RU2526204C1 - Method of determining energy value of white lupine grain - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: energy value is determined based on the calculation of the activation energies of chemical components as the sum of the activation energies of the grain cover and core of white lupine, multiplied by the mass fraction of the cover and core in the grain, respectively. To calculate the activation energy the data of thermogravimetric and differential-thermal analysis are used, obtained in continuous heating of samples at a rate of 20 deg/min to thermal decomposition of the components of the grain cover and core.

EFFECT: invention enables to estimate fast and accurately the energy value of feed white lupine grains for feeding farm animals.

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Description

The invention relates to agriculture, in particular to fodder production and assessment of the energy value of feed for animals (agricultural and domestic) containing white lupine grain.

The modern system of normalized balanced animal feeding is based on the assessment of the nutritional / digestibility of feeds by calculating the exchange energy (OE) using experimental data from balance experiments or according to the chemical composition of feed from the reference and scientific literature. The exchange energy is calculated according to the chemical composition of the feed, taking into account the content of crude protein, crude fat and carbohydrates in the form of nitrogen-free extractives (BEV) and taking into account their digestibility coefficients and energy value (energy content in joules). However, the reliability of the calculated data on the metabolic energy of the feed depends on the accuracy of the chemical analysis of all nutrient components.

A study of the chemical composition and energy value of white lupine grains using the example of seven varieties of white lupine breeding RGAU-Moscow Agricultural Institute named after K.A. Timiryazev and production crops at the IVMichurin school in the Tambov region was carried out in 2008-2012. on samples obtained within 2-3 adjacent years (Shtele A.L., Tsygutkin A.S., Terekhov V.A. Biological and fodder value of white lupine grain as a source of feed for poultry // Materials of the All-Russian Scientific and Practical Conference T. 1. - Belgorod: Publishing House "Fatherland", 2012. - S. 339-344).

The calculation of the energy value of lupine (Table 1) was carried out by the chemical composition and digestibility coefficients of nutrients according to the formula:

OEkcal / 100g = 4.20 SP × 74% SP ×% S + 9.20 SG × 86% SO ×% SO + 4.13 BEV × 57% BEV ×% BEV

Table 1 Chemical composition (%) and energy value of white lupine (for adjacent crops in 2008-2009) Indicator Start Manovitsky Gamma Delta Degas Deter Desniansky Average Moisture 9.92 10.01 8.86 8.66 8.93 8.92 8.78 9.15 Dry matter 91.08 89,99 91.14 91.34 91.07 91.08 91.22 90.95 OE, kcal 100 g 261 261 269 269 267 268 274 267 OE, MJ / kg 10.93 10.93 11.26 11.26 11.18 11.22 11.47 11.18 Crude protein 33.62 34.25 34.97 33.09 33.37 34.69 31.97 33.71 Crude fat 10.41 9.57 10.70 11.06 10.67 10.35 11.58 10.62 Crude fiber 10.04 9.98 10.01 10.19 10.48 9.58 9.52 9.97 Bev 33.42 33.12 32.07 33.52 33.04 33.18 35.01 33.30 Crude ash 3,59 3.07 3.39 3.48 3,51 3.28 3.14 3.35

Additionally, in 2012, studies were carried out on the chemical composition of three samples of white lupine feed: whole grain, crushed grain (core) and the outer shell (table 2).

table 2 Chemical composition (%) and energy value of fodder products of white lupine grain Indicator Whole grain Broken grain Shell Moisture 12.08 10.57 10.66 Dry matter 87.92 89.43 89.34 Metabolic energy: kcal / 100 g 264 305 252 MJ / kg 11.09 12.80 10.58 Crude protein 35.19 42.06 4.31 Crude fat 9.64 11.03 1.28 Crude fiber 9.40 1.74 37.90 Bev 33.69 34.60 45.85 Crude ash 3.32 3.62 2.09 Calcium 0.30 0.14 0.72 Phosphorus 0.40 0.49 0,03

Studies of the chemical composition of the grain of white lupine were carried out in the Test Center of VNITIP RAAS, calculations of the energy value of the feed were performed in the laboratory of white lupine of the Russian State Autonomous Agricultural University named after K.A. Timiryazev.

A known method for determining the metabolic energy of feed from white lupine, based on the determination of crude protein, crude fat, starch and sugar. Crude protein is determined by Kjeldahl, crude fat in the Soxhlet apparatus. The determination of sugar and starch is based on the extraction of soluble carbohydrates (sugars) from the feed with distilled water at a temperature of 70-80 ° C and the subsequent hydrolysis of starch in concentrated hydrochloric acid. In the calculations of the energy value of feed, fiber is not taken into account (Evaluation of the quality of feed, organs, tissues, eggs and poultry meat: Methodical guide for zootechnical laboratories. VNITIP: Sergiev-Posad. 2009. - 112 pp. Prototype).

The calculation of the exchange energy (OE) in kJ / 100g of feed from lupine grains is calculated by the regression equation:

OE = 4.184 (53 + 38 ×% crude protein + 2.25 ×% crude fat + 1.1 ×% BEV) (1)

The disadvantage of this method of determining the energy value of the grain of white lupine is the duration of the analysis when determining the chemical composition of grain samples, the large energy and labor costs associated with the use of a large number of expensive chemicals.

The objective of the invention is to reduce energy and labor costs for determining the energy value of the grain of white lupine, while improving accuracy.

The problem is achieved in that the energy value is determined on the basis of the calculation of the activation energies of the chemical components as the sum of the activation energies of the shell and kernel of the white lupine grain, multiplied by the mass fraction of the shell and core in the grain, respectively. To calculate the activation energy, we use the data of thermogravimetric and differential thermal analysis obtained by continuously heating the samples at a speed of 20 deg / min until the thermal decomposition of the components of the shell and core of the grain.

Samples of substances have an individual thermal characteristic that reflects its behavior when heated and depends on the composition, properties of its structure, mechanism and kinetics of thermal transformation reactions. After processing the differential thermal analysis curves, a qualitative characteristic of the composition of the samples under study is obtained, and a quantitative characteristic of the composition of the substance is obtained by the area and height of the peaks. The calculation of thermodynamic characteristics is carried out on the basis of the assumption that the reactions relate to decomposition reactions are monomolecular and the kinetic equation is valid for them:

$$-\frac{dC}{dt}=\frac{k_0}{b}\cdot e^{-E/RT}\cdot C,(2)$$

where C is the fraction of substance (A) that takes part in the reaction and remains in some stage of it; k is the reaction rate constant from the equation k = k ₀ · e ^{-E / RT} ; k ₀ is the preexponential factor; n is the reaction order; E is the activation energy, kcal / mol; R - 1.987 cal / mol · deg; T is the absolute temperature in degrees Kelvin, $$b=\frac{dT}{dt}.$$

For subsequent calculations of the thermodynamic characteristics and parameters of the kinetic equation, estimates of the chemical composition of white lupine grain samples, computer software is used.

To determine the chemical composition of the grain of white lupine, the sample is placed in a thermoanalytical complex based on a derivatograph, where the sample is heated in an atmosphere of air at a speed of 20 deg / min, kaolin is used as a standard. Heating is carried out to a temperature of 450 ° C for 20 minutes A separate analysis of the shell of the grain and core of white lupine is carried out taking into account the mass fraction of the shell and core in the grain of lupine.

Example 1 (prototype). Determine the content of crude protein, crude fat, sugar and starch in the kernel of white lupine grain (mass fraction of the core in the grain 0.83) of Degas variety by chemical analysis and calculate the exchange energy according to equation (1). The results of the calculation of the exchange energy are presented in table 3.

Example 2 (prototype). The content of crude protein, crude fat, sugar, and starch is determined in the shell of the grain (mass fraction of the shell in the grain of 0.17) of Degas white lupine by chemical analysis and the exchange energy is calculated according to equation (1). The results of the calculation of the exchange energy are presented in table 3.

Example 3. A sample of the shell of the grain of a white lupine of Degas variety is placed in a thermoanalytical complex and heated at a speed of 20 deg / min to a temperature of 950 ° C. A comparison sample is kaolin. At the same time, the mass loss of the sample during analysis (TG curve), thermal effects (DTA curve) and peak peaks during thermal decomposition (DTG curve) are simultaneously controlled. The mass fraction of each of the components in the sample is calculated according to the mass loss data and peak maximum temperatures, activation energies according to equation (2). Then calculate the energy value of the sample by the equation:

E = m ₁ × E _a1 + m ₂ × E _a2 + ... + m _n × E _an (3),

where E is the energy value of the sample, m _n is the mass fraction of the nth component in the sample, E _an is the activation energy of the nth component.

The results of calculating the energy value are given in table 3. From the results of thermal analysis it follows that the main weight loss of the samples — decomposition of organic components — occurs up to a temperature of 400 ° C. It is also noted that up to a temperature of 150-180 ° C, water is absorbed from samples of hygroscopic or interlinked water. Therefore, in subsequent calculations of energy value, components are accepted that decompose in the range of 180-400 ° C.

Example 4. Similar to example 3. The difference is that as a sample for analysis using the kernel of the grain of a white lupine variety Degas. The results of the calculation of energy values are given in table 3.

Example 5. Similar to example 4. The difference is that the heating is carried out at a speed of 10 deg / min. The results of the calculation of energy values are given in table 3.

Example 6. Similar to example 4. The difference is that the heating is carried out at a speed of 10 deg / min to a temperature of 650 ° C. The results of the calculation of energy values are given in table 3.

Example 7. Similar to example 4. The difference is that the heating is carried out to a temperature of 650 ° C. The results of the calculation of energy values are given in table 3.

Example 8. Similar to example 7. The difference is that the heating is carried out to a temperature of 450 ° C, the heating rate is 20 deg / min. The results of the calculation of energy values are given in table 3.

The energy value of the grain is calculated taking into account the mass fraction of the grain shell and the core of white lupine and the total activation energies calculated according to equation (3) as follows:

E _grains = m _obl × E _obl + m _core × E _core (4).

Table 3 Energy value calculation results (kJ / 100g) Example E _core E _obol E _grain Note one 1045 2 108 1153 By the formula (4) from example 1 and 2 3 110 four 1049 1159 By the formula (4) of example 3 and 4 5 1053 1163 By the formula (4) of example 3 and 5 6 1048 1158 By the formula (4) of example 3 and 6 7 1050 1160 By the formula (4) of example 3 and 7 8 1047 1157 By the formula (4) of example 3 and 8

According to thermal analysis, we can conclude that an increase in the heating temperature of samples over 450 ° C does not lead to a change in the calculated values of energy characteristics, but only increases the experiment time and energy and labor costs. A decrease in the heating rate from 20 deg / min to 10 deg / min also does not lead to a change in the calculated values of the energy characteristics, however, the experimental time doubles.

Using the proposed method will reduce energy and labor costs for determining the energy value of the grain of white lupine, while improving accuracy.

Claims (1)

A method for determining the energy value of white lupine grain based on the calculation of the energies of its chemical components, characterized in that the energy value is determined as the sum of the activation energies of the shell and core of white lupine grain multiplied by their mass fraction in the grain, and the activation energies are calculated according to thermogravimetric and differential thermal analysis obtained by continuous heating of samples at a speed of 20 deg / min to the temperature of thermal decomposition of the organic components of the shell and core grain.