An experiment was conducted for 112 days (4 periods) on 5280 number of 37 weeks old layer birds (WL-BV300) to determine the effect of α-galactosidase supplementation to guar (Cyamopsis tetragonoloba) meal (GM) based diets on egg production (EP), feed intake (FI), feed efficiency (FE), egg weight (EW) and egg quality parameters like egg density, egg breaking strength, haugh unit score, shell weight and shell thickness. Six experimental diets (each treatment has 880 birds at 10 replicates of 88 birds in each) were prepared having 3% GM (3GMC), 3% GM with α-galactosidase (3GMCE), 3% GM low (100 kcal/kg) energy (3GMB), 3GMB with α-galactosidase enzyme (3GMBE), 6% GM (6GM) and 6% GM with α-galactosidase (6GME). Results of the experiment did not shown the effect (P>0.05) on EP, FI, FE and egg quality parameters on α-galactosidase enzyme addition except EW shown improved on addition of enzyme to the low energy diet which is in between the 3GMC and 3GMBgroups. Supplementation of α-galactosidase (2 IU/kg diet) enzyme to toasted GM based diets did not significantly affect production performance in layers but a trend of improvement was observed and no significant difference (P>0.05) was observed on egg density, Haugh unit score, shell weight and shell thickness.
Guar (Cyamopsis tetragonoloba) plant is an annual legume growing in many parts of India and leading producer of the world. It was primarily used as bean vegetable for human and as thickening agent in the ice creams, cheeses and pharmaceutical industries because of presence of galactomannan gum in their seeds. Guar meal (GM) is the byproduct of guar gum industry and total annual production of GM in India is 1.97 million tons (NRRA, 2014). Most of GM is used as protein source in the rations of livestock and poultry since GM contains high protein (48.6%) (Rama Rao et al., 2015). About 88% of the nitrogen content is in the form of true protein that makes it as a potential feed ingredient for poultry (Lee et al., 2005). The major antinutritional factor in GM is guar gum a “galactomannan”. It is a polymer of D-mannose linked -1,4 with D-galactose attached to alternate mannose units and galactomannan gum content in the GM was 46g/kg in which mannans is 20 and galactans 22g/kg (Rama Rao et al., 2015). Presence of guar gum residue in GM had negative effects on bird performance by increasing the viscosity of digesta, thereby decreasing growth and feed efficiency, thus limiting the utilization of GM in the rations of poultry. Despite of these deleterious effects the guar meal is relatively inexpensive and have good source of essential amino acids (Ramakrishnan, 1957). GM inclusion levels in the rations can be increased after subjecting the meal with different heat treatments. Enzyme added in the diet breaks the polymeric chain of fibrous material more effectively, thereby reducing the gut viscosity and improves their nutritive value of the meal (Smith and Annison, 1996). Inclusion of NSP Hemicell (mannanase) enzyme reduces intestinal viscosity and increases growth and feed efficiency (Lee et al., 2003b). The negative effects of feeding of guar meal like increased viscosity of digesta, decreased nutrient utilisation can be minimized by supplementing mannanase, glucanase, xylanase and protease enzymes in GM based diets (Rama Rao et al.,2014), which increased the utilization of non-starch polysaccharides in the diet. Using enzymes in poultry diet not only enhance bird performance and feed conversion rate, but also reduce environmental pollution due to reduced excretion of nutrients. Therefore, an experiment was carried out to determine the effect of supplementation of α-galactosidase to the guar meal based diets on production and egg quality performance.
Materials and Methods
The experiment was conducted at Sri Lakshmi Narasimha R&D Layer Farm, Bibinagar, Nalgonda, Telangana State, India. 5280 commercial layers (WL-BV 300) of 37 week old having uniform body weight and egg production, which were randomly distributed in to six experimental groups with 10 replicates (88 birds in each) per group. The layers were fed respective diets for four laying periods (each period 28 days). Eggs produced by each replicate were collected on the daily basis and the mean egg production was calculated by dividing the total number of eggs produced by number of hen days for every period. Daily feed intake was calculated (feed intake in 28 days). Egg weight was recorded period wise from each replicate and eggs laid during last three consecutive days of every period were collected to assess the egg quality parameters. Six experimental diets were formulated (Table 1). Toasted guar meal (GM) was incorporated at 3 and 6% in layer diets of 3GMC and 6GM, respectively. Both diets were supplemented with 2 IU of α-galactosidase per kg diet (3GMCE and 6GME, respectively). A diet with 3% GM having 100 kcal less ME per kg was prepared by altering the levels of DORB and maize (3GMB). The low ME basal diet was fed with 2 IU of α-galactosidase (3GMBE). Enzyme procured from commercial source. Enzyme product was added @ 220g/tonne (8units/g) complete feed which contributed 2U of the enzyme per kg diet.
Table 1: Ingredient and nutrient composition (%) of experiment diets
|Ingredients||3GMC (KG)||3GMCE(KG)||3GMB (KG)||3GMBE (KG)||6GM (KG)||6GME (KG)|
|Soya DOC 45%||17.98||17.98||16.26||16.26||14.74||14.74|
|De-oiled Rice Bran||11.12||11.12||20.05||20.05||10.98||10.98|
|L- Lysine HCL||0||0||0||0||0.01||0.01|
|Trace Mineral Mixture1||0.1||0.1||0.1||0.1||0.1||0.1|
|Choline Chloride 75%||0.05||0.05||0.05||0.05||0.05||0.05|
|Available Phosphorus (%)||0.36||0.36||0.36||0.36||0.36||0.36|
Trace mineral mix1 provided per kg diet: manganese, 120mg; Zinc, 80mg; Iron, 25mg; Copper,10mg; Iodine, 1mg and Selenium, 0.1mg.Vitamin premix2 provided per kg diet: Vitamin A, 20000IU; Vitamin D3, 3000IU; Vitamin E, 10mg; Vitamin K, 2mg; Riboflavin, 25mg; Vitamin B1, 1mg; Vitamin B6, 2mg; Vitamin B12, 40mcg and Niacin, 15mg.*Calculated values
The birds were housed by packing 4 birds in colony cages (18x17x15inch). The experiment was conducted in well ventilated raised platforms 4-bird cage layer house. All replicate groups of layers were offered the respective diets adlibitum. Clean and fresh drinking water provided adlibitum throughout the experimental period. The parameters studied were egg production (EP), feed consumption (FI), feed efficiency(FE), egg weight (EW), egg density (ED), HU score (HU), shell weight(SW) and shell thickness(ST).
The data were analyzed using General Linear Model procedure of Statistical Package for Social Sciences (SPSS) 15th version and comparison of means was done using Duncans multiple range test (Duncan, 1955) and significance was considered at P<0.05.
Results and Discussion
The average EP of layers fed different experimental diets observed significant difference (P<0.05) with lowest EP in birds fed low energy diets in both with or without α-galactosidase enzyme (3GMB and 3GMBE) supplementation and other four diets (3GMC, 3GMCE, 6GM,6GME) didn’t shown any significant difference (Table 2). In general, supplementation of enzyme to the diets showed numerical improvement (0.56 to 0.80%) in EP, though the differences were not statistically significant (P>0.05). Supplementation of enzyme to low energy diets (3GMB and 3GMBE) did not exert beneficial effects. However, EP was significantly reduced in the low ME diets (3GMB or 3GMBE). These results are in agreement with findings of Gunawardana et al.(2009) reported that supplementation of xylanase and β-glucanase included at 0.05% level to different dietary energy level 2791, 2857, 2923 and 2989 kcal of ME/kg and protein levels 15.5 and 16.15. Hens fed with low dietary energy with enzyme supplementation showed decreased egg production compared to high energy diets. The results of current study and others (Chong et al.,2008) showed an improvement of 0.5 to 0.8% in EP compared to the respective groups fed the diets with or without enzyme supplementation. A marginal improvement of 0.5% is equal to an increase of 45 eggs per ton of feed considering 110g as feed intake per bird per day. However, the decision of using enzymes may depend on the cost benefit ratio of enzymes supplementation; irrespective the significant difference observed between groups fed with or without enzyme supplementation. Hypothesis of this experiment was to look at possible benefits of α-galactosidase supplementation to diets containing two levels of high fibre alternate protein source (GM). Incorporation of GM particularly at higher level i.e. 6% in diet was expected to reduce the EP due to presence of higher concentration of NSP. Thereby enzyme supplementation was hypothesized to improve the digestibility of NSP component and eventually improve the EP beyond the un-supplemented GM based diets. However, the layer performance was unaffected with inclusion of GM at the highest level (6%). Similarly, Rama Rao et al. (2015) reported no significant difference in EP due to incorporation of toasted GM up to 10% compare to those fed with corn-soybean based diet. As there was no negative effect of GM inclusion (up to 6%), the EP could not be improved further with α-galactosidase supplementation to the GM based diets.
FI was not affected by reduction in ME (100 kcal/kg) in 3GMB compared to 3GMC (Table 2), which is contrary to the general principle, there is a progressive increase in feed intake with reduction in dietary ME level is expected (Rama Rao et al., 2014). The lack of response in FI might be due to either age of the bird, body weight and or static gut capacity. Alteration in FI with dietary ME concentration is largely noticed in broiler or layer chicks. The GI tract volume or capacity is in dynamic mode in growing birds, while in mature birds, the intestinal capacity is fixed and flexibility in gut volume is very limited. Therefore, dietary variation and nutrient concentration influenced the FI in growing birds but not in mature laying hens. Overall FE was lower in basal diets (3GMB or 3GMBE) compared to 3GMC, 3GMCE, 6GM or 6GME (Table 2). The α-galactosidase supplementation had no effect on FCR at either of energy levels in the present study. Waldroup (2006) concluded that supplementation of α-galactosidase did not affect the FCR in broilers fed with corn soybean diets. Ehsani and Torki (2010) reported dietary inclusion GM with β-mannanase increased FCR in laying hens compared to the hens fed the control diets. Abdulmohsen (2014) reported inclusion of GM up to 10% in laying hens did not show significant (P>0.05) effect on FCR. Kamran et al. (2002) reported that supplementation of commercial enzyme (Natugrain) to the GM based diets significantly (P<0.05) increased FCR in broiler diets. Novak et al. (2008) observed no effect of dietary energy concentration on FCR, where as enzyme supplementation had a negative effect on FCR. But, Ramesh and Chandrasekaran (2011) and Sharma and Katoch (1993) reported better FE due to supplementation of enzyme to low energy diets. Supplementation of α-galactosidase to corn soybean diets did not affect the feed efficiency in broilers (Wang et al., 2010).
Table 2: Mean values of egg production, feed intake, feed efficiency and egg weight in layers (37- 52 week of age) fed with and without α- galactosidase enzyme in GM based diets
a, b,c means with different superscripts in a column differ significantly (P<0.05)
Overall experiment data indicated significance (P<0.05) reduction in EW in layers fed low ME basal diet (3GMB) (Table 2). Enzyme supplementation to the group improved the EW which is in between the 3GMC and 3GMBgroups.The present results are similar to Gunawardhana et al.(2009) who reported that, supplementation of Rovabio (a cock tail of xylanase, amylase and protease) to corn soya diet had significantly improved egg weight. However, Rama Rao et al. (2014) reported comparable egg weights were observed in layers fed different energy concentration without any enzyme supplementation. Wu et al. (2005) reported that, increasing dietary energy without the increase of other nutrients (protein and amino acid) levels did not improve egg weight and both dietary energy and protein are important to optimize egg weight which is contrary to the present findings. Dietary supplementation of α-galactosidase to the GM based diets did not influenced (P>0.05) the ED during overall experimental period (Table 3). These results were in accordance with the values of Rama Rao et al. (2015), who reported dietary inclusion of GM up to 15% did not affected the egg density.
Table 3: Mean values of egg density, Haugh unit, shell weight and shell thickness in layers (37-52 week of age) fed with and without α- galactosidase enzyme in guar meal based diets
|Treatment Group||Egg Density||HU||Shell wt(g)||Shell Thickness(mm)|
Addition of α-galactosidase enzyme at any of the dietary energy concentration had no effect (Table 3) on HU (quality of egg albumin). These results are corroborative with the results of Ehsani and Torki (2010) who reported that the layers fed β-mannanase to GM based diets did not effect on HU score. Similarly, Rama Rao et al. (2015) observed no significance difference in HU score in layers fed toasted GM up to 15% in corn soy based diets. Novak et al. (2008) who reported no effect of dietary energy or protein supplemented with or without cocktail enzyme (800, 8000 and 1600 u/g amylase, protease and xylanase, respectively) but results are contrary to Shahbazi (2012) who reported that interaction between GM and β-mannanase has significantly influenced the Haugh unit score. Inclusion of α-galactosidase to the basal diets and control diets had comparable (P>0.05) SW and ST (Table 3). These findings are in line with Ehsani and Torki (2010) and Shahbazi (2012) who reported non-significant effect of supplementation of β-mannanase to GM based diet on shell weight. Rama Rao et al. (2015) also reported no significant difference in shell weight when birds fed diet with toasted GM up to 15%.
Based on the results of the present study, it is concluded that, supplementation of α-galactosidase (2 IU/kg diet) to the toasted GM based diets did not significantly affect production performances in layers but a trend of improvement was observed by supplementation of enzyme.