One hundred and fifty, day old Japanese quail chicks obtained from a local hatchery were utilized in the experiment. Quail chicks were wing banded and weighed individually. All chicks were divided into five treatments. Each treatment contained three replicates with ten chicks per replicate allotted at random. The experiment was conducted for 5 weeks duration.

Broiler quail starter and finisher diets (Table 1) were prepared to meet the nutrient requirements (ICAR, 2013). During different phases of the trial, experimental diets were prepared by including dried garlic powder (GP) at 0% (T₁; Control), 0.5% (T₂), 1.0% (T₃), 1.5% (T₄) and 2.0% (T₅) levels. All the diets were made iso-caloric and iso-nitrogenous.

All the chicks were housed in battery brooders throughout the experiment. All the cages were provided with uniform brooding facilities, feeders and waterers. Irrespective of the treatments, all the chicks were fed ad-libitum 2 times a day with respective broiler quail starter diet from 0-3 weeks and finisher diet from 4-5 weeks of age. Fresh and clean drinking water was made available at all the time.

At the end of study period (5^th week), two birds per replicate and thus a total 6 birds per treatment were randomly selected, weighed and slaughtered. At the time of slaughter, blood samples were collected from each bird to determine serum biochemical parameters using diagnostic kits (M/s. Span Diagnostics Private Limited).

All the data were analyzed statistically (SPSS, 17^th Version) as per Snedecor and Cochran (1994) and comparison of means was done using Duncan’s multiple range tests (Duncan, 1955).

The serum total protein content (mg/dl) of quails increased significantly (P<0.05) with increased levels of dried garlic powder from 0 to 2.0% in the diet (Table 2). It is reported that dried garlic powder has anti-microbial, anti-fungal effects and contain anti-oxidants that decrease lipid oxidation (Canogullari et al., 2010) which might have enhanced the immune system resulting in increased serum total protein concentration in quails. These results corroborated with the findings of Shamsa et al. (2013) who reported increased (P<0.05) serum total protein concentration in broilers upon feeding diets containing 4% garlic. Similarly, Brzoska et al. (2015) also reported significantly (P<0.01) higher serum total protein upon adding liquid garlic extract at 2.25 ml / kg in broiler diet. However, many researchers reported that feeding of garlic in the diet had no effect (P>0.05) on serum total protein in broilers (Yalcin et al., 2006; Ao et al., 2010; Fadlalla et al., 2010) and laying hens (Motamedi and Taklimi, 2014).

Inclusion of dried garlic powder up to 2% in the diet had no effect (P>0.05) on serum albumin content (mg/dl) of quails (Table 2). Corroborating the results of the present study, Fadlalla et al. (2010) reported that feeding graded levels of garlic up to 0.6% level in the diet of broilers had no effect (P>0.05) on serum albumin content. Ao et al. (2010) in laying hens and Onu (2010) in broiler chicken also reported similar findings. In contrast to these findings, Shamsa et al. (2013) reported increased (P<0.05) serum albumin content in broiler chicken fed diets containing 4% garlic powder as compared to the control.

Increased levels of inclusion of dried garlic powder from 0 to 2% in the diet had no effect (P>0.05) on serum globulin content (mg/dl) of quails (Table 2). In line with the present findings, Fadlalla et al. (2010) reported that feeding graded levels of garlic up to 0.6% level in the diet of broilers had no effect (P>0.05) on serum globulin content while Onu (2010) reported that feeding garlic at 0.25% level in the diet of finisher broilers had no effect (P>0.05) on serum globulin content. Similar findings were reported by Motamedi and Taklimi (2014) in laying hens.

The serum glucose content (mg/dl) decreased significantly (P<0.01) with increased levels of dried garlic powder from 0 to 2.0% in the diet of quails (Table 3). These results agree with the findings of Shamsa et al. (2013) who reported a significant decrease (P<0.05) in serum glucose concentration in broilers when fed 4% garlic in the diet as compared to the control. However, several researchers reported no effect (P>0.05) on serum glucose concentration in broiler chicken (Horton et al., 1991; Canogullari et al., 2010; Kim, 2010) and turkey hens (Krauze et al., 2012) upon feeding dried garlic powder in the diet.

The serum triglyceride content (mg/dl) of quails decreased significantly (P<0.01) with inclusion of dried garlic powder up to 2.0% in the diet (Table 3). These results agree with the findings of Ademola et al. (2009) who reported that supplementation of dried garlic powder at 1.0, 1.5 and 2.0 % in the diet had resulted in significant decrease (P<0.01) in serum triglyceride content of broilers. The decreased serum triglyceride content observed in quails upon feeding dried garlic powder in the diet might probably be due to the possible mechanism of allicin, the organosulfur component of garlic, combining with the –SH group (Cavallito et al., 1944), the functional part of CoA, which is necessary for the biosynthesis of triglycerides. Binding of allicin to the enzyme is non-covalent and reversible in nature. Inhibition of fatty acid and lipid formation by allicin may be a basis for hypo-cholesterolaemic and hypolipidemic action of garlic (Focke et al., 1990).

Similarly, Yalcin et al. (2006), Dehkordi et al. (2009), Prasad et al. (2009), and Issa and Omar (2012) reported significantly decreased serum triglyceride content in broiler chicken upon feeding dried garlic powder in the diet. However, some researchers (Canogullari et al., 2010; Kim, 2010; Amouzmehr et al., 2012; Puvaca et al., 2014; Brzoska et al., 2015) reported that feeding dried garlic powder in the diet had no effect (P>0.05) on serum triglyceride content in broiler chicken.

Effect on serum total cholesterol

The serum total cholesterol content (mg/dl) decreased significantly (P<0.01) with increased level of incorporation of dried garlic powder from 0 to 2.0% in the diet of quails (Table 3). Similarly, Ademola et al. (2009) reported that supplementation of dried garlic powder up to 2.0 % in the diet resulted in decreased (P<0.01) serum total cholesterol content in broilers. The decrease in the serum cholesterol levels observed could be attributed to the hypo-cholesterolaemic and hypolipidemic action of garlic products which depresses the hepatic activities of lipogenic and cholesterogenic enzymes such as malic enzyme, fatty acid synthase, glucose-6-phosphatase dehydrogenase (Qureshi et al.,1983a) and 3-hydroxy-3-methyl-glutarylCoA (HMG-CoA) reductase (Qureshi et al.,1983b). In corroboration, several researchers reported that inclusion of dried garlic powder resulted in significantly decreased serum total cholesterol content in broiler chicken (Yalcin et al., 2006; Safaa, 2007; Khan et al., 2007; Dehkordi et al., 2009; Prasad et al., 2009; Kim, 2010; Ao et al., 2010; Issa and Omar, 2012) and laying quails (Canogullari et al., 2010).

The serum HDL cholesterol content (mg/dl) of quails increased significantly (P<0.01) with increased level of dried garlic powder from 0 to 2.0% in the diet (Table 3). In line with the present findings, Ademola et al. (2009) reported that feeding garlic at 1.0, 1.5 and 2.0% level in the diet resulted in increased (P<0.01) serum HDL cholesterol concentration in broiler chicks. The increased serum HDL content observed in quails upon feeding dried garlic powder in the diet might be attributed to the significant hypo-lipidemic effect resulting in lowering the total cholesterol levels and triglycerides and thus increasing the levels of high-density lipoprotein. Similarly, increased serum HDL cholesterol levels upon feeding garlic in the diet were also reported earlier (Safaa, 2007; Prasad et al., 2009; Kim, 2010; Canogullari et al., 2010; Issa and Omar, 2012; Puvaca et al., 2014).

Serum LDL cholesterol content (mg/dl) decreased significantly (P<0.01) with increased level of dried garlic powder from 0 to 2.0% in the diet of quails (Table 3). The decreased serum LDL content observed in quails upon feeding dried garlic powder in the diet may probably be due to the possible mechanism of antioxidant and antiperoxide lowering action of garlic products i.e. S-allyl Cysteine Sulfoxide (SAC) on LDL-C or decrease in hepatic production of VLDL-C which serves as the precursor of LDL-C in the blood circulation (Grundy, 1986). In line with these findings, several researchers reported that inclusion of dried garlic powder resulted in significantly decreased serum LDL cholesterol (Safaa, 2007; Khan et al., 2007; Ademola et al., 2009; Prasad et al., 2009; Kim, 2010; Issa and Omar, 2012; Puvaca et al., 2014) in broiler chicken and Canogullari et al., 2009; and Motamedi and Taklimi (2014) in laying hens. In contradiction, Canogullari et al. (2010) reported significantly increased serum LDL cholesterol in laying quails fed garlic powder in the diets.

The serum VLDL cholesterol content (mg/dl) of quails decreased significantly (P<0.01) with increased level of dried garlic powder up to 2.0% in the diet (Table 3). Prasad et al. (2009) reported that supplementation of dried garlic powder at 0, 1.5 and 3.0 % in the diet had resulted in significant decrease (P<0.01) in serum VLDL cholesterol content of broilers. The possible mechanism of lowering VLDL cholesterol by garlic products is unclear. However, it may probably be attributed to the increase in the esterified cholesterol by garlic supplementation which may be a result of decreased production or increased excretion of esterified cholesterol through bile (Girish Kumar et al., 1998). This might have resulted in significant decrease (P<0.01) in VLDL cholesterol concentration in quails.

The serum creatinine content decreased (P<0.01) with increased level of dried garlic powder from 0 to 2.0% in the diet of quails (Table 3). Reddy et al. (2018) reported that feeding coriander as natural feed additives in the diet of quails resulted in decreased serum creatinine content in Japanese quails. Significant increase in serum uric acid and creatinine levels are indicative of nephrotoxicity in broiler chickens (Huff et al., 1988). Thus, the decreased (P<0.01) serum creatinine content observed indicate improved kidney health in terms of filtration rate which may be attributed to the incorporation of dried garlic powder in the diet. In contradiction, Krauze et al. (2012) reported that creatinine levels showed a significant (P<0.01) increase in turkey chicken fed garlic powder in the diet while several authors (Onu, 2010; Onyimonyi et al., 2012; Gerzilov et al., 2015) reported no effect (P>0.05) on serum creatinine content in broiler chicken.