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Extrusion technology in soya seeds processing

Tuesday, 09 June 2015 08:38

Today such product as soya dominates in protein supply of life stock in America and the countries of Europe . And it is explained by 30-40 % protein and up to 20 % fat content in soya seeds. However in raw state soya is not applied in fodder production because of its low digestability, caused by antinutritients with prevailing protein nature. These are protease retarders , hemagglutinents, saponins, lipase ferments, lipooksidasa, etc.

Among soya antinutritients the dominating one is trypsin retarder the concentration of which exceeds 20 mg /g Maximum allowance of trypsin retarder depends on protein content. It is considered that every 10 % of protein should have no more than 1 mg/g of trypsin retarder. Techniques to define trypsin retarder activity are very toilful and long, therefore they are basically used in scientific researches.

In practice to estimate the antinutritients content in soya the indirect parameter is applied. This paramter is an activity of urease ferment which at thermal processing loses it together with the majority of antinutritients. It is established that at urease activity 0,1-0,3 points рН , the basic soya antinutritients are inactivated up to the safe level.

Till now only protein soya fraction obtained after oil extraction have been used in fodder purposes. It is a soya sprat, a soy-bean flour, etc.

Composing fodder receipts intended for an intensive poultry fattening and fattening of pigs with a high level of an exchange energy the problem of using full-fat seeds acquires its urgency.

VSRIFI conducted the researches on conditions of soya seeds processing on domestic extruders

The researches have shown that the greatest productivity and the least specific power inputs have been obtained during soya processing on the domestic extruders.
After processing on extruders E-250 soya acquires a grainy structure. The size of particles (less than 5 mm) characterizes it as the product quite adaptable to streamlined production and which without additional underworking can be used in manufacture of fodders and their components.

Thus, extruders E-250 are possible for application in lines to receive full-fat soya on fodder plants of different productivity.

To draw a final conclusion about the efficiency of extrusive technologies to receive full-fat soya, biological experiments on young pigs (2 week pigs), chickens - broilers and hens - layers were carried out. According to the experiment scheme control and test groups were formed from animals and birds. The control group were fed by the fodder containing soya sprat and sunflower oil. In receipts for the test groups these components were replaced by full-fat extruded soya in different quantities with urease activity 0,05-0,3 unit рН , trypsin retarder 5,79-7,25 mg/g. Preservation, productivity of animals or birds and fodder expenditures were taken into account in the experiments.

Research-and-production experiment on pigs of breed “White large” at the age of 45 days was carried out at the farm "Vishnevsky" in Voronezh region. It is necessary to point out that in the fodder for the test group the fish flour content has been reduced in addition to the mentioned above replacements. To balance fodder on limiting amino acids synthetic lysine and methionine have been loaded with premix. The fodders worked out for the experiments were equally nourishing, with the exception of "a crude protein” the content which has made 17,0 % (control) and 16,5 % (experiment).

Growth rate of pigs in the groups was rather high. So, at the end of the experiment pigs at the age of 100 days had 40,9 and 41,6 kg of the average alive weight. The daily average increase in alive weight for all period of experiment has made 493-502 g/head. Thus the daily average increase in the alive weight of pigs of the test group receiving mixed fodder with full-fat soya was higher on 1,7 % than of pigs of the control group.

Positive results are obtained also in the experiments with chickens - broilers and hens - layers. So comparing chickens of the control and test groups, receiving animal feed with full-fat soya in amount of 15, 20, and 25 %, we can state that the alive weight of chickens of the test groups on the end of experience was equal (1811-1837g) and did not differ from control one(1831g). Essential differences in the increase of chickens of control and test groups were not found. The same concerns forage conversion. The results of a control slaughter did not show any negative changes in internal organs of test chickens.

In experiment on hens the breed cross Hisexs white at the age of 350 days was used . The experiment lasted 90 days. According to the experiment scheme the control group of hens - layers gained traditional fodder of the receipt PK- 1, fodder for test groups included 10 or 15 % of full-fat soya. The experiments have shown that full-fat soya addition to fodder in amount of 15 % did not have any negative influence on egg production and its intensity with hens of the test groups. Alongside with it the increase of egg weight in this group is registered. Daily consumption of fodders by one head for all period of experiment in control and test groups was approximately equal, however fodder expenditures on 10 eggs and 1 kg of egg weight in the second test group were higher than in control one. Quality of eggs practically did not differ.

Basing on conducted researches the norms to load extruded full-fat soya in fodders were worked out: for 2 weeks pigs and young pigs - 10 %; for chickens-broilers - 15-25 %; for hens - layers - 15 %.

Calculation of economic efficiency of full-fat soya use in fodders is presented in table 5. For example, application of full-fat soya in fodders for young pigs results in depreciation of forages on 1 kg of of alive weight increase, from eighteen roubles seven copecks up to fifteen roubles fifty six copecks. It ensures the profit increase at one head at the rate of seventy five roubles twenty five copecks.

To apply soya seeds as source of protein and energy in fodders, the technology of soya processing with application of extruders, allowing to receive full-fat soya is developed.

L.Bojko, the head of fodder and supplements technologies department, cand of tech. sc.,

Trunova L.A., senior scientific employee VNII KP