Effect of Dietary Supplementation of Aspergillus Xylanase on Broiler Chickens Performance

Document Type: Research Articles

Authors

1 Department of Livestock and Pasture Science, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa

2 Department of Animal Science, Faculty of Agriculture and Natural Science, University of Mpumalanga, Private Bag X11283, Mbombela 1200, South Africa

3 Department of Animal Science, School of Agricultural Science, North-West University, Private Bag X2046, Mmabatho 2735, South Africa

Abstract

The effect of Aspergillus xylanase (ASXYL) supplementation to maize-soybean diets on serum aspartate aminotransferase, serum alanine aminotransferase, microbial examination, growth traits, carcass characteristics and meat quality traits of broiler chickens was investigated. Three hundred one-day-old mixed sex “Cobb 500” broiler chicks were allotted to 5 dietary treatments with 5 replicates of 12 birds each. The treatments include, ASXYL0 (0 g/kg), ASXYL10 (1 g/kg), ASXYL15 (1.5 g/kg), ASXYL20 (2 g/kg) and ASXYL25 (2.5 g/kg). Birds fed ASXYL20 had the highest (P<0.05) body weight with an improved feed conversion ratio (FCR) and a higher values for thigh, breast, wing and carcass yields. Neck weight was high (P<0.05) for fed birds ASXYL0, ASXYL15 and ASXYL20. Drumstick recorded higher (P<0.05) value for birds fed ASXYL20 though, similar to ASXYL10, ASXYL15 and ASXYL25. Drip and cooking loss decreased (P<0.05) with increased supplemental levels of ASXY while shear force increased (P<0.05) as ASXYL supplementation increased. Urea, aspartate aminotransferase and alanine aminotransferase decreased (P<0.05) with increased supplemental levels of ASXYL while glucose level increased (P<0.05) with increased levels of ASXYL supplementation. Supplementary ASXYL influenced (P<0.05) the proliferation of Lactobacillus counts in ileum and caecum while no difference (P>0.05) was observed on the population of Bifidobacteria and Escherichia coli in both ileum and caecum of broilers at the end of the feeding trial. It was concluded that dietary ASXYL20 produced a much improved body weight and retail cut yields. Again, the bio-markers showed that ASXYLimproved the health status of broiler chicken and the tested enzyme influenced a positive intestinal environment.

Keywords


INTRODUCTION

Poultry farming is one of the most important sectors in the global agribusiness. This sector increased significantly after inclusion in the production chain in the 1980 s mainly as a result of increased adoption of technology in the sector. The mechanisms of technological advances in nutrition with the inclusion of exogenous enzymes in broiler diets allow greater assimilation of nutrients resulting in increased meat yield as a result of improved body weight. Research studies have reported the beneficial impact of exogenous xylanase enzymes on the performance and nutrient digestibility of broiler birds fed non-conventional feedstuffs (Mathlouthi et al. 2002; Oyeagu et al. 2016). Broiler ration in South Africa and most part of the world are almost entirely formulated from two basic ingredients; maize, which is an excellent energy source and soybean meal, which contributes a high-quality protein and with great amino acid availability (Opalinski et al. 2006). However, it is known that the nutrients originated from these ingredients are not absorbed properly, mainly due to the presence of anti-nutritional factors such as non-starch polysaccharides (NSPs) which are inherent in the plant cell wall (Oyeagu et al. 2015). Due to the chemical structure of the plant cell wall matrix, NSPs degrading enzymes has been recommended to enhance poultry performance. Exogenous xylanase enzyme supplementation has been documented to be effective in breaking polymeric chains of NSPs and hence improve the nutritive value of feedstuffs (Giraldo et al. 2008). Therefore adding NSPs – degrading enzymes in poultry diet has increased considerably in recent years. Birds do not produce enzymes such as xylanase for the digestion of NSPs. Supplementation of xylanase enzymes may not only reduce the anti-nutritive effects of NSPs, but also releases some nutrients from these, which could be utilized by birds (Oyeagu et al. 2016). Again, these NSPs – degrading enzymes has been reported to improve Lactobacillus and Bifidobacteria counts in caecum of broilers fed corn-soybean meal based diet (Nian et al. 2011). Exogenous xylanase enzyme supplementation can change the nutritional status which may regulate the metabolism and functioning of the growth related endocrine system that will improve carcass yield of broiler chickens (Hajati et al. 2009). Nutritional status is an important factor in the regulation of plasma biomarkers in broiler chickens (Buyse et al. 2002; Swennen et al. 2005; Gao et al. 2008). Evaluation of plasma biochemistry in birds allows for the identification of metabolic alterations as a result of management conditions such as diets (Alonso-Alvarez and Ferrer, 2001). The use of blood examination as a way of assessing the health status of animals has been documented (Muhammed et al. 2000; Owoyele et al. 2003). Haematobiochemical examination plays a vital role in the physiological, nutritional and pathological status of organisms (Muhammed et al. 2000). They range from giving the level of the blood to detecting ailment or disorders through them. It had been reported that biochemical changes as a result of toxins have effects on blood parameters (Karnish, 2003). The effect of different diets (barley-based, wheat-based, and non-conventional feed) supplemented with different mono-enzymes or multi-enzymes has been evaluated on the blood parameters of broiler (Muhammed et al. 2000; Owoyele et al. 2003; Oyeagu et al. 2016; Oyeagu et al. 2019a), but there is little information on serum biomarkers, ileum and caecal micro-flora, carcass characteristics and meat quality traits of broiler chickens fed Aspergillus xylanase. The present study, therefore, sought to examine the effect of Aspergillus xylanase on serum biomarkers, ileum and caecal micro-flora, growth traits, carcass characteristics and meat quality traits in broiler chickens fed maize-soybean meal diets.

 

MATERIALS AND METHODS

Ethical consideration

Ethical principles were taken into consideration during the study to adhere to the national and international standards governing research of this nature with regards to the use of research animals. Ethical approval was obtained from the Ethical Clearance Committee of University of Fort Hare, Alice, South Africa.

 

Study site

This study was conducted at the poultry unit of North-West University experimental farm (Molelwane), in the North West province of South Africa. The study area is located at 25.80˚ S and 25.50˚ E and experiences summer climate from August to March with temperatures ranging from 22 to 35 ˚C and average annual rainfall ranging from 200 to 450 mm per annum. The study site experiences winter from May to July, with sunny dry days and cool nights with average minimum and maximum temperatures of 2 and 20 ˚C, respectively. The study lasted for six weeks.

 

Enzyme characteristics

The tested Aspergillus xylanase enzyme (RONOZYME® WX (CT), DSM Nutritional Products Johannesburg South Africa) is a granulated heat stable endo-xylanase. The active substance in the enzyme is endo-1, 4-β-xylanase (IUB No. 3.2.1.8) which is produced by a genetically modified strain of Aspergillus oryzae micro-organism (Aquilina, 2016). This strain is deposited at the German Collection of Microorganisms and Cell Cultures (DSMZ) with the accession number DSM 26372 (Aquilina, 2010b). According to the manufacturer (Aquilina, 2010a), the bulk density is approximately 1.1 g/ml and the average particle size is approximately 600 µm with enzyme activity of 1000 FXU/t (1000 g/t).

 

Experimental diets

The feeding strategy consisted of starter (0 to 21 d) and finisher (22 to 42 d) basal diets (Tables 1 and 2), which were formulated to meet the birds’ dietary nutrient requirements (NRC, 1994). At each feeding phase (starter and finisher), five dietary treatments of iso-nitrogenous and iso-caloric were formulated through the addition of Aspergillus xylanase (ASXYL) enzyme at five different levels.

 

Table 1 Ingredient (%) and chemical composition (g/kg DM unless otherwise stated) of experimental diets for broiler chicks at the starter phase (0-3 weeks)

 

ASXYL0: basal diet (without Aspergillus xylanase (XYL)); ASXYL10: basal diet + 1 g XYL/kg feed; ASXYL15: basal diet + 1.5 g XYL/kg feed; ASXYL20: basal diet + 2 g XYL/kg feed and ASXYL25: basal diet + 2.5 g XYL/kg feed.

1 Vitamin and mineral premix (2.5 kg of vitamin premix) contained: Retinal: 2700 mg; Calcidiol: 400 mg; Tocopheryl acetate: 18 g; Menadione: 2000 mg; Thiamine: 1800 mg; Riboflavin: 6600 mg; Niacin: 10 g; Calcium pantothenate: 30 g; Pyridoxine: 3 g; folic acid: 1 g; Cobalamin: 15 mg; Choline chloride: 250 g; Biotin: 100 mg; Mn: 100 g; Fe: 50 g; Zn: 100 g; Cu: 10 g; I: 1 g and Se: 200 mg.

2 1000 g of Maxiban contained: Narasin: 80 g/kg and Nicarbazin: 80 g/kg.

3 1000g of Surmax contained: Avilamycin: 100 g/kg.

 

The five experimental diets formulated were, ASXYL0 (only basal diet; BD), ASXYL10 (BD+1 g ASXYL/kg feed), ASXYL15 (BD+1.5 g ASXYL/kg feed), ASXYL20 (BD+2 g ASXY/kg feed) and ASXYL25 (BD+2.5 g ASXY/kg feed) for both starter and finisher phases. The ingredient and chemical composition of the five experimental diets for starter and finisher phases are presented in Tables 1 and 2, respectively. The chemical (proximate) composition of the experimental diets was analyzed according to AOAC (2006) methods with average crude protein (CP) and metabolizable energy (ME) of 23.70 CP and 12.60 MJ of ME/kg respectively for starter chicks while an average of 19.70 CP and 13.00 MJ of ME/kg was recorded for finisher birds.

 

Experimental birds and management

A total of three hundred, one day old, non-sexed broiler birds (Cobb 500®) were used in the present study. Sixty birds (five replication of twelve birds in each replicate per treatment group) were assigned randomly to one of the five experimental diets (ASXYL0, ASXYL10, ASXYL15, ASXYL20 and ASXYL25). Each experimental diet was replicated into five experimental pens measuring 2.5 m length × 2.5 m width × 2.5 m height with twelve birds each. The birds were housed in cages with wood shavings as litter. General flock prophylactic management and routine vaccinations were administered as follows; day 1 – intra ocular New castle disease vaccine, week 2 – Gumboro disease vaccine, week 3 – Lasota (New castle disease vaccine), week 4 – Gumboro disease vaccine, and week 5 – fowl pox vaccine. A stress pack was administered to the birds via drinking water at 100 g/50 liters (according to manufacturer’s recommendation) to boost appetite and energy supply. Dietary treatments and clean water were provided ad libitum in a six-week feeding trial.

 

Serum biochemical profile

Before blood collection, birds were feed-fasted for 4 h in an attempt to allow for the stabilization of the various plasma constituents.

 

Table 2 Ingredient (%) and chemical composition (g/kg DM unless otherwise stated) of experimental diets for broilers at the finisher phase (4-6 weeks)

 

ASXYL0: basal diet (without Aspergillus xylanase (XYL)); ASXYL10: basal diet + 1 g XYL/kg feed; ASXYL15: basal diet + 1.5 g XYL/kg feed; ASXYL20: basal diet + 2 g XYL/kg feed and ASXYL25: basal diet + 2.5 g XYL/kg feed.

1 Vitamin and mineral premix (2.5 kg of vitamin premix) contained: Retinal: 2700 mg; Calcidiol: 400 mg; Tocopheryl acetate: 18 g; Menadione: 2000 mg; Thiamine: 1800 mg; Riboflavin: 6600 mg; Niacin: 10 g; Calcium pantothenate: 30 g; Pyridoxine: 3 g; folic acid: 1 g; Cobalamin: 15 mg; Choline chloride: 250 g; Biotin: 100 mg; Mn: 100 g; Fe: 50 g; Zn: 100 g; Cu: 10 g; I: 1 g and Se: 200 mg.

2 1000 g of Maxiban contained: Narasin: 80 g/kg and Nicarbazin: 80 g/kg.

3 1000g of Surmax contained: Avilamycin: 100 g/kg.

 

Blood was collected in the morning to further reduce the variability of the measured plasma constituents. At 42 days of age, five birds were chosen randomly from each experimental pen and 2 mL of blood was collected from the wing vein using a sterile syringe and needles. Blood collected was emptied into a labelled treated vacutainer tubes. Red-top tubes without anticoagulant were used for serum biochemical analysis. The blood was stored for 10 minutes at room temperature. After centrifugation (20 minutes, 1500 rpm), the serum was collected into 0.5 mL centrifuge tube and stored at -20 ˚C pending determination of serum metabolites. All analyses were conducted within 48 h after collection. The serum metabolites considered are alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total protein, albumin, urea and cholesterol were assayed using automated Idexx Vet Test Chemistry Analyser (IDEXX Laboratories, Inc) in the Animal Health Laboratory at the Centre for Animal Health Studies North-West University, Marfikeng.

 

Growth performance

Average daily feed intake (ADFI) per bird was measured from day 1 to day 42 of age by subtracting the weight of the feed left over from that of the feed offered, and dividing the difference by the total number of birds in the pen. Average live-weight was measured weekly by weighing all the birds in each pen using a 10100 g capacity precision weighing balance with model, A and D Weighing GF-10 K industrial balance, made in Japan. The feed conversion ratio (FCR) was calculated as follows: FCR= feed intake/weight gain.

 

Slaughter procedure

At 42 days of age, all chickens were taken to Rooigrond poultry abattoir (North-West province, South Africa) for slaughter. The chickens were starved for 12 hours before slaughter. All the chickens were humanely gas stunned by exposing them to relatively low concentrations of carbon dioxide (<40% by volume in air), and then, once they were unconscious, exposed to a higher concentration (approximately 80% to 90% by volume in air). At the abattoir, all the chickens were hung onto a movable metal rack that holds them upside down by their feet. Chickens were then slaughtered by cutting the jugular vein with a sharp knife and they were left hanging until bleeding stopped.

 

Carcass characteristics

Five birds per replicate were randomly selected for determination of carcass characteristics and meat quality. Immediately after slaughter, the feathers were plucked and the gastro intestinal tract (GIT) was removed. The carcasses were then weighed to obtain the carcass weight of the birds. For the measurement of carcass cuts, head and shanks were removed close to the scull and at hock joint, respectively. Wings were removed by cutting at the humeoscapular joint, the cuts were made through the head to the shoulder girdle, and the vertebrae was then removed intact by pulling outwardly. The breast muscle, neck, wings, shank, thighs, drumsticks and vertebrae (back) were each weighed separately.

 

Meat pH and temperature measurements

Meat pH and temperature were recorded immediately after slaughter and 24 h post slaughter on the breast muscle (central area of the breast) using a Corning Model 4 pH-temperature meter (Corning Glass Works, Medfield, MA) equipped with an Ingold spear-type electrode (Ingold Messtechnik AG, Udorf, Switzerland) according to Stanford et al. (2003). After every 20 measurements, the pH meter was calibrated with pH 4, pH 7 and pH 10 standard solutions (Ingold Messtechnik AG, Udorf, Switzerland).

 

Meat colour

Colour of the meat (L*=Lightness, a*=Redness and b*=Yellowness) was determined 24 hours after slaughter, using a Minolta colour-guide (BYK-Gardener GmbH, Geretsried, Germany), on a 20 mm diameter measurement area and illuminant D65-day light, 10 degree observation angle. The colour meter was calibrated using the green standard before measurements. Colour recording was done on the surface of the breastmuscle, which was allowed to bloom for 1 hour on a polystyrene tray at 4 ˚C.

 

Water holding capacity (WHC)

The pressure method as described by Delezie et al. (2007) was used to determine the WHC. About 100 g meat sample from pectoral major (PM) was cut and weighed to obtain the initial weight using a digital scale sensitive up to 0.01 g. The meat sample was then placed in between 2 filter papers, placed on a flat surface and approximately 60 kg weight was applied on the sample for 5 min. Thereafter, the meat sample was re-weighed. The WHC was calculated as the ratio of the amount of water retained over the initial sample weight.

 

Drip loss

Approximately 30 g meat strips were sampled from the breast muscle parallel to the fibre direction then weighed to get the wet sample using a digital scale sensitive to 0.01 g. The samples were suspended inside a plastic container and sealed under atmospheric pressure. The samples were then held at 2 ˚C for 72 hours after which they were removed from the container. The samples were blotted with paper towels to remove excess surface moisture and were then re-weighed. The drip loss was then calculated by subtracting the blotted sample weight from the initial sample weight. The drip loss was expressed as a percentage of the initial sample weight (Honikel and Hamm, 1994).

 

Cooking loss measurement

Raw meat cubes were cut from the breast muscle, weighed in natura, then placed in a plastic bag and cooked in a water bath at 75 ˚C for 45 minutes (Rizz et al. 2007). The samples were then cooled in running water for 15 min, dried with soft tissue and weighed (Sanka and Mbaga, 2014). Cooking loss was calculated as percentage loss of weight during cooking relative to the weight of raw muscle (Petracci and Baéza, 2009) according to the following formula:

Cooking loss (%)= ((weight before cooking–weight after cooking)/(weight before cooking)) × 100

 

Tenderness

Breast muscles were wrapped in aluminum foil and baked to reach an internal temperature of 85 ˚C, which was maintained for 30 minutes. Warner Bratzler shear device mounted on an Universal Instron apparatus (cross head speed=200 mm/minute, one shear in the centre of each core). Smaller samples were then cut parallel to the muscle fibres with the aid of a Meullenet - Owens Razor Shear Blade (A/MORS) with a diameter of 1.2 cm. The reported value represented the average peak force measurements of each sample in Newtons. The shear force was recorded using the Texture analyser (TA XT plus).

 

Cecal and ileum micro flora composition

Five birds per treatment at the age of 42 days were killed by severing the jugular vein. The abdominal cavity was opened, and the entire gastro intestinal tract was removed aseptically. All digesta contents of ileum, caecum and colon were collected immediately under aseptic conditions into sterile glass bags and put on ice before they were transported to the laboratory for enumeration of microbial populations. Ceacal and ileum digesta contents were emptied aseptically in a new sterile bag and were immediately diluted 10-fold (ie 10% wt/vol) with sterile ice-cold anoxic PBS (0.1 m; pH 7.0) and subsequently homogenized for 3 min in a stomacher (Bagmixer 100 Minimix, Interscience, Arpents, France). Each ceacal and ileum digesta homogenate was serially diluted from 10-1 to 10-7. Dilutions were subsequently plated on duplicate selective agar media for enumeration of target bacterial groups. In particular, E. Coli, Lactobacillus spp. and Bifidobacterium spp. were enumerated using VRB agar (MERCK, 1.01406), Rogosa agar (MERCK, 1.10660), and Beerens agar respectively according to Tuohy et al. (2002). Plates were incubated at 39 ˚C for 48 to 120 hours anaerobically (Beerens, Rogosa agars) or 24 to 48 hours anaerobically at 37 ˚C (VRB agar). The bacterial colonies were enumerated, and the average number of live bacteria was calculated based on the weight of original ileum and caecum contents. All quantitative data were converted into logarithmic colony forming units (cfu/g), Koc et al. (2010).

 

Statistical design and analysis

Data collected during the study were subjected to analysis of variance (ANOVA) for completely randomized design (CRD) as described by Steel and Torrie (1980)using general linear model Procedure of SAS (2010). The statistical model used to test the effects of treatment on growth traits, meat quality traits, carcass characteristics, serum biochemical profile, and gut micro-flora was:

Yij= µ + Ai + Eij

Where:

Yij: observed value of a dependent variable.

µ: overall mean.

Ai: effect of different levels of dietary Aspergillus xylanase enzyme.

Eij: residual error.

The differences between means were tested for significance at P < 0.05 using least significant difference (LSD) range test.

 

RESULTS AND DISCUSSION

Serum biochemical profile

Table 3 represents the serum biochemical traits of broiler chickens fed different inclusion levels of Aspergillus xylanase (ASXYL). The addition of ASXYL altered (P<0.05) the concentrations of serum glucose, urea and serum enzymes (aspartate aminotransferase (AST) and alanine aminotransferase (ALT) while total protein, cholesterol and alkaline phosphatase (ALP) did not differ (P>0.05). Urea, AST and ALT values decreased (P<0.05) as the levels of ASXYL enzyme increased. Again, glucose level increased (P<0.05) with increased inclusion levels of ASXY enzyme.

 

Gut micro-flora composition

The population of ileum and caecum microbes of broilers fed maize-soybean meal diet with different inclusion levels ofASXYL is presented in Table 4.ASXYL supplementation had no influence (P>0.05) on the population of Bifidobacteria and Escherichia coli in both ileum and caecum of broilers at 42 days of age. However, supplementing ASXYL enzyme increased (P<0.05) the counts of Lactobacillus in the ileum and caecum of broiler birds compared to their counterparts that received XYL0 (control diet) that do not contain Aspergillus xylanase.

 

Growth performance

Different phases in growth performance of broiler birds fed maize-soybean meal based diets supplemented with ASXYL are presented in Table 5. All the growth traits considered in this study were affected (P<0.05) by the inclusion of dietaryASXYL except for body weight gain (BWG) during finisher phase. Birds fed ASXYL20 consumed less feed at starter phase, finisher phase and overall feeding trial when compared with birds fed other levels of ASXYL. Average daily feed intake of birds fed ASXYL20 was lower but similar to birds fed ASXYL25 when compared with other treatments used in the study. Daily weight gain and BWG were highest (P<0.05) for birds fed ASXYL20 during the starter phase and overall phase (entire feeding period) but similar to birds fed ASXYL25. Birds fed ASXYL20 recorded an improved FCR during the starter and the overall feeding period compared with other treatments used in the study.

 

Carcass characteristics of broiler chickens

The meat yield traits of broiler birds fed maize-soybean meal diet with different supplemental levels ofASXYL enzyme is presented in Table 6. The weights of carcass, neck, wing, drumstick, thigh, breast and head were affected (P<0.05) by the addition of ASXYL while shank and vertebrate weights did not differ (P>0.05). Birds fed ASXYL20 had the highest (P<0.05) values for thigh, breast, wing as well as carcass yields compared with birds fed other treatments used in the present study. Neck weight was highest (P<0.05) for ASXYL20 fed birds, though statistically similar to birds fed ASXYL0 and ASXYL15. Drumstick recorded an improved (P<0.05) value for birds fed ASXYL20, though similar to their counterparts that received dietary ASXYL10, ASXYL15 and ASXYL25.

 

Table 3 The effect of dietary Aspergillus xylanase supplementation on serum biochemical (SB) metabolites of broiler birds

 

ASXYL0: basal diet (without Aspergillus xylanase (XYL)); ASXYL10: basal diet + 1 g XYL/kg feed; ASXYL15: basal diet + 1.5 g XYL/kg feed; ASXYL20: basal diet + 2 g XYL/kg feed and ASXYL25: basal diet + 2.5 g XYL/kg feed.

AST: aspartate aminotransferase; ALT: alanine aminotransferase and ALP: alkaline phosphatase.

The means within the same row with at least one common letter, do not have significant difference (P>0.05).

SEM: standard error of the means.

 

Table 4The effect of dietary Aspergillus xylanase supplementation on the counts of bacteria in the ileum and caecum (log10 cfu/g) of broilers fed corn-soybean meal diets

 

ASXYL0: basal diet (without Aspergillus xylanase (XYL)); ASXYL10: basal diet + 1 g XYL/kg feed; ASXYL15: basal diet + 1.5 g XYL/kg feed; ASXYL20: basal diet + 2 g XYL/kg feed and ASXYL25: basal diet + 2.5 g XYL/kg feed.

AST: aspartate aminotransferase; ALT: alanine aminotransferase and ALP: alkaline phosphatase.

The means within the same row with at least one common letter, do not have significant difference (P>0.05).

SEM: standard error of the means.

 

Table 5 The effect of dietary xylanase supplementation on feed intake (FI), weight gain (WG) and feed conversion ratio (FCR) of broiler birds

 

ASXYL0: basal diet (without Aspergillus xylanase (XYL)); ASXYL10: basal diet + 1 g XYL/kg feed; ASXYL15: basal diet + 1.5 g XYL/kg feed; ASXYL20: basal diet + 2 g XYL/kg feed and ASXYL25: basal diet + 2.5 g XYL/kg feed.

The means within the same row with at least one common letter, do not have significant difference (P>0.05).

SEM: standard error of the means.

 

Again, head weight was lowest (P<0.05) for birds fed ASXYL0 and ASXYL25 while those that received ASXYL20 recorded the highest head weight value, though statistically similar to their counterparts that received ASXYL10 and ASXYL15. Generally, birds fed ASXYL20 were observed to have an improved (P<0.05) retail cut yields of neck, wing, drumstick, thigh, breast, head as well as carcass when compared with birds fed other ASXYL levels.

 

Meat quality attributes

The meat quality traits of broiler chickens fed different in clusion levels ofASXY are presented in Table 7. Different levels of ASXYL supplementation to maize-soybean meal diet had an influence (P<0.05) on cooking loss, shear force and drip loss while colour, water holding capacity, pHo, pHu and temperature were not affected (P>0.05). Cooking loss value of chicken breast meat was significantly (P<0.05) higher for birds fed ASXYL0, though similar to their counterparts that received ASXYL10. The cooking loss of chicken breast meat recorded the lowest (P<0.05) value for birds fed higher levels of the tested enzyme (ASXYL15, ASXYL20 and ASXYL25). Shear force values of the breast meat increased (P<0.05) as the levels of the tested enzyme increased. The lowest (P<0.05) shear force value was recorded for control birds (ASXYL0) while ASXYL15, ASXYL20 and ASXYL25 fed birds had the highest (P<0.05) shear force values, though similar to birds fed ASXYL10. The addition of ASXYL enzyme influenced (P<0.05) the reduction of drip loss value, whereas the breast meat of birds fed ASXYL0 and ASXYL10 had the highest (P<0.05) values of drip loss, though statistically similar to their counterparts that received ASXYL15. The lowest (P<0.05) drip loss value was recorded for birds fed ASXYL20 and AS XYL25.

 

Serum biochemical profile

Blood biochemical parameters can reflect the physiological state of the body. In the present study, we observed that broilers had a higher concentration of blood glucose with increased supplemental levels ofASXYL. Shouqing et al. (2015) opined that lactose can be degraded into glucose and galactose by lactase which is mainly synthesized and secreted by the small intestine epithelia cells of piglets. In mammals, glucose is not the only host energy sources, but it promotes the development of brain and neuron, again, excess of the glucose is deposited in the tissue (flesh), hence, developing the retail cut yields (Bano, 2013). The result of the present study did not conform to those of Balamurgan and Chandrasekaran (2010), who found no effect of supplemental multi-enzyme (xylanase and protease) in blood glucose of broiler birds. Chauhan et al. (2002) found that no effect was detec