The experiment that was done in Department of Animal and Food Sciences, University of Kentucky, and the Alltech-University of Kentucky Nutrition Research Alliance, Lexington used broiler chicks as the monitoring material where poultry diets are supplied in three different ways that are; diet is added with α-galactosidase; diet is added with acid (for acidification); and diet is added with both. The objective of this research was to examine the effects of α-galactosidase and acidification of diets on nutrient digestibility and growth performance of broiler chicks. Thus on this assay of digestibility and growth performance observation, two experiments were done to monitor the differences. The two experimental procedures will be discussed later. In the conclusion, acidification improves the efficacy of α-galactosidase. In short, both factors (enzyme and acid) generally help to digest or hydrolyze substrate into smaller subunits, which in turn, improve nutrient retention of growth performance.
so I hope after reading this abstract you guys might have a clear overall picture about this investigation.....I'd summarized the procedures of the experiment but for more detail you guys can find it online by typing the same tittle as shown above...
Housing of the birds started at the age of 1 day old. The environment was controlled their parameters of the temperature, light supply and feeding method. The temperature was maintained at 310C at the first week then lowered to 27oC throughout the study. The light supplied 22 hours per day and all chicks were fed ad libitum. Note; if a bird died at first 4 day, it’ll be replaced with similar conditions (weight, fed etc.). 88% of energy level on normal basal diets was used to feed the chicks. The chemicals or materials used were the α-galactosidase extracted from commercial fungus with measured activity was 1724 units per gram (GaIU). For acidification, the food-grade anhydrous citric acid was used (from Roche Vitamins Inc). An additional chemical; Chromic oxide was used purchased from Fisher Scientific Inc. two experiments were done in different ways, both to monitor the nutrients digestibility and growth performance.
In experiment I, a total of 140 broiler chicks were housed, all fed with; low energy level basal diets; basal diets with 2% citric acid; basal diets with 0.1% α-galactosidase; or basal diets with both reagents. At day 14, the excreta were collected for analysis.
In experiment II, a total of 576 chicks were assigned with 8 treatments lasted for 3 weeks. The treatment structure consisted a factorial arrangement of 2 X 2 X 2; with 2 energy level (low or normal); 2 level citric acid (0 or 1.5%); and 2 α-galactosidase level (0 or 0.1%) where citric acid and α-galactosidase were added in equivalent amounts of corn in basal diet. The excreta collected at day 18 whereas 6 random birds from each treatment were selected to collect their excreta at day 22 (total = 48 birds). Then the birds were fed for 20 minutes only. 30 minutes after feeding, 3 birds from each treatment were killed by asphyxiation with argon gas followed by cervical dislocation. Digesta were collected and determined its pH. Another sample digesta were collected from the remaining 3 birds from each treatment 60 minutes after fed. All digesta samples were stored at 20oC.
The laboratory analyses included 7 determination that are; Dry matter (AOAC, 1995); Gross Energy, GE (heat combustion Parr 1281 Oxygen Bomb Calorimeter); Nitrogen content (Dumas methodology 990.03; AOAC, 1995); Neutral detergent fiber, NDF (Van Soest, 1967); Chromium content (from Cr2O3 by Williams et al., 1962); pH (Radcliffic et al., 1998); reducing sugar (Miller, 1959).
From the result table (table 1 in the journal with correspond title) these index percentages are obtained by comparing the margin of weight gain and retention of DM, CP, NDF, and AMEn with the correspond set of experiment for example; the set with basal diets + 0.1% Gal and “-“CA is compared with basal diets + 0% Gal and “-“CA without any concern on the CA.
Table I the summary of experimental analysis for experiment I
| Treatment (%) | Weight Gain (g/bird) | Retention |
| GAL | CA | Day 1 – 14 | Day 1 – 21 | DM | CP | NDF | AMEn |
| 0.1 | - | +4.7% | +6.8% | +0.9% | +3.2% | +26% | +1.6% |
| - | 2 | -9.8% | -9.8% | +2.6% | +3.4% | +34% | +1.6% |
| 0.1 | 2 | -4.7% | -2.1% | +3.4% | +6.7% | +49% | +3.2% |
With addition of 0.1% GAL, the weight gained were the highest (780 and 766 g/birds) that was constantly increased from day 1 to day 21. The more CA is added, the more weight is not gained. Even though there are a little decrease in weight gain for the combination of GAL and CA, however both increase the retention of nutrients digestibility. There was a significant interaction between α-galactosidase and citric acid for the increase of body weight, AMEn, CP, NDF and DM.
Table II the summary of experimental analysis for experiment II
| Supplementation | α-galactosidase | Citric acid |
| pH | Not significant | Increased from 5.4 to 6.2 |
| Reducing sugar | Increased 34% to 13.1 g Kg-1 from 8.6 g Kg-1 | Increased 31% to 12.5 g Kg-1 from 8.6 g Kg-1 |
During this experiment, two energy levels were observed that were low and normal. The result obtained shown when feeding chicks with low energy level gives the following analysis (compared with normal energy level)
| Parameters | Index (changes) |
| Weight (g/bird) | -15.6% |
| Feed intake (g/bird) | +1.9% |
| Gain : feed | -10.3% |
| AMEn | -13.5% |
| DM retention | -7.1% |
Due to the low level of energy, it can be generally concluded that, supplementation of nutrients is not sufficient. Thus, feed intake will increase to meet the need. Supplementing a low level energy diets also give no effect to the DM, CP and AMEn retention by either enzyme or acid.
1. Addition of α-galactosidase in experiment I increased the BW and feed intake but not in experiment II.
a. This may due to the amount of citric acid added is higher in experiment I. Weight gain and feed intake was decrease by adding only citric acid but not with both citric acid and α-galactosidase together. The addition of α-galactosidase increased the retention of NDF and reducing sugar concentration.
b. The hydrolysis of α-galactosides took place by enzyme α-galactosidase. However, growth of chicks was not affected by enzyme treatment.
2. There was no effect or negative effect of treatment of citric acid on the growth performance. Retention of DM, CP and NDF was improved in experiment I. in experiment II; addition of 1.5% citric acid reduced the pH of crop content.
3. Both experiment suggested interactive effects of α-galactosidase and citric acid. The weight gain and gain to feed ration in experiment I were depressed due to correction of supplementation by α-galactosidase.
a. Supplementation of both α-galactosidase and citric acid significantly increase the retention of DM, NDF, and AMEn of the diets compared to diets with neither α-galactosidase nor citric acid alone.
b. The supply of both factors caused greater gain to feed ration compared to chicks fed with citric acid alone.
c. AMEn can be improved for broiler chicks by treatment of α-galactosidase in diets which in result, will improve the growth performance.
d. Citric acid inhibits the pathogenic bacteria such as salmonella spp. in poultry diets but may give negative effect to the growth performance. However, addition of α-galactosidase together in the diets will correct the negative effect of citric acid.
4. As the conclusion, the addition or by supplementing both α-galactosidase and citric acid simultaneously will be more beneficial for nutrient retention and growth performance compared to treatment of supplementing on either the enzyme or the acid alone.
1. TME is the True Metabolizable Energy
2. AME is the Apparent Metabolizable Energy
3. Ad libitum is a feeding condition in which the mode is based on favor. The feeding mode is not quantized.
4. Association of Official Analytical Chemicals, 1984 (AOAC), Official methods of analysis, Washington DC.
5. Feed intake is the amount of feedstuff that was taken by chicks and the weight gain is the increase or decrease in their mass at a particular time. Gain: Feed ratio is the relationship between both variables that measures the efficiency of the feeding materials towards the growth performance that is measured by its weight.
