EP0743826A1

EP0743826A1 - Treatment of corn with expander

Info

Publication number: EP0743826A1
Application number: EP93922670A
Authority: EP
Inventors: Egil Prestlokken; Jon Jorstad
Original assignee: FELLESKJOPET FORUTVIKLING BA
Current assignee: FELLESKJOPET FORUTVIKLING BA
Priority date: 1992-09-30
Filing date: 1993-09-29
Publication date: 1996-11-27
Also published as: WO1994007376A1; NO177032B; CA2145632A1; FI951494A; AU5158493A; NO923799L; FI951494A0; NO923799D0

Abstract

Processing grain is described. Whole or preprocessed grain is fed into an expander where it is pressed past a hydraulically adjustable resistor at a temperature and pressure that are gradually built up towards predetermined levels as the feed is pressed forwards towards a slot in the adjustable resistor. Processed grain, feed, feedstuffs and mixed feeds and the use of an expander for processing grain are also described.

Description

Treatment of corn with expander.

The present invention relates to a method for processing grain.

The invention is especially intended for processing grain so as to increase the proportion of undegraded protein in the grain without having any marked effect on the digestibility of the carbohydrates.

NO Patent Application No. 884302 relates to the conversion of unstriated meat and offal to textured animal protein. This substance has a low hydrolysable collagen content. The amount of gelatine and/or hydrolysable collagen in the meal, or the material from which the meal is produced, is reduced. The protein in the product is, in its entirety, composed of extracted animal protein. During the production process a heated wet mass of animal meal is formed which is subjected to pressure, and the pressure and temperature which surround the mass are reduced once the textured animal protein product has a content of measurable gelatine that is less that 10% of the dry substances in the product. The fat content is less than 10% in the dried product. During the process the pressure is reduced by extruding the mass from an area of relatively high pressure to an area of relatively low pressure, through an extrusion nozzle. An extrusion-facilitating agent and/or a softener are added during the process.

NO Patent Application No. 820396 describes a method for producing animal feed from agricultural products such as sugar beet or sugarcane mass, citrus pulp, or the substance obtained during the fermentation of agricultural products such as distillers' grains from distilleries. These products or substances are dehydrated by means of a pressing operation and/or an evaporation process. During the process the product or substance is heated in water vapour at a pressure of 0.1-0.8 mpa and at a temperature within the range of 100-210°C. The product or substance is then comminuted in a carrier vapour in that it is crushed mechanically and/or subjected to a sudden fall in pressure which leads to an expansion and bursting of solid particles. An even particle size of 0.5 and 5 mm is thereby achieved. The particles are dried in a heat exchanger where the carrier vapour serves chiefly as a contributory drying agent. The substance is then separated from the carrier vapour and is cooled in a known way per se.

^•?

NO Patent Application No. 753,896 describes a method for producing an enhanced feed for fish and shellfish. This fish and shellfish feed is produced on the basis of proteinaceous fish and meat substances mixed with starch-containing substances. The mixture is thereafter extruded, at a temperature within the range of 90-120°C for a

10 period of time lasting a maximum of 1-3 minutes and at a pressure of a maximum of 1.5 atm.

Patent Application No. 461769 describes a method for producing palatable and non- toxic i5 feedstuffs for ruminants. Starch-containing substances from grain or similar are mixed with nitrogenous substances. The mixture is then processed in an extruder where the substance is heated to a temperature of 120-175°C and in addition is subjected to a pressure of from approx. 28 kg per cπr to approx. 35 kg per cm . The finished

20 product gives rise to increased protein synthesis in the rumen and a protein assimilation effect that is considerably greater than can be achieved by using ordinary mechanical mixtures of the nitrogenous substance and the starch-containing substance.

Patent Application No. 802316 relates to a method for producing a dry ready-to-eat grain

25 product of high fibre content. It is produced by mixing grain dough ingredients with maize bran meal until the product has a fibre content of at least 1.5%. The ingredients are boiled in a boiler/extruder under conditions of temperature and pressure sufficient to cause the dough to expand on the disconnection of the boiler/extruder. The expanded

50 dough structurate is then cut into separate pieces, whereupon it is dried until it has a moisture level of approx. 2-3%.

The present invention thus relates to a method for processing grain, characterized in that

55 whole or preprocessed grain is fed into an expander where it is pressed past a hydraulically adjustable resistor in that the pressure and the temperature are gradually increased to predetermined leveis as the feed is pressed forwards towards a slot in the adjustable resistor.

Both whole and preprocessed grain can be processed according to the present invention. The term preprocessed grain is used to mean, for example, grain that has been rolled, coarsely ground, granulated or subjected to other methods that result in crushed grain. It can be processed separately or mixed in with the rest of the finished concentrate mixture. The mass is fed thereafter into a conditioning zone where steam is added and is mixed into the mass. The mass in then fed into an expander where it is processed at a temperature in the range of 80-190°C, preferably 110-160°C, and most preferably 130-135°C, and under a pressure in the range of 10-150 bar, preferably 30-40 bar.

The processed grain, feed, feedstuff and mixed feed also constitute a part of the invention.

The use of an expander for processing grain is also described. Various studies and experiments are described below. Reference is therefore made to the attached figures where:

Fig. 1 is a schematic illustration of the degradation of protein over time measured in sacco.

Fig. 2 shows the reduction in protein degradation as the rate of passage increases.

Fig. 3 shows how pressure and temperature gradually build up during expansion.

Figs. 4-6 show the effect of pressure and temperature on the degradability of protein and dry matter in preliminary studies.

Fig. 7 illustrates the consequences of expander processing for the raw material costs. Fig. 8 shows the difference between the raw material costs involved in expansion and those involved in non-expansion.

The Norwegian Government has introduced AAT (content of amino acids absorbed in the intestine) and PBV (protein balance in rumen) as measure for protein value in feeds for ruminants. This results in a more goal-oriented utilization of feed protein for inter alia dairy cattle. A balanced supply of AAT and PBV in relation to requirements is central in this context. In the feedstuff table of 11 March 1992, the AAT content and PBV content of barley of normal quality have been put at 102 grams and -48 grams, respectively, per kilo of dry matter, and for oats at 67 grams and 1 gram, respectively, per kilo of dry matter. The degradability of feed protein in the rumen (NGP) and the intestinal digestibility of undegraded feed protein (FINP) for barley are set at 70% and 75 % respectively, and for oats at 88 % and 62% respectively.

Calculations have shown, however, that it will often be desirable to have higher AAT values and lower PBV values than found in grain of normal quality. A higher AAT value in the grain will allow for the inclusion of more grain in the concentrate mixtures. At the same time the cost of the mixtures can be reduced somewhat. The amount of unprocessed oats used in cattle feed can, for example, be reduced by as much as 20% in comparison to today's level. Grain with a low PBV value will, in combination with protein-rich roughage, give the basis for a good total utilization of the protein in the ration.

A higher AAT value and a lower PBV value can be obtained either by increasing the proportion of digestible carbohydrates or by increasing the proportion of undegraded feed protein. An increased proportion of digestible carbohydrates by the gelatinisation of starch is possible. Gelatinised starch will, however, give rise to consequences detrimental to the state and function of the rumen in cattle in high lactation. Gelatinisation is, moreover, an expensive solution in terms of the techniques used and the work required. In sacco is the best method we have today for examining the degradability of food in the rumen. This method is based on a standard procedure (Vik-Mo 1988). The principle of the method is to determine how great a proportion of the feed disappears from nylon bags that remain in the rumen for different periods of time.

The degradability of protein in the rumen is central in the evaluation of protein for ruminants.

Generally the degradation of protein can be described on the basis of Fig. 1 (SATTER, 1986).

Easily soluble protein (NPN = non protein nitrogen) which constitutes the greatest part of fraction A in Fig. 1, will be converted quickly by the microbes in the rumen, and ammonia will be formed. A high content of NPN therefore also usually gives rise to a high level of degradability. The conversion of the pure protein that is degradable (fraction B) takes place in several stages. First bacterioenzymes cause the extracellular breakdown of the protein into peptides/amino acids. Most of these peptides/amino acids are then absorbed by microbes and broken down further to ammonia, inter alia. A proportion of the peptides/amino acids will be incorporated directly into the microbe body, or will pass out of the rumen unaffected and thereby be a source of bypass protein. The degradability of fraction B is determined by several factors, but in principle the degradability is determined by how quickly the degradation occurs (c= rate of degradation, %/hour) and how long the feed remains in the rumen (k = rate of passage, %/hour). Both these factors are taken into account, in addition to the size of fraction A and fraction B, when calculating the total degradability. The protein that is not broken down in the rumen or is broken down very slowly constitutes fraction D.

In practice, the degradability is calculated on the basis of two equations given by

0RSKOV & McDONALD (1979). The necessary information with regard to fraction A and fraction B can be found by means of the in sacco method. A special programme in the Statistical Analysing System (SAS) calculates A, B and c from equation 1. The solutions to A, B and c are later inserted in equation 2 which gives us the effective protein degradation (EPD) in the feed.

Equation 1 p = A + B(l -(e^"ct)) Equation 2 EPD = A + (B*c / c+k) where: p = substance washed out over time t

A = substance which is degraded immediately

B = substance which can be degraded over a length of time c = the degradability rate of fraction B, %/hour k = rate of passage of feed through the rumen, %/hour

(according to the AAT-system, 8% /hour is standard.

The quantities that are described in connection with Figure 1 will vary especially between feedstuffs but also within the same feedstuff. This in turn will have a great effect on the protein value in the feed. The value of the effective protein degradation is thus a total picture of what really happens in the rumen. Today, it is this method that tells us most about how the protein in a feedstuff reacts in the rumen and what protein value the feedstuff has when given to ruminants.

The effective protein degradation will depend upon the rate at which the feed passes through the rumen. Figure 2 shows how the degradability is reduced when the rate of passage is increased for control in products 2, 3 and 4.

The rate of passage will vary according to a number of conditions, inter alia the feed and the feeding conditions. This in turn may be of consequence for how the protein reaches the intestine. A high feed intake and a high proportion of concentrate will increase the rate of passage, whilst low digestibility will reduce it.

The degradation rate may be related to a number of significant sources of error. Firstly, the degradation rate in a feed mixture will be an average value for several feedstuffs. A second important point is that not all the protein which leaves the nylon bag need necessarily be degradable in the rumen.

An expander is used during the processing of the grain. There are several kinds of expanders on the market today. Highest pressure and temperature are reached with the expander produced by A. Kahl Nachf, Hamburg, Germany. It is this expander that has been used in the experiments and studies.

The expander is in principle constructed like a simple extruder, and the feed is pressed past a hydraulically adjustable resistor. The hydraulically adjustable resistor allows for a relatively good control of the actual steps involved in the processing. By adjusting the resistor the pressure can be made to rise to 80-100 bar. At the same time the temperature in the feed can rise to 150-190°C. However, for practical reasons it will seldom be relevant to use processing conditions over 100 bar and 190°C. The expansion is a mechanical process in which the desired effect is achieved by means of pressure and friction.

Pressure and temperature are gradually increased as the feed is pressed forwards towards a slot in the adjustable resistor. The close relation between pressure and temperature is outlined schematically in Figure 3. The figure also shows that the intense processing lasts for a very short period of time. After passing the resistor the pressure falls instantly. At the same time there is a a certain degree of expansion in the feed. The fall in pressure also leads to the evaporation of moisture and a rapid fall in temperature in the feed.

The expander kills the germination capacity of the grain and has an effect on the degradability of the protein and dry matter in feed for ruminants. This is of great practical, competitive and financial consequence for the production and use of concentrates.

The expander can be used inter alia for the production of feed for ruminants, poultry, pigs and fish. An expander placed in the production line prior to the pellet press will produce better pellets and increase the capacity of the pellet press considerably (approx. 20-40%). Energy consumption during pelleting will normally decrease somewhat. The heat treatment will kill a number of bacteria such as, for example, Salmonella, and thus improve the hygienic quality of the feed. Reduction in the activity of the natural inhibitors in the feed, such as glucosinolates, will probably also take place. The expander also makes it possible to increase the mixing in of liquid feedstuffs such as fat and molasses as they can be added directly in the expander.

A large number of studies and experiments have been carried out. The first studies were meant to show whether there were grounds for assuming that there is any real effect of pressure and temperature on the degradation of protein and dry matter in the rumen.

The samples were tested for the degradability of protein and dry matter, and each sample was tested in two cows. Table 1 discloses data relating to the samples and the results for effective protein degradation (EPD) and effective degradation of dry matter (EDD) in the rumen.

Table 1: Values for effective protein degradation (EPD) and effective dry matter degradation of (EDD) in the rumen

The values for EPD and EDD are an average for two cows. In general, there was little variation between cows.

The results after the processing are, as expected, not as marked for feed A for dairy cows (product 4) as for products 2 and 3. This is because feed A for dairy cows is composed of several feedstuffs. Nevertheless, it can be seen that the highest pressure and temperature have given rise to the lowest protein degradation. Figures 4-6 give the results from Table 1 in the form of bar diagrams.

In sacco experiments

These experiments were carried out in order to determine the effect of the expander on protein degradability (NGP) and the degradability of dry matter (NGT). The following six raw materials were selected: ground barley, rolled barley, ground oats, rolled oats, extracted soybean meal and extracted rapeseed meal. In addition, four simple concentrate mixtures were made of these raw materials (mixed feed 1), with ground and rolled grain of both low protein content (17% crude protein) and high protein content (35 % crude protein).

A total of ten samples were processed in the expander at three different levels of pressure and temperature as shown in Table 2.

A sample was taken at each processing level to be used in the in sacco determination of the NGP and the NGT.

A total of 35 samples were tested using the in sacco method. Three cows per sample were used as parallels for the individual raw materials and the mixed feeds 2, whilst two cow were used for mixed feeds 1.

The results were as follows:

Temperature and pressure

Table 2 shows an overview of the temperature and pressure reached at the different levels of processing which have been compared.

Table 2: An overview of temperature and pressure at different levels of treatment for the different products

Process ... Mild Medium Intense

Temp. Press. Temp. Press. Temp. Press. °C bar °C bar °C bar

The temperature and pressure were measured during the passage of the feed through the adjustable resistor in the expander. During mild processing an attempt was made to keep the temperature at approx. 130°C. It can be seen that this temperature was reached at different pressures. A temperature of 155°C was desirable during the medium level of processing. With soybean meal, however, the pressure had to be increased.

During intense processing, no limits were made on the production process. The aim here was primarily the highest temperature possible within the capacity of the equipment. For most of the feedstuffs, a limit was reached between 160 and 180°C and at a pressure of 100 bar. When processing rolled oats, the temperature did not rise beyond 145°C, even at high pressure. In the case of rapeseed meal, the temperature reached 190°C.

Degradability of protein (NGP') Table 3 shows a total overview of protein degradability (NGP) in the in sacco experiment. Table 3: Degradability of protein (NGP), rate of passage 8% /hour

Protein de ra ti

Process ... Feedstuffs: Ground barley Rolled barley Ground oats Rolled oats Soybean meal Rapeseed meal Mixtures (1): Low prot. , rid. Low prot. , grd. High prot., rid. High prot., grd. Mixtures (2): High prot., grd. Low prot. , grd.

1) Mixtures which have been processed as a mixture in an expander.

2) Mixtures containing feedstuffs that have been processed separately in an expander and later mixed manually to form a mixture.

It can be seen from this table that the protein degradability is reduced for all feedstuffs that have been processed in an expander. This applies especially to the grain products (barley and oats) and the mixtures with a low protein content (a lot of barley and oats). In these products the NGP is reduced by 15-20 % -units. The reduction for ground oats is a total of 33.5 %-units. There is also a substantial reduction (10-15 %-units) in the case of soybean meal and the protein-rich mixture containing rolled grain. The reduction in degradability is smaller for rapeseed meal and the protein-rich mixture containing ground grain.

It can be seen from Table 3 that in general there has been little to be gained in terms of reduced degradability by raising the temperature above 130°C and the pressure over 40 bar. During the intense processing there was, in several cases, a tendency towards a neutralizing effect. However, oats, and to some extent rapeseed meal, are the exception.

Experiments with processed barley

Table 4 shows the in sacco degradability of protein in the rumen, and the digestibility of dry matter, protein and undegraded protein in the intestine measured by using mobile nylon bags in unprocessed and FK-processed barley (the term FK processing is used to mean the expansion of feed in a Kahl expander). The content of AAT and PBV are calculated on the basis of 41 % digestibility of fibre and 92 % digestibility of nitrogen-free extracts (NFE). All studies and calculations have been carried out in accordance with Nordic guidelines in the AAT/PBV system in the Department of Animal Science (IHF) at the Norwegian Agricultural University. The conditions during processing are approx. 130°C and 30 bar for all processed samples in Table 4.

Table 4:

Intestinal digestibility of dry matter, protein and undegraded protein (FINP) measured by means of a mobile nylon bag, in sacco degradability of protein in the rumen (NGP), and the content of amino acids absorbed in the intestine (AAT) and the protein balance in the rumen (PBV) in unprocessed and FK-processed barley. Measurements (N), mean and variation. ΔProc. is the change brought about by FK processing as compared with unprocessed barley. Processing conditions are approx. 130°C and 30 bar pressure. ιt

The protein values in unprocessed barley in Table 4 are very similar to the values in the new feedstuff table. The FK processing of barley has reduced the NGP by 18 % -units from 68% in unprocessed barley to 50% in processed barley. The total digestibility of dry matter and protein measured by using a mobile nylon bag is virtually unaffected by the processing. The estimated digestibility of the undegraded protein (FINP) has been increased by 7 % -units, from 79% in unprocessed barley to 86% in processed barley. The AAT value in barley is increased by 18 grams per kilo of dry matter from 104 in unprocessed barley to 122 in processed barley. At the same time the PBV value has been reduced from -43 grams per kilo of dry matter in unprocessed barley to -66 grams per kilo of dry matter in processed barley.

When calculating the AAT and PBV, it is assumed that the processing does not have any particular effect on the content of digestible carbohydrates. Results from digestibility tests on sheep fed with processed concentrate mixtures give no indication of an increase in the digestibility of carbohydrates due to the processing.

The experiments show a clear effect on the NGP and the estimated protein value when barley is processed at about 130°C and 30 bar. The processing conditions at 125-130°C and 30 bar seem to be a lower critical limit for obtaining the AAT and PBV values in barley as given here. Gentler processing by means of an expander, and even normal pelleting, gives some reduction in NGP, but the effect is nonetheless small in comparison with the aforementioned FK processing at 130°C. There seems to be little to be gained from processing at temperatures above 130°C in terms of a further increase in the protein value.

Pelleting FK-processed barley does not cause a further reduction in the NGP. The effect on the NGP is therefore due to pressure and temperature treatment given in the expander and not the pelleting. Results of the expander experiments

Table 5 shows the effect of processing on the NGP and AAT values in barley and oats, and also the NGP in mixtures. Six portions of barley and five portions of oats were tested. The in sacco degradation of protein and dry matter has been determined for all portions, whilst the AAT value has been calculated for five portions of barley and two of oats. In the case of mixtures, the variation in protein content makes it difficult to compare the AAT value. The NGP in six mixtures with a large quantity of barley and oats has nevertheless been included.

Table 5: The effect of expander processing on the degradability of protein in the rumen (NGP) and content of amino acids absorbed in the intestine (AAT). Arithmetic mean and range of variation.

The expander tests show the following:

Based on the average of six portions, the NGP is reduced by 20 % -units in barley that has been expanded.

Based on the average of five portions, the AAT is increased by 19 grams per kilo in barley.

Based on the average of five portions, the NGP is reduced by 21 % -units in oats that have been expanded.

Based on the average of two portions, the AAT is increased by 22 grams per kilo in oats.

Based on the average of six portions, the NGP is reduced on expansion by 10 %- units in mixtures. When there is 15 % protein in the mixture, this constitutes approx. 11 grams AAT per kilo.

Steaming barley causes a great reduction both in NGP and DDG

The digestibility of raw materials and mixtures is described below.

Digestibility tests with sheep, mixtures (ED

Table 6 discloses the digestibility of dry matter, protein, nitrogen-free extracts (NFE), fibre and fat in unprocessed and expanded concentrates.

Table 6:

Digestibility of dry matter, protein, nitrogen-free extracts

(NFE), fibre and fat in unprocessed and expanded concentrates

NFE Fibres Fat

oo

84,6 53,0 99,7 84,6 28,7 96,3

84,3 50,0 98,0 85,3 35,1 95,4

The digestibility tests show the following:

Expansion does not have a systematic effect on the digestibility of dry matter and protein.

Expansion causes a small tendency towards increased digestibility of NFE.

The digestibility of fibres and fat is reduced by approx. 15 % -units and approx. 3 %-units, respectively, by expansion.

Table 7 shows the digestibility of dry matter, protein, nitrogen-free extracts (NFE), fibre and fat in a mixture containing Soy-Pass and a mixture containing expanded barley and oats.

Table 7: The digestibility of dry matter, protein, nitrogen-free extracts (NFE), fibre and fat in a mixture containing Soy-Pass and a mixture containing expanded barley and oats.

These digestibility tests show the following:

A tendency towards greater digestibility of dry matter, protein and in particular fibre in a concentrate mixture containing barley and oats in comparison with a mixture containing Soy-Pass.

No difference in the digestibility of NFE.

A tendency towards lower digestibility of fat in the expanded mixture.

Intestinal digestibility of barley, oats and mixtures (El)

Table 8 shows the intestinal digestibility of dry matter, protein and undegraded protein (UDP) measured by using a mobile nylon bag, and the in sacco degradability of protein (NGP) for barley, oats and mixtures. Table 8:

Intestinal digestibility of dry matter and undegraded protein (FINP) measured by using a mobile nylon bag, and the in sacco degradability of protein in the rumen (NGP) in unprocessed and expanded barley, oats and mixtures. Measurements (N), mean and variation. Δ Exp. is the change after expansion as compared with unprocessed grain and mixtures.

Unprocessed Expanded

N Mean,# Variation Δ Exp.

t

The intestinal digestibility tests show the following:

The degradability of protein in barley, oats and mixtures is on average reduced by 15, 22 and 11 % -units respectively by expansion.

The digestibility of dry matter measured by means of a mobile nylon bag shows, at the same time, a tendency towards an increase of 1, 3 and 3 % -units respectively on expansion.

The digestibility of total protein measured by means of a mobile nylon bag shows no or only a slight tendency to increase on expansion.

Due to a reduction in the degradability in the rumen and small or no change in the total digestibility of protein, the digestibility of undegraded protein increases substantially in all kinds of feedstuffs. The increase is especially great for oats.

The increase in digestibility of INP in barley, oats and mixtures is 9, 27 and 6 %- units, respectively.

Expansion versus steam boiling

In Table 9 a comparison is made between barley that has been expanded and barley that has been steam boiled (the SLR method) to examine the effect on the in sacco degradability of protein in the rumen and the intestinal digestibility of dry matter, total protein and undegraded protein measured by means of a mobile nylon bag. Table 9:

Intestinal digestibility of dry matter, protein and undegraded protein (FINP) measured by using mobile nylon bags, and the in sacco degradability of protein in the rumen (NGP) in expanded and steam-boiled barley. Measurements (N), mean and variation. Δ Steam is the change brought about by steam boiling as compared with expansion.

t

The results show the following:

Steam boiling reduces the NGP in comparison with expansion.

There is no difference between the two processing methods in terms of the digestibility of dry matter.

There is a tendency towards a reduction in the digestibility of protein on steam boiling (ie, the proportion of indigestible protein increases).

Due to the low NGP in steam-boiled barley, steam boilng has virtually no effect on the digestibility of the INP, although the proportion of indigestible protein has increased a little.

The values of the NGP and the total digestible protein in steam-boiled barley are the lowest that have been measured for barley hitherto.

Degradability in raw materials versus degradability in a mixture of raw materials

In order to see the relation between the degradability of protein in raw materials versus the degradability in a mixture of raw materials, one must take into account how great a proportion of the protein in the mixture originates from the individual raw material and multiply this by the relevant NGP. If protein from barley constitutes 50% of the protein in a mixture, a reduction of, for example, the NGP in the barley of 20 % -units will reduce the NGP in the mixture by 10 % -units.

In Table 10 the NGP in a processed and unprocessed mixture, with a high and low protein content respectively, is calculated. Furthermore, the calculated values are compared with values found in in sacco tests. Table 10

Degradability of protein (NGP) in mixtures calculated on the basis of the PDG in the raw materials and measured NGP in mixtures.

Calculated Measured ( 1 ) Measured (2)

Protein levfel Low High Low High Low High

NJ Ul

Unprocessed 73_#2 64.0 68.6 61.3 66,3 59. Processed 52,2 54,3 48.9 57.6 47.4 50.0

1)

Measured in real mixtures, ie, mixtures produced in ordinary production facilities.

2)

Measured in mixtures that have been made by mixing manually the unprocessed and processed raw materials.

This shows that the degradability of protein in the mixture, calculated on the basis of the NGP in the raw materials, is on average 3 to 5 % -units higher than measured values for NGP.

The consequences of expanding concentrates for cattle

The potential for saving on the costs of raw materials by expanding concentrates for cattle under these conditions is between NOK 50 million and NOK 100 million per annum based on today's prices, depending upon the availablity and need for alternative protein-rich raw materials. This is equivalent to 4-8% of the total costs for raw materials in production mixtures for dairy cattle.

Mixed feed for dairy cattle in the AAT systems

The introduction of the AAT system will give rise to new concentrates for cattle. Hitherto, it has been anticipated that it will be necessary to have four to five mixed feeds for dairy cattle in the AAT system.

Coarsely ground grain mixtures Production mixtures

* 90 grams AAT per feed unit milk (FEm), low PBV value ("Cowfeed" low PBV)

* 90 grams AAT per FEm, high PBV value ("Cowfeed", high PBV).

* 95-105 grams AAT per FEm, high AAT value ("Cowfeed", high milkers).

AAT concentrates

The need for AAT in milk production is approx. 90 grams AAT per FEm (85 grams AAT per kilo at 94 FEm per 100 kg) when the cow is fed with energy according to the norm. It is therefore natural that in the production of mixed feeds for dairy cattle one aims to meet this need "Covfeed", low PBV and "Cowfeed", high PBV). Varying PBV values in the concentrates will make it possible to utilize the protein in the total ration in the best way possible. In cases of high yield and low energy relative to the norm, the need for AAT per FEm increases. Ideally this must be topped up with a protein concentrate. In everyday feeding there are relatively strong desires to be able to use just one concentrate mixture. This mixture should cater as much as possible to the high yield cows in the herd. What AAT level this mixture should have is difficult to determine now, but from 95 to 105 grams AAT per FEm covers the range of variation.

It is difficult to say how great the quantities of feed for dairy cattle within the relevant AAT levels will be. The total sales of feed for dairy cattle in 1990 amounted to approx. 580,000 tonnes. If it is assumed that the mixture with 90 grams AAT per FEm covers the volume of feed A for dairy cattle and 10%-feed for dairy cattle, and the mixture containing 95-105 grams AAT per FEm covers the volume for 15 %-feed for dairy cattle, we will get the following figures for estimated quantity:

Production mixture 90 grams AAT per FEm : approx. 406,000 tonnes Production mixture 95-105 grams AAT per FEm: " 116,000 tonnes

Today, coarse grain for ruminants and 10%-feed for dairy cattle contain too little AAT per FEm for them to be recommended alone for dairy cattle. Similarly, the AAT content in feed A will normally be on the low side. The 15 %-feed for dairy cattle will normally provide a high enough AAT supply, but at the same time the high crude protein content will give a high PBV value and a relatively high price.

When introducing the AAT system, it is of great importance to find ways of increasing the AAT content in concentrates. In this context, expansion would seem to be of great interest. Examples of optimization

The additional costs involved in expansion processing are set at NOK 4 per 100 kilos for barley and oats. Otherwise the price of raw materials is as given in today's price list. Table 11 shows examples of optimization of concentrate mixtures with and without expanded barley and oats. It is assumed that the expansion process increases the AAT content from 90 to 110 grams AAT per kilo of barley. For oats, it is assumed that AAT is raised from 63 to 82 grams per kilo by the processing. Apart from the expansion and subsequent increase in the AAT value in barley and oats, the conditions in the calculations are equal. The optimizations have been made in format.

By using expanded barley and oats, the crude protein content in the concentrate mixtures can be reduced considerably, without any reduction of the AAT value (Table 11). The PBV content is simultaneously reduced substantially through the reduction of the crude protein content. When using expanded barley and oats, there is no need for herring meal or soybean meal in the mixture at 85 and 90 grams AAT per kilo. At 100 grams per kilo, 3 % herring meal is included. Without a supply of expanded barley and oats, there will however be a need for 3 % herring meal at 85 grams AAT per kilo. At 90 and 100 grams AAT per kilo there will also be a need for 6.6% and 17.7% soybean meal, respectively. At the same time it can be seen from the table that the grain content, as the total of barley, oats and bran, increases on the use of expanded barley and oats.

Negative PBV values of -30 to -40 grams per kilo of concentrate are large. If one is to recommend expanded concentrate with such low PBV values, one must be certain that the crude protein content in the roughage ration is sufficiently high. If the roughage contains too little protein, it is clear at the same time that there are cheaper ways of increasing the PBV in the ration than using herring meal and soybean meal. The use of urea may be one alternative. The addition of fish silage to the concentrate may be another alternative.

By using expansion, the cost of raw materials can be reduced by NOK 15.8 per 100 kilos, at 85 grams AAT per kilo (Table 11). At 90 grams AAT per kilo, the corresponding figures are NOK 25.2 and NOK 35.6, respectively, per 100 kilos of concentrate. The significance of expansion processing is thus greatest at a high level of AAT.

Table 11

The financial consequences of using expanded barley and oats in concentrate mixtures for dairy cattle. Content of crude protein, digestible crude protein, amino acids absorbed in the intestine (AAI) and protein balance in the rumen (PBR).

AAI level 85 α AAI/kg 90 g AAI /kg 100 Process Non-exp. Exp; a I /kg

Non-exp. Exp. Non-exp. Exp.

Feed value:

FUm per 100 kg 94 94 94 94 94 94 Crude prot. g/kg 126.4 105.6 147-.7 104.4 186.5 124-5 Dig. crude prot. g/kgl00„5 81.5 120,3 80.2 156.4 98-7 AAI, g/kg 85,0 85.0 90,0 90.0 100, 0 100.0

PBR, g/kg 9.5 -28,2 7,1 -35,7 36.0 -27,3 o

Raw mat. costs NOK/ 100 kg 262,0 248.2 Difference, NOK/lOOkg 15,8

Expansion versus special quality protein-rich raw materials

Figure 7 shows the significance of expansion in comparison with an alternative method for raising the AAT level in concentrate mixtures. The alternative method is the use of special quality herring meal (compressed meal cake) and special quality soybean meal (Soy-Pass). In the calculations the price of compressed cake is set at a price equivalent to that of low temperature (LT) herring meal. We have added NOK 25 per 100 kilos to the price of Soy-Pass in relation to ordinary extracted soybean meal.

The use of special quality raw materials reduces the costs of raw materials with an increasing AAT level relative to ordinary raw materials. The lowest raw material price is still found when using expanded raw materials, but the differences in favour of the expander are now considerably reduced. With AAT values above 9.5% AAT per kilo, the combination of expansion and special quality protein-rich feedstuffs give the lowest raw material costs.

The financial consequences of expansion

Figure 8 shows the difference in raw material costs in Norwegian kroner per 100 kilos between expansion and non-expansion with an increasing AAT level. The major mixed feed for dairy cattle is expected, as mentioned, to be around 90 grams AAT per FEm (8.5% AAT per kilo in Fig. 7). The reduction in the raw material costs is then NOK 9 and NOK 16 per 100 kilos of concentrate respectively, with the lowest figure when special quality proteinaceous raw materials are supplied. With a total volume of 406,000 tonnes, the potential saving in raw material costs is NOK 35 million and NOK 65 million respectively (3-6% of the raw material costs).

Corresponding calculations for 100 grams AAT per FEm with a volume of 116,000 tonnes gives a potential saving of raw material costs of NOK 15 million and NOK 35 million (6-12% of the raw material costs). This shows that the potential saving in raw material costs by expanding concentrates for cattle under these conditions is between NOK 50 million and NOK 100 million per annum, operating with today's prices, depending upon the availablity of and need for alternative protein-rich raw materials. This is the equivalent of 4-8% of the total raw material costs in production mixtures for dairy cattle.

Claims

P a t e n t C l a i m s:

1.

A method for processing grain, characterized in that whole or preprocessed grain is fed into an expander where it is pressed past a hydraulically adjustable resistor at a temperature and pressure that are gradually built up towards predetermined values as the feed is pressed forwards towards a slot in the adjustable resistor.

2.

A method according to Claim 1, characterized in that feed, feedstuffs or mixtures of feedstuffs and whole or preprocessed grain are processed.

3.

A method according to Claim 1, characterized in that the method is carried out at a pressure of 10-150 bar.

4.

A method according to Claim 1, characterized in that the method is carried out at a temperature of 80-190°C.

5.

A method according to Claim 1 , characterized in that the type of expander used provides the desired effect on the protein.

Processed grain, characterized in that it is produced by the method according to Claims 1 to 5.

7.

Processed feed, characterized in that it is produced by the method according to Claims

1 to 5.

8.

Processed feedstuff, characterized in that it is produced by the method according to Claims 1 to 5.

9.

Processed mixed feed, characterized in that it is produced by the method according to

Claims 1 to 5.

10.

The use of an expander for processing grain.

AMENDED CLAIMS

[received by the International Bureau on 23 February 1994 (23.02.94) original claims 1-10 replaced by amended claims 1-8 ( 2 pages)]

P a t e n t C l a i m s

1.

A method for processing grain for protection of protein against degradation in the rumen, c h a r a c t e r i z e d i n that whole or preprocessed grain is fed into an expander where the temperature and pressure are gradually built up when the grain is mechanically pressed forwards towards an adjustable resistor in the outlet of the expander, wherein

A. the temperature measured on the passage of the grain past the adjustable resistor shall he between 80 and 190°C and preferably between 100 and 150°C,

B. the pressure against the adjustable resistor shall be between 10 and 100 bar, and preferably between 20 and 60 bar.

2.

A method according to Claim 1, c h a r a c t e r i z e d I n that feed, feedstuffs or mixtures of feedstuffs and whole or preprocessed grain are processed.

3.

A method according to Claim 1 or 2, c h a r a c t e r i z e d i n that an expander is used which provides a hasls for the processing of grain according to the above mentioned Claims 1 and 2.

4. Processed grain, c h a r a c t e r i z e d i n that it is produced by the method according to Claims 1 to 3.

5.

Processed feed, c h a r a c t e r i z e d i n that it is produced by the method according to Claims 1 to 3.

6.

Processed feedstuff, c h a r a c t e r i z e d i n that it is produced hy the method according to Claims 1 to 3.

7. Processed mixed feed, c h a r a c t e r i z e d i n that it is produced by the method according to Claims 1 to 3.

8.

The use of an expander for processing grain.