Evaluation of the nutritional value of Aspergillus niger fermented palm kernel meal in broiler diets
Abstract: Two experiments were designed to test the growth performance, dry matter digestibility (DM) and crude protein of broiler chickens in untreated palm kernel meal (PKC) and fermented palm kernel meal (FPKC). Effects of CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and total energy (GE). In Experiment 1, different levels of rice bran and palm kernel meal were designed and mixed with Aspergillus niger to screen and determine the optimum fermentation substrate. In this test, the fermentation substrate was set to 70% palm kernel meal (PKC) and 30% rice bran (RB) based on the crude protein, neutral detergent fiber and aflatoxin content (43.31 ppb) in the fermentation product. ). The substrate was prepared according to the ratio, the fermentation process was designed, and the fermented palm kernel meal material was obtained to prepare for the test 2. In Trial 2, the test broilers were divided into 4 groups and fed the same protein and energy level diets, including PKC (20%), FPKC (20% and 25%), to determine PKC and FPKC. The effect on growth performance and nutrient digestibility of broilers. The results showed that the average final body weight of the chicks fed the FPKC basal diet test group was lower than the average final body weight of the chicks fed the PKC basal diet control group; the feed-to-meat ratio (FCR) of the 25% FPKC basal diet test group was fed. For the 2.42, the feed-to-meat ratio (FCR) of the control group fed the PKC diet was 1.85; the digestibility and energy metabolism rate of DM, CP, NDF, and ADF in the FPKC basal diet were lower than those in the control diet.
Key words: fermented palm kernel meal (FPKC) Aspergillus niger growth performance digestibility aflatoxin
Introduction
Palm kernel meal (PKC) is a by-product of the extraction of oil from palm fruit. Malaysia is the world's largest palm oil producer, producing approximately 2 million tons of palm kernel meal per year, most of which are used as feed ingredients for beef cattle and dairy cows. If palm kernel meal can be effectively applied to ruminant and non-ruminant feed, it can not only be used to reserve foreign exchange, but also an energy source with high quality and low price. However, palm kernel meal contains a large amount of fiber and mainly linear mannan, which is used to form an appropriate amount of cellulose and a small amount of other polysaccharide components. In monogastric animals, fibrous tissue cannot be digested and excreted with feces. The use of microorganisms, such as Aspergillus niger, to ferment cereals and beans is a potentially important processing method that can effectively increase its nutritional value (Yigzaw et al., 2001). The purpose of this study was to investigate the effects of different levels of rice bran in the palm kernel meal on the nutritional value of the fermentation product, and the diets fed the fermented palm kernel meal to the growth performance and nutrient digestibility of broilers. influences.
Materials and methods
Test 1
Different levels of rice bran and palm kernel meal were mixed and placed in a 500 ml Erlenmeyer flask for fermentation with Aspergillus niger. The fermentation substrate was treated as follows: T1 (PKC 70% + RB 30%), T2 (PKC 80% + RB 20%), T3 (PKC 90% + RB 10%) and T4 (PKC 100%). The substrate was inoculated with Aspergillus niger spore suspension in an amount of 10% of the substrate. After 8 days of fermentation, a sample of the fermentation product was prepared, and the DM, CP, NDF and ADF contents of the sample were analyzed by a standard method (AOAC, 1984). The content of aflatoxin was determined by enzyme-linked immunosorbent assay. Three replicates were set for each treatment in the fermentation test.
Test 2
T1 fermentation treatment is considered to be the most suitable fermentation substrate for use as a feeding trial. The FPKC sample from T1 was obtained by solid fermentation on a tray of 60 cm x 40 cm x 18 cm. Each tray can hold 1.5kg of fermentation substrate for fermentation. Fermentation time and conditions are the same as test 1. Sixty male chicks were tested and fed from 1 day of age to 21 days of age in the early trial period. Starting from 22 days of age, these chicks were housed in relatively independent cages using a completely randomized design trial. The chicks were assigned to four diet treatment groups and were named: diet 1 (basal diet, control), diet 2 (basic diet + 20% PKC), and diet 3 (basic diet + 20% FPKC) and diet 4 groups (basic diet + 25% FPKC). Feed intake, weight gain and feed to meat ratio were measured weekly. At 42 days of age, 6 chickens were drawn from each treatment group for a digestive test. The data were analyzed by ANOVA using SPSS (1999) general linear regression analysis. The Duncan multiple comparison test method was used to analyze and compare the processing methods.
Results and analysis
Test 1
There was no significant difference in the content of neutral detergent fiber in the fermentation products of different substrate treatment groups; however, there was a significant difference in the content of acid detergent fibers between different fermentation treatment groups (p<0.05), and the content of T1 group was the lowest (24.31%). ), the highest content in the T4 group (28.51%). There was no significant change in crude protein content between the different treatment groups; however, all treatment groups increased the crude protein content by 20% after fermentation. According to the test results, the TME (true metabolic energy) value after FPKC fermentation was lowered. The TME value of the T1 group (5.61 MJ/kg) was lower than that of the T4 group (5.98 MJ/kg). The level of aflatoxin in FPKC was lowest in the T1 group (43.31 ppb) and highest in the T4 group (49.5 ppb). According to the level of aflatoxin after fermentation treatment, the substrate of T1 group was used for feeding experiment.
Test 2
The growth performance of the chickens fed the test diet is shown in Table 1 below.
Although, Test 1 showed that the nutrient content of PKC increased after solid fermentation, the growth performance of the diet 3 group and the diet 4 group fed the FPKC diet was worse than that of the control diet group 1 and the experimental group diet. Group 2 (PKC) indicated that the increase in crude protein content of PKC after solid fermentation was not necessarily reflected in the feeding experiment. During solid fermentation, the increase in crude protein content is due to an increase in non-protein nitrogen, possibly due to the growth of fungal mycelium during fermentation. In addition, the presence of aflatoxin in FPKC may have a negative impact on the growth performance of chicks. Jewers (1990) pointed out that the presence of mycotoxins in feed quickly and directly reflects the phenomenon of hunger strike.
Table 2 lists the apparent digestibility and total energy of DM, CP, NDF, and ADF in each test group diet.
It can be seen from the table that the nutrient digestibility of all the FPKC diets was lower than that of the control and unfermented PKC basal diets due to the negative impact of nutrient digestibility due to the addition of FPKC. This observation may be caused by the inhibition of other anti-nutritional factors contained in FPKC. One of the possible factors is chitin, the component of the cell wall of the fungus Aspergillus niger. Many scholars have reported chitin and chitosan pairs. Chicken growth performance has a negative impact. Razdan et al. (1997) demonstrated that diets fed chitin and chitosan had significantly reduced body weight and feed intake. We can conclude that although the cell wall component of PKC can be decomposed by solid fermentation of Aspergillus niger, the anti-nutritional factors contained in FPKC have an adverse effect on the growth performance of broilers, so FPKC cannot be fully utilized by broilers.
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