 groups respectively (Table 7). The cost of production of per broiler in T3, T2 and T1 was numerically higher by about (Rs.) 23.17, 21.61 and 12.89 as compared to T0 group. However, gross profit per broiler was found to be highest in T2 group (Rs. 51.19) followed by T0 (Rs. 45.73), T1 (Rs. 41.01) and T3 (Rs. 32.93) group. Thus, among the four groups, the T2 group was best in respect of higher gross profit per broiler. The gross profit per broiler was higher by Rs. 5.46 in T2 as compared to T0. The higher gross profit per broiler in T2 was due to increased body weight and improved FCR as compared to other groups. These findings were in agreement with the reports of earlier workers (Eltazi et al., 2014) who found highest revenue and higher profitability ratio with garlic powder fed groups at certain levels.
Table 7: Cost of production and gross profit (Rs.) per broiler under different treatment groups.
A study trial was conducted to investigate the effect of feeding garlic (Allium sativum) powder as prebiotic on the performance of broiler chicken. A total of 144 numbers of day old broiler chicks with uniform body weight were randomly divided into four groups viz. T0 (Standard basal diet as control), T1 (basal diet + 0.5 percent garlic powder), T2 (basal diet + 1.0 percent garlic powder) and T3 (basal diet + 1.5 percent garlic powder) comprising 36 chicks in each group. The final body weight was significantly (P≤0.05) higher in T2 group (2175.00g) followed by T3 (2008.3g), T1 (1986.11g) and T0 (1904.86g). In respect of overall FCR, the T2 group showed the best FCR value of 1.67 followed by T3 (1.74), T0 (1.78) and T1 (1.80). The study revealed that there was increased body weight, improved FCR, highest BPEI and cent per cent livability and higher gross profit per bird offered with 1.0 percent garlic powder in feed. Thus, it can be recommended that in presence of probiotic, garlic can be used as natural prebiotic in feed at the level of 1.0% to improve the overall performance of broiler chicken. The effective level of incorporation of garlic powder at 1.0% might be due to the hormesis effect.
The authors express thankfulness to the Dean, Faculty of Veterinary Science, AAU, Khanapara for providing necessary facilities to carry out the experiment.
This article was originally published in International Journal of Livestock Research, 7(7), 225-233. http://dx.doi.org/10.5455/ijlr.20170520043023. This is an Open Access article distributed under a Creative Commons Attribution License.