What methods are there for identifying feed quality? A full analysis of practical techniques
Measures for identifying feed quality
1 Comprehensively applying sensory methods to identify feed quality
1.1 Using eyesight to identify the quality of feed
The main thing is to observe the feed's variety, form and colour. When testing, take a handful of the sample and place it on the palm of the hand or on white paper, spread it flat gently with the hand, focus the line of sight on a certain part of the sample, and identify it carefully, checking the uniformity, form, colour and lustre of the grains. For grain raw materials with husks, one can also observe the thickness of the husk, the condition of insect damage, the degree of plumpness and the amount of incomplete grains, etc. For certain varieties, one can even estimate the moisture content, for example with corn, one can observe its colour and the form of the germ; if the colour is bright, the germ is shrunken and hairless, and the grains are uniform with few broken grains, its moisture is generally below 15%; if the colour is dull and lustreless, the germ is not shrunken and is hairy, then its moisture may be above 16%. One can also judge from the colour whether the feed is new or old and whether it has been attacked by mould, for example good-quality feed has a fresh colour and good lustre; feed that has undergone high temperature or been stored for a long time has a dull colour and loses its lustre, and some is accompanied by caking; corn with gibberella disease is pink; the reproduction of penicillium and aspergillus can turn rice yellow.
1.2 Using the hand to feel the feed and judge its quality
That is, take the sample and put it in the palm of the hand, touch it with the fingers, and use the feeling on the surface of the hand to identify whether the grains are smooth or rough, then rub and press with the fingers to identify whether they are soft, hard, plump or shrivelled, or judge the moisture according to the temperature and specific gravity of the grains in the palm. For corn, one can also insert a fingernail into the germ; if it feels loose and soft then the moisture is relatively high, otherwise the moisture is below 14%. When identifying, one can also insert the hand into the feed; if it goes in easily and lightly, and the sound is smooth and bright, then the water content is low; if it is sluggish and difficult to insert, then the water content is high. For powdered feed, one can also grip the sample tightly with the hand; if it feels fluffy and rough, and scatters easily when released, then the moisture is relatively low. When touching feed with the hand, note that the fingers and palm should be clean, there must be no hand sweat, and the method of touch should be chosen according to the grain shape and characteristics of the feed.
1.3 Identifying feed quality through the sense of smell
Since various feeds or finished products all have a certain odour, when feed loses its normal quality it produces various off-odours. ① Mouldy and rotten odour. This odour is emitted when feed has high moisture, vigorous respiration causes the temperature to rise, so that the feed heats up and begins to mould; in the plum rain season in summer, when feed management is improper, it is relatively easy for this to occur. ② Fermentation odour. When feed heats up, because part of the starch becomes alcohol, an odour similar to that of fermenting flour is produced. ③ Insect stink and other off-odours. When feed is harmed by certain storage insects, the secretions of the storage insects cause an insect stink. During transport or storage, feed may also absorb the odours of petrol, kerosene or other substances from the air, thereby lowering the quality of the feed.
1.4 Testing whether feed quality is good or bad through the sense of taste
Generally, feed raw materials and finished products of normal quality carry a certain fresh fragrance. Inferior ones may have off-odours, for example slightly heated and mouldy ones carry a sweet taste, more serious ones have a wine taste, and even more serious ones have a sour taste; having a bitter taste indicates complete deterioration. If a small amount of sand or mud is mixed in, chewing will produce a gritty sound. For the above sensory identification methods, one cannot judge the quality of the feed on the basis of only one point, but should make a comprehensive analysis from the test results.
2 Using the water dissolution method to identify feed quality
Put a small amount of sample in a clean cup, rinse with water, and observe whether there are sand grains at the bottom of the cup, whether the water used to rinse the sample becomes cloudy or changes colour, and whether the properties of the rinsed sample separate. This can identify those inferior feeds that have been dyed in order to make their appearance similar to high-quality feed.
3 Using the burning method and the indicator method to identify feed quality
Select suspicious grains from the sample or a small amount of sample and place them in a crucible to burn, observe the changes after burning and the odour during the burning process, and make a judgement. This can be used to identify the plant-based components and mineral components in animal protein materials. One can also use pH test paper and iodine tincture, and according to the colour change after the indicator is added to the sample, judge its acidity and alkalinity and whether it contains starch; this is mainly used to identify starch-containing substances added to protein materials, alkaline impurities in mineral feed, and non-amino components in amino acid feed.
4 Identification of the quality of feed raw materials commonly used in rural scaled farming
4.1 Corn
The normal sensory characteristics of corn are uniform grains, yellow or yellowish-white. The key to testing corn is the moisture content; preparing feed requires that the moisture content of corn must not exceed 14%, otherwise the feed quality will be greatly reduced. The specific methods for testing the moisture content are: ① Put the corn on the palm of the hand, and feel whether it is soft or hard by rubbing, pressing and pinching; if the grains are relatively hard, then the moisture is low, otherwise the moisture is high; ② Crushing with the teeth to identify: corn with a moisture of about 14% has its germ moisture shrunken and clearly sunken. When bitten with the teeth it shocks the teeth and gives out a crisp sound; corn with a moisture above 16% does not shock the teeth when bitten, but still makes a sound when crushed, and the higher the moisture content, the smaller the sound made when crushed, or even none at all.
4.2 Wheat bran
Wheat bran is a feed raw material among the by-products obtained by using various kinds of wheat as raw material and producing flour by conventional processes. When selecting it, first smell its odour; wheat bran with a sour taste, mouldy taste or fermentation taste must not be used; then observe its properties; it is required to be in fine crumb form, with a fresh colour, and when touched with the hand no moisture content should be felt (it should be less than 12.5%).
4.3 Soybean meal
Soybean meal is a feed raw material made from soybeans as raw material after oil extraction by the pre-pressing extraction method. Better-quality soybean meal is in the form of light yellow or pale yellow irregular fragments, with a consistent colour, no fermentation, mould, caking, insect damage or off-odour. However, newly produced soybean meal has a fishy smell. In addition, the moisture of the soybean meal selected should not exceed 14.5%, and it should scatter very well when grasped by hand; if the moisture is too high, it will feel sluggish when grasped by hand, and such soybean meal is not suitable for selection; if this kind of soybean meal has already been purchased, it should be dried in the sun and used only after the moisture has decreased, so as to avoid causing feed mould and other situations. When buying soybean meal, also note that soybean meal with much impurity should not be used; such soybean meal has low protein content and will affect feed quality. For soybean meal adulterated with sand and mud, 5%-10% stone powder or crushed corn, the identification methods that can be used are: ① Water immersion method. Take 25g of soybean cake (meal), put it into a glass cup containing 250mL of water and soak for 2-3h, then stir gently with a wooden stick; if it is adulterated, layering can be seen, with soybean cake (meal) in the upper layer and sand and mud in the lower layer. ② Iodine tincture identification method. Take a little soybean cake (meal) and put it on a clean white porcelain plate, spread it thin and flat, drip a few drops of iodine tincture on it, and after 1min, if some of the substances turn blue-black, it indicates that corn, bran, rice husk or other substances may be mixed in.
4.4 Fish meal
Fish meal is made from the processing scraps of aquatic products such as fish, shrimp and crab, such as fish heads, tails and internal organs, as raw materials, through drying and degreasing, crushing, or through cooking, pressing and crushing. The protein content of fish meal is above 50%, and fish meal is expensive; the amount added in compound feed is generally comparable to that of macro mineral additives, and its quality directly affects whether the feed quality is good or bad. ① Visually judge the colour and processing method of fish meal; fish meal dried artificially after degreasing has a relatively dark colour, brown, while fish meal dried naturally in the sun has a relatively light colour, yellow or greenish-white. High-quality fish meal shows slender muscle bundles, fish bones, fish eyes and fish flesh blocks, etc., and must not have parasites or mould. ② Smell: good fish meal has a fishy smell, and correspondingly produces a fishy stink and irritating stench as the degree of spoilage increases; some inferior products have an abnormal stench or a scorched taste. ③ Touch: after rubbing high-quality fish meal with the fingers, it is loose and soft in texture, showing a meat-orange appearance. Inferior fish meal or adulterated fish meal is rough in texture; after rubbing with the fingers one can observe its hardness, viscosity and foreign matter. Through the above 3 points of sensory identification one can judge the authenticity and quality of fish meal; if blood meal, sand grains, leather, salt powder, etc. are mixed in, they can be identified.
4.5 Amino acids
Whether the quality of amino acids is good or bad directly affects the quality of the feed. The two amino acids most commonly used in the greatest amounts are lysine and methionine. ① Lysine: it is in the form of white or brownish small granules or powder; the genuine product is odourless or has a slight characteristic sour taste, tastes sour when put in the mouth, feels uniform in texture in the hand; when put into fire and burned, when the lysine content is higher than 98.5% it burns up quickly and gives off an unpleasant special stench, like the smell of scorched feathers. Adulterated lysine, however, has an abnormal colour, an improper odour, and carries a pungent or aromatic smell, feels rough in the hand, has an astringent feel when put in the mouth, has obvious residue during burning, and after burning has no scorched feather smell. ② Methionine: it is white or pale yellow crystalline powder or flakes, with reflectivity; the genuine product has a special odour, tastes slightly sweet in the mouth, has no astringent feel, and feels smooth and greasy when rubbed in the hand; when put into fire and burned, when the methionine content is higher than 98.5% it burns up quickly, and after burning gives off an unpleasant special stench; adulterated methionine is yellow or grey, has very few crystals, an improper odour, has no sweet taste but a strange taste when put in the mouth, has an impurity-like astringent feel, feels relatively rough in the hand, does not burn up completely when put into fire, has residue, and after burning has no special scorched feather odour.
--------------------------------------
Very simple and also very practical
--------------------------------------
Thanks to the original poster
1.1 Using eyesight to identify the quality of feed
The main thing is to observe the feed's variety, form and colour. When testing, take a handful of the sample and place it on the palm of the hand or on white paper, spread it flat gently with the hand, focus the line of sight on a certain part of the sample, and identify it carefully, checking the uniformity, form, colour and lustre of the grains. For grain raw materials with husks, one can also observe the thickness of the husk, the condition of insect damage, the degree of plumpness and the amount of incomplete grains, etc. For certain varieties, one can even estimate the moisture content, for example with corn, one can observe its colour and the form of the germ; if the colour is bright, the germ is shrunken and hairless, and the grains are uniform with few broken grains, its moisture is generally below 15%; if the colour is dull and lustreless, the germ is not shrunken and is hairy, then its moisture may be above 16%. One can also judge from the colour whether the feed is new or old and whether it has been attacked by mould, for example good-quality feed has a fresh colour and good lustre; feed that has undergone high temperature or been stored for a long time has a dull colour and loses its lustre, and some is accompanied by caking; corn with gibberella disease is pink; the reproduction of penicillium and aspergillus can turn rice yellow.
1.2 Using the hand to feel the feed and judge its quality
That is, take the sample and put it in the palm of the hand, touch it with the fingers, and use the feeling on the surface of the hand to identify whether the grains are smooth or rough, then rub and press with the fingers to identify whether they are soft, hard, plump or shrivelled, or judge the moisture according to the temperature and specific gravity of the grains in the palm. For corn, one can also insert a fingernail into the germ; if it feels loose and soft then the moisture is relatively high, otherwise the moisture is below 14%. When identifying, one can also insert the hand into the feed; if it goes in easily and lightly, and the sound is smooth and bright, then the water content is low; if it is sluggish and difficult to insert, then the water content is high. For powdered feed, one can also grip the sample tightly with the hand; if it feels fluffy and rough, and scatters easily when released, then the moisture is relatively low. When touching feed with the hand, note that the fingers and palm should be clean, there must be no hand sweat, and the method of touch should be chosen according to the grain shape and characteristics of the feed.
1.3 Identifying feed quality through the sense of smell
Since various feeds or finished products all have a certain odour, when feed loses its normal quality it produces various off-odours. ① Mouldy and rotten odour. This odour is emitted when feed has high moisture, vigorous respiration causes the temperature to rise, so that the feed heats up and begins to mould; in the plum rain season in summer, when feed management is improper, it is relatively easy for this to occur. ② Fermentation odour. When feed heats up, because part of the starch becomes alcohol, an odour similar to that of fermenting flour is produced. ③ Insect stink and other off-odours. When feed is harmed by certain storage insects, the secretions of the storage insects cause an insect stink. During transport or storage, feed may also absorb the odours of petrol, kerosene or other substances from the air, thereby lowering the quality of the feed.
1.4 Testing whether feed quality is good or bad through the sense of taste
Generally, feed raw materials and finished products of normal quality carry a certain fresh fragrance. Inferior ones may have off-odours, for example slightly heated and mouldy ones carry a sweet taste, more serious ones have a wine taste, and even more serious ones have a sour taste; having a bitter taste indicates complete deterioration. If a small amount of sand or mud is mixed in, chewing will produce a gritty sound. For the above sensory identification methods, one cannot judge the quality of the feed on the basis of only one point, but should make a comprehensive analysis from the test results.
2 Using the water dissolution method to identify feed quality
Put a small amount of sample in a clean cup, rinse with water, and observe whether there are sand grains at the bottom of the cup, whether the water used to rinse the sample becomes cloudy or changes colour, and whether the properties of the rinsed sample separate. This can identify those inferior feeds that have been dyed in order to make their appearance similar to high-quality feed.
3 Using the burning method and the indicator method to identify feed quality
Select suspicious grains from the sample or a small amount of sample and place them in a crucible to burn, observe the changes after burning and the odour during the burning process, and make a judgement. This can be used to identify the plant-based components and mineral components in animal protein materials. One can also use pH test paper and iodine tincture, and according to the colour change after the indicator is added to the sample, judge its acidity and alkalinity and whether it contains starch; this is mainly used to identify starch-containing substances added to protein materials, alkaline impurities in mineral feed, and non-amino components in amino acid feed.
4 Identification of the quality of feed raw materials commonly used in rural scaled farming
4.1 Corn
The normal sensory characteristics of corn are uniform grains, yellow or yellowish-white. The key to testing corn is the moisture content; preparing feed requires that the moisture content of corn must not exceed 14%, otherwise the feed quality will be greatly reduced. The specific methods for testing the moisture content are: ① Put the corn on the palm of the hand, and feel whether it is soft or hard by rubbing, pressing and pinching; if the grains are relatively hard, then the moisture is low, otherwise the moisture is high; ② Crushing with the teeth to identify: corn with a moisture of about 14% has its germ moisture shrunken and clearly sunken. When bitten with the teeth it shocks the teeth and gives out a crisp sound; corn with a moisture above 16% does not shock the teeth when bitten, but still makes a sound when crushed, and the higher the moisture content, the smaller the sound made when crushed, or even none at all.
4.2 Wheat bran
Wheat bran is a feed raw material among the by-products obtained by using various kinds of wheat as raw material and producing flour by conventional processes. When selecting it, first smell its odour; wheat bran with a sour taste, mouldy taste or fermentation taste must not be used; then observe its properties; it is required to be in fine crumb form, with a fresh colour, and when touched with the hand no moisture content should be felt (it should be less than 12.5%).
4.3 Soybean meal
Soybean meal is a feed raw material made from soybeans as raw material after oil extraction by the pre-pressing extraction method. Better-quality soybean meal is in the form of light yellow or pale yellow irregular fragments, with a consistent colour, no fermentation, mould, caking, insect damage or off-odour. However, newly produced soybean meal has a fishy smell. In addition, the moisture of the soybean meal selected should not exceed 14.5%, and it should scatter very well when grasped by hand; if the moisture is too high, it will feel sluggish when grasped by hand, and such soybean meal is not suitable for selection; if this kind of soybean meal has already been purchased, it should be dried in the sun and used only after the moisture has decreased, so as to avoid causing feed mould and other situations. When buying soybean meal, also note that soybean meal with much impurity should not be used; such soybean meal has low protein content and will affect feed quality. For soybean meal adulterated with sand and mud, 5%-10% stone powder or crushed corn, the identification methods that can be used are: ① Water immersion method. Take 25g of soybean cake (meal), put it into a glass cup containing 250mL of water and soak for 2-3h, then stir gently with a wooden stick; if it is adulterated, layering can be seen, with soybean cake (meal) in the upper layer and sand and mud in the lower layer. ② Iodine tincture identification method. Take a little soybean cake (meal) and put it on a clean white porcelain plate, spread it thin and flat, drip a few drops of iodine tincture on it, and after 1min, if some of the substances turn blue-black, it indicates that corn, bran, rice husk or other substances may be mixed in.
4.4 Fish meal
Fish meal is made from the processing scraps of aquatic products such as fish, shrimp and crab, such as fish heads, tails and internal organs, as raw materials, through drying and degreasing, crushing, or through cooking, pressing and crushing. The protein content of fish meal is above 50%, and fish meal is expensive; the amount added in compound feed is generally comparable to that of macro mineral additives, and its quality directly affects whether the feed quality is good or bad. ① Visually judge the colour and processing method of fish meal; fish meal dried artificially after degreasing has a relatively dark colour, brown, while fish meal dried naturally in the sun has a relatively light colour, yellow or greenish-white. High-quality fish meal shows slender muscle bundles, fish bones, fish eyes and fish flesh blocks, etc., and must not have parasites or mould. ② Smell: good fish meal has a fishy smell, and correspondingly produces a fishy stink and irritating stench as the degree of spoilage increases; some inferior products have an abnormal stench or a scorched taste. ③ Touch: after rubbing high-quality fish meal with the fingers, it is loose and soft in texture, showing a meat-orange appearance. Inferior fish meal or adulterated fish meal is rough in texture; after rubbing with the fingers one can observe its hardness, viscosity and foreign matter. Through the above 3 points of sensory identification one can judge the authenticity and quality of fish meal; if blood meal, sand grains, leather, salt powder, etc. are mixed in, they can be identified.
4.5 Amino acids
Whether the quality of amino acids is good or bad directly affects the quality of the feed. The two amino acids most commonly used in the greatest amounts are lysine and methionine. ① Lysine: it is in the form of white or brownish small granules or powder; the genuine product is odourless or has a slight characteristic sour taste, tastes sour when put in the mouth, feels uniform in texture in the hand; when put into fire and burned, when the lysine content is higher than 98.5% it burns up quickly and gives off an unpleasant special stench, like the smell of scorched feathers. Adulterated lysine, however, has an abnormal colour, an improper odour, and carries a pungent or aromatic smell, feels rough in the hand, has an astringent feel when put in the mouth, has obvious residue during burning, and after burning has no scorched feather smell. ② Methionine: it is white or pale yellow crystalline powder or flakes, with reflectivity; the genuine product has a special odour, tastes slightly sweet in the mouth, has no astringent feel, and feels smooth and greasy when rubbed in the hand; when put into fire and burned, when the methionine content is higher than 98.5% it burns up quickly, and after burning gives off an unpleasant special stench; adulterated methionine is yellow or grey, has very few crystals, an improper odour, has no sweet taste but a strange taste when put in the mouth, has an impurity-like astringent feel, feels relatively rough in the hand, does not burn up completely when put into fire, has residue, and after burning has no special scorched feather odour.
--------------------------------------
Very simple and also very practical
--------------------------------------
Thanks to the original poster