A biological trial was conducted to assess the effect of sodium butyrate on serum biochemistry and meat quality parameters in broiler chicken. The trial consisted of 6 experimental diets. The diets were control group fed diet without antibiotic (AB), group fed diet with AB (Oxytetracycline – 50 ppm), groups fed diet with two levels of coated sodium butyrate (CSB) (0.09 % and 0.18 %) and uncoated sodium butyrate (UCSB) (0.03 % and 0.06 %) without AB. The serum protein fractions, parameters of kidney and liver function tests, HI titre against Newcastle Disease and serum antioxidants were not influenced by the inclusion of AB, CSB or UCSB. CSB at both levels of incorporation was found to lower the total (P<0.01) and LDL cholesterol (P<0.05) when compared to the control diet without AB while, the reduction was significant only at higher level of CSB when compared to group fed diet with AB. UCSB did not influence the cholesterol levels. Supplementation of CSB, UCSB or AB did not alter serum mineral levels, except sodium which was increased (P<0.05) in group fed CSB at 0.18 %. The sensory evaluation and quality parameters of meat were not influenced by treatment groups. The overall acceptability of meat of birds fed both levels of UCSB was poorer than other treatment groups. It can be concluded that supplementation of sodium butyrate did not greatly alter the serum biochemical parameters and meat quality except the reduction of serum total and LDL cholesterol due to coated sodium butyrate.
In modern commercial broiler production, birds are exposed to physiological stress, which results in greater susceptibility to illness, infection and mortality. Antibiotic usage in the aid of overcoming these losses has possible lead to the emergence and dissemination of multiple antibiotic resistant pathogens and reduction in response to human and animal infections. The ban of antibiotic growth promoters in many countries increases the interest to find an alternative to suppress microbial load. Alternate microbial load suppressing agents like probiotics, prebiotics or organic acids have being included to replace antibiotics. Of which, prebiotics are costlier affecting economics in poultry production, while probiotics have different degrees of survivability in feed and in the gut environment.
Organic acids could be the best possible choice for securing the supply of safe food. In poultry production, organic acids have not gained as much attention as in swine production (Langhout, 2000). The dissociation of the organic acid in gut is pH dependant. Generally, short chain fatty acids are preferred acidifiers, among which, butyric acid (BA) is considered as the prime enterocyte energy source, necessary for development of Gut Associated Lymphoid Tissue (GALT) (Friedman and Bar-Shira, 2005) and has the highest bactericidal efficacy against the acid-intolerant species such as Escherichia coli and Salmonella sp. (Kwan and Ricke, 2005). BA has a pKa (4.81) that dissociates in crop. Hence, encapsulation of BA or salt form of BA is done for which allows more BA to reach the distal sections of gastrointestinal tract than monoglyceride of BA (Mallo et al., 2012). The present study was undertaken to evaluate the response of sodium butyrate in coated and uncoated forms both at two different levels as a substitute for antibiotic (oxytetracycline).
Materials and Methods
The experimental broiler pre-starter, starter and finisher diets were formulated by supplementation of coated SB at 0.09 and 0.18 % levels and uncoated SB at levels 0.03 and 0.06 % instead of antibiotic (Oxytetracycline). The antibiotic studied was 10 % oxytetracycline @ 0.05% of feed. The SB used was laboratory grade chemical with 98 % purity and the coated SB; vegetable fatty acid encapsulated containing 30 % SB. The nutrient requirements of formulated diets were as specified by the breeder. The experimental groups were control group (T1) diet without antibiotic (AB), (T2) diet with AB (Oxytetracycline – 50 ppm), (T3, T4) diet with two levels of coated sodium butyrate (CSB) (0.09 % and 0.18 %) and (T5, T6) uncoated sodium butyrate (UCSB) (0.03 % and 0.06 %) without antibiotic (AB). The pre-starter, starter and finisher diets were fed to birds from 1 to 8, 9 to 28 and 29 to 42 days of age respectively. Each group had 12 replicates, each containing six chicks with a total of 432 birds. The birds were housed in deep litter pens and reared under uniform standard managemental practices. At the end of 42 days of age, nine birds per treatment were starved for 12 hours and slaughtered. From all the slaughtered birds, blood was collected and serum separated. The serum samples were analyzed for protein fractions, lipid profile, minerals (calcium, phosphorus), and liver and kidney function tests using the biochemical kits from M/s. Span Diagnostics Ltd., Sachin, India. Serum LDL-cholesterol was calculated by Friedewald equation (Friedewald et al., 1972). The serum sodium and potassium levels were determined using flame photometer as per AOAC (2012).Serum level of superoxide dismutase was measured by the method of Marklund and Marklund (1974). Serum malonaldehyde (MDA) was measured according to Salih et al. (1987), Catalase activity by Claiborne (1985) and Ascorbic acid by Kway (1978) methods and the antibody titre in the serum by Haemagglutination Inhibition test (OIE, 2008).
Breast muscle samples were used to study the meat quality. The fresh breast muscle (5g) collected immediately after slaughter was minced and taken in a beaker containing 45 ml of double glass distilled water (pH – 6.7). The pH of meat was estimated using Oaklon multiparameter PCSTM35 tester and the water holding capacity by filter paper press method (Grau and Hamm, 1957). Accurately weighed (300 mg) of muscle was kept in-between a folded Whatman filter paper. The folded filter paper with meat was then kept in-between two glass slides. The muscle tissue was subjected to a downward force by placing a 100g weight on the top of the upper glass slide for 3 minutes. The areas of the two resultant wet impressions were expressed in square centimeter. The tenderness of meat sample was estimated by shear force value. The measurement of shear force value was carried out using a Warner – Bartzler meat shear (G.R. Electric Manufacturing Company, Manhattan, U.S.A.,) and cooking loss by Pearson and Dutson (1994).
Fresh coded breast muscle sample was pressure cooked using domestic pressure cooker until the internal temperature of the breast muscle was sufficient to cook the meat. The cooked samples were cut into 1 cm slices and the samples were served to a panel of members (6 numbers) selected for sensory evaluation and evaluated with a score card of eight hedonic points (Appendix A) to assess the colour, appearance, flavor, texture, juiciness, tenderness and overall acceptability of the meat. The data collected on various parameters were subjected to analysis of variance test and the means of different experimental groups were compared by Duncan’s multiple range test using SPSS software (version 20.0).
Results and Discussion
Serum Protein and Lipid Profile
The results of serum protein and lipid profile due to supplementation of sodium butyrate are presented in Table 1. The total protein, albumin, globulin (g/dl) and A/G ratio were not influenced by the inclusion of AB, CSB or UCSB. The levels of protein fractions were in normal range suggesting good nutritional status of the birds with no pathological liver lesions in all the treatment groups (Abdl-Rahman et al., 2010).
Table 1: Effect of sodium butyrate supplementation at different levels and forms on serum protein and lipid profile in broilers
|Treatment groups||Total protein (g/dl)||Albumin (g/dl)||Globulin (g/dl)||Albumin: Globulin ratio||Total cholesterol**(mg/dl)||HDL (mg/dl)||LDL* (mg/dl)||Cholesterol: HDL Ratio||HDL: LDL Ratio||Triglycerides (mg/dl)|
|Control diet without AB (C)||5.51± 0.29||2.78± 0.36||2.73± 0.36||0.94± 0.15||190.1c ± 2.2||76.2± 8.9||84.2c ± 11.3||2.85± 0.62||1.01 ± 0.16||138.4± 7.2|
|C + AB (50 ppm)||5.71± 0.37||2.61± 0.31||3.09± 0.44||0.85± 0.19||184.8bc ± 4.4||77.6± 4.4||77.7bc± 8.1||2.41± 0.14||1.09 ± 0.19||137.3 ± 9.8|
|C + 0.09 % CSB||5.95± 0.39||2.28± 0.20||3.67± 0.53||0.65± 0.08||177.8ab± 4.1||91.1± 9.2||58.5ab± 8.9||2.04± 0.19||2.02 ± 0.62||130.8± 4.1|
|C + 0.18% CSB||6.04± 0.18||2.17± 0.15||3.86± 0.25||0.61± 0.06||169.3a ± 3.1||92.5± 2.4||49.5a ± 2.7||1.83± 0.04||1.90 ± 0.13||126.6 ± 2.1|
|C + 0.03 % UCSB||5.86± 1.0||2.36± 0.27||3.49± 0.24||0.79± 0.07||183.4bc ± 3.6||82± 3.4||72.9bc± 5.3||2.25± 0.10||1.17 ± 0.14||132.3 ± 3.9|
|C + 0.06 % UCSB||5.9± 0.49||2.38± 0.23||3.54± 0.38||0.8± 0.14||185.1bc ± 3.8||90.8± 3.2||66.0abc± 3.5||2.04± 0.05||1.40 ± 0.11||131.2 ± 4.2|
Each value is a mean of six observations; Means with at least one common superscript in a column do not differ significantly at * P>0.05, ** P>0.01; AB= Antibiotic (Antibiotic used was oxytetracycline), CSB = Coated Sodium Butyrate, UCSB = Uncoated Sodium Butyrate
On the other hand, there was increased total protein and globulin in group fed CSB at 0.18 % when compared to AB free group. Supplementation of butyric acid glycerides (Mahdavi and Torki, 2009) and butyric acid (Kamal and Ragaa, 2014) have not influenced serum total protein, but in the latter work serum globulin level was significantly (P<0.05) high. Higher (but P>0.05) globulin concentrations and lower (but P>0.05) albumin to globulin ratio signify better disease resistance and immune response (Griminger, 1986) consistent with the enhanced immune response of organic acid supplementation (Abdel-Fattah et al., 2008).
CSB at both levels of incorporation was found to significantly (P<0.01) lower the total cholesterol (169.3 – 177.8 vs. 190.1 mg/dl) and LDL cholesterol (P<0.05) (49.5 – 58.5 vs. 84.2 mg/dl), but the HDL cholesterol was higher (P>0.05) when compared to the control diet without AB. At higher level of CSB, total cholesterol (169.3 vs. 184.8 mg/dl) and LDL (49.5 vs. 77.7 mg/dl) were lower than the control diet with AB. UCSB did not influence the total cholesterol and LDL when compared to control with or without AB and low levels of CSB. The CSB fed birds at both the levels had lower cholesterol to HDL ratio (P>0.05) and higher HDL to LDL ratio (P>0.05). The serum lipid profile of broilers has positive correlation with the muscle lipid profile level (Salma et al., 2007). Hence, the serum lipid profile in this study suggested that the feeding of CSB might help in production of healthy chicken meat. The triglyceride level in different treatment groups was comparable. Similar to the present study, work done by Taherpour et al. (2009), Jang (2011), Mansoub (2011) and Kamal and Ragaa (2014) showed reduced levels of serum total cholesterol and LDL with comparable HDL levels due to addition of various forms of BA. In the same way, Taherpour et al. (2009), Zhang et al. (2011a) and Kamal and Ragaa (2014) found comparable triglyceride level by inclusion of different forms of butyric acid.
Serum Mineral Profile and Kidney and Liver Function Tests
The effect of supplementation of SB on serum mineral profile and kidney and liver function tests are presented in Table 2.
Table 2: Effect of sodium butyrate supplementation at different levels and forms on mineral profile, kidney and liver function tests in broilers
|Treatment groups||Calcium (mg/dl)||Phosphorus (mg/dl)||Sodium*(meq/l)||Potassium (meq/l)||ALT(IU/L)||AST(IU/L)||Uric acid*(mg/dl)||Creatinine (mg/dl)|
|Control diet without AB (C)||10.72 ± 0.09||3.77 ± 0.19||140.56 a± 1.86||4.00 ± 0.26||20.03 ± 0.70||52.74 ± 2.96||6.61b ± 0.23||2.00 ± 0.91|
|C + AB (50 ppm)||10.96 ± 0.38||3.68 ± 0.14||140.03 a± 1.54||3.90 ± 0.23||19.44 ± 1.42||51.27 ± 1.66||6.51 b± 0.20||1.98 ± 0.68|
|C + 0.09 % CSB||11.48 ± 0.52||3.71 ± 0.53||141.81ab± 2.75||4.10 ± 0.14||18.26 ± 0.58||47.73 ± 3.63||4.80 a ± 0.60||2.36 ± 0.40|
|C + 0.18% CSB||12.54 ± 0.66||3.26 ± 0.05||147.36 b± 2.60||4.30 ± 0.22||17.53 ± 1.17||45.96 ± 5.47||5.40 ab± 0.36||2.76 ± 0.28|
|C + 0.03 % UCSB||11.79 ± 0.29||3.48 ± 0.17||137.50 a± 1.62||4.20 ± 0.29||17.53 ± 1.45||49.79 ± 2.17||6.41 b± 0.57||2.99 ± 0.19|
|C + 0.06 % UCSB||11.21 ± 0.73||3.32 ± 0.08||139.90 a± 1.51||3.80 ± 0.17||17.53 ± 0.80||49.04 ± 2.75||4.85 a± 0.76||2.97 ± 0.25|
Each value is a mean of six observations; Means with at least one common superscript in a column do not differ significantly at * P>0.05; AB = Antibiotic (Antibiotic used was oxytetracycline);CSB = Coated Sodium Butyrate;UCSB = Uncoated Sodium Butyrate
Supplementation of CSB, UCSB or AB did not alter serum calcium, phosphorus and potassium levels, except sodium which was significantly increased in group fed CSB at 0.18 % when compared to control without AB. This might be due to the fact that butyrate induces absorption of water and sodium as demonstrated by Kripke et al. (1989) and Friedel and Levine (1992). Though, the value of calcium was within the normal range, an increased (P>0.05) in serum calcium observed in this study suggested that acidification of feed increases calcium absorption in intestine by decreasing the pH of digesta, in turn inhibiting phytic acid from formation of calcium-phytate complex (Boling et al., 2000; Rafacz-Livingston et al., 2005). Contrast to the present study, earlier works showed increased serum calcium (Mahdavi and Torki, 2009; Adil et al., 2010; Kamal and Ragaa, 2014), phosphorus (Adil et al., 2010; Kamal and Ragaa, 2014) and magnesium levels (Kamal and Ragaa, 2014) by addition of different forms of butyric acid. Since the serum potassium level in this study was within normal range, it suggested no shift of this element from intracellular to extracellular space and cellular pathology.
The values of ALT, AST, uric acid and creatinine are in normal range suggesting that SB or AB had not affected the hepatocytes. Moreover, the changes in uric acid can be ignored as butyric acid does not cause toxicity due to its rapid addition of CSB and UCSB up to 0.18 and 0.06 % respectively. Similarly, some studies showed that, supplementation of various forms of butyric acid have not altered ALT and AST levels (Adil et al., 2010; Kamal and Ragaa, 2014) and serum creatinine (Ali et al., 2014; Kamal and Ragaa, 2014).
Serum Antioxidant Properties and Haemagglutination Inhibition Titre
The responses of SB on serum antioxidant properties and Haemagglutination inhibition titre against ND are presented in Table 3.
Table 3: Effect of sodium butyrate supplementation at different levels and forms on serum antioxidant property and Haemagglutination Inhibition titre (log2) against Newcastle disease
|Treatment groups||SOD(U/ml)||Catalase (U/ml)||Ascorbic acid (U/ml)||MDA (nmol/ml)||Haemagglutination inhibition test|
|Control diet without AB (C)||92.18 ± 2.44||2.89 ± 0.27||0.51 ± 0.08||1.90 ± 0.19||4.83 ± 0.16|
|C + AB (50 ppm)||96.09 ± 4.01||3.10 ± 0.30||1.04 ± 0.28||1.60 ± 0.16||5.00 ± 0.25|
|C + 0.09 % CSB||103.12 ± 4.29||2.85 ± 0.19||0.60 ± 0.11||1.70 ± 0.14||4.83 ± 0.16|
|C + 0.18%CSB||99.73 ± 5.10||3.53 ± 0.30||0.90 ± 0.27||1.53 ± 0.12||5.16 ± 0.30|
|C + 0.03 % UCSB||104.03 ± 5.41||3.46 ± 0.24||0.96 ± 0.20||1.75 ± 0.17||5.16 ± 0.16|
|C + 0.06 % UCSB||103.64 ± 7.09||3.36 ± 0.15||0.93 ± 0.28||1.62 ± 0.17||4.83 ± 0.16|
Each value is a mean of six observations; AB = Antibiotic (Antibiotic used was oxytetracycline), CSB = Coated Sodium Butyrate, UCSB = Uncoated Sodium Butyrate
Serum antioxidants such as SOD, catalase, ascorbic acid and MDA were not influenced by supplementation of SB (coated and uncoated) or AB. However, there was an increase in (P>0.05) catalase and SOD and decreased (P>0.05) MDA levels due to the addition of CSB or UCSB, indicating the presence of mild antioxidant properties of SB. But the earlier work of Zhang (2011a) showed, SB significantly increased SOD and catalase and lowered MDA levels. It was observed that CSB, UCSB or AB do not significantly increase the titre level against ND suggesting that they do not alter the immune response. Similarly, El-Deek et al. (2012a and b) also found that supplementation of oxytetracycline did not alter the Haemagglutination inhibition titre against RD.
Sensory Evaluation and Quality Parameters of Meat
The effect of SB on the sensory evaluation of meat and quality parameters such as meat pH, cooking loss, shear force value and water holding capacity are presented in Table 4. All the above physical qualities of the meat were comparable between treatment groups. The present results were in line with the work of Zhang et al. (2011b). On sensory evaluation of meat, all the parameters except juiciness quality of meat were found to be comparable between treatment groups. Juiciness of the meat samples was lowest (5.7) in group fed CSB at 0.09 % and highest (6.9) in group fed CSB at 0.18 %. The overall acceptability of meat of birds fed both levels of UCSB was poorer (P>0.05) than birds fed diet with CSB or control with or without AB.
Table 4: Effect of sodium butyrate supplementation at different levels and forms on sensory evaluation and quality parameters of broiler meat
|Sensory evaluation||Meat quality|
|Treatment groups||Appearance||Flavour||Texture||Juiciness*||Mouth coating||Over all acceptability||Meat pH||Cooking loss (%)||Shear force value (kg of force/cm2)||Water holding capacity (%)|
|Control diet without AB (C)||6.6 ± 0.2||6.6 ± 0.2||6.8 ± 0.1||6.5 abc ± 0.2||6.5 ± 0.2||6.5 ± 0.2||5.8 ± 0.09||22.5 ± 1.8||1.0 ± 0.09||61.3 ± 1.5|
|C + AB (50 ppm)||6.1 ± 0.3||6.5 ± 0.1||6.5 ± 0.2||6.5 bc ± 0.2||6.5 ± 0.2||6.5 ± 0.1||5.9 ± 0.08||22.9 ± 1.1||1.2 ± 0.05||62.1 ± 0.8|
|C + 0.09 % CSB||6.3 ± 0.4||6.8 ± 0.1||6.5 ± 0.2||5.7 a ± 0.3||6.0 ± 0.4||6.2 ± 0.2||5.8 ± 0.08||22.9 ± 0.6||0.9 ± 0.06||59.0 ± 6.7|
|C + 0.18% CSB||6.3 ± 0.3||6.5 ± 0.2||6.4 ± 0.3||6.9 c ± 0.0||6.6 ± 0.2||6.4 ± 0.2||5.8 ± 0.14||22.0 ± 0.6||1.1 ± 0.08||61.0 ± 4.8|
|C + 0.03 % UCSB||5.8 ± 0.6||5.8 ± 0.4||5.8 ± 0.1||6.0 ab ± 0.0||6.3 ± 0.2||5.7 ± 0.1||5.6 ± 0.19||23.6 ± 1.4||1.0 ± 0.03||62.3 ± 2.2|
|C + 0.06 % UCSB||6.5 ± 0.2||6.5 ± 0.2||5.9 ± 0.4||5.8 ab ± 0.4||6.0 ± 0.4||5.7 ± 0.3||5.8 ± 0.02||23.6 ± 1.6||1.0 ± 0.13||61.5 ± 2.6|
AB = Antibiotic (Antibiotic used was oxytetracycline), CSB = Coated Sodium Butyrate, UCSB = Uncoated Sodium Butyrate
Sodium butyrate supplementation to broiler chicken did not greatly alter the serum biochemical parameters indicating that sodium butyrate does not produce any harm to liver and kidney. The meat quality was not altered due to sodium butyrate supplementation. In fact, there was a reduction of serum total cholesterol and LDL cholesterol levels due to supplementation of coated sodium butyrate indicating the production of healthy chicken meat.