Agriculture · Class 9-10 · Chapter 1 · Fifth section
Keeping food and fodder.
Growing a crop is a large piece of work, and so is not letting what you grew go to waste. In the last section you saw that about a tenth of the crop is lost in storage. Preserving feed is the technology against that loss, and this section is chiefly about the feed of a farm: feed for fish and feed for animals and birds.
1. Keeping means keeping the goodness
Preserving feed means processing and putting it away for later use in such a way that its quality and its food value stay as they were. The phrase inside the definition, keeping its quality and its food value, is what separates preserving from merely storing. Not having rotted is not the same as being good.
Four things spoil feed, and each has a limit of its own. Above 10 per cent moisture, fungus and insects appear. Above 65 per cent relative humidity, which is the moisture of the air, fungus and insects multiply. A temperature of 26 to 30 degrees is the most favourable of all for insects to breed, and at that heat the food value goes as well. And sunlight destroys vitamins within minutes, while oxygen oxidises the fat, bringing a stale smell and the insects with it.
A warning is worth giving here. In the last section the safe moisture for seed was 12 per cent; here the limit for feed is 10. They are two different numbers, and they are the ones most often confused in an examination.
three gaugesdrag the three sliders
When it will spoil
four enemiestap an enemy
The four enemies
The limit is 10%. Above it, fungus and insects appear. What to do: dry it well, keep it in an airtight container, and put the sacks on a wooden platform 12 to 15 cm above the floor.
The limit is 65%. If the air itself holds that much moisture, even dry feed draws water out of it, and then fungus and insects multiply. What to do: a cool, dry store and airtight containers.
Twenty six to thirty degrees is the most favourable of all for insects to breed, and at that heat the food value goes too. What to do: a cool place, and keeping vitamins, minerals and fresh fish frozen.
Sunlight destroys vitamins in minutes; oxygen oxidises the fat, bringing a stale smell and more insects. What to do: oily feed in an opaque or dark container, and vitamins and minerals in one that keeps out both air and light.
All four seen. Notice that the answers to the four enemies are four as well, and the same four each time: dry it, keep it cool, keep the air out, keep the light out.
check yourself
One question
In a store the feed is at 8% moisture, the relative humidity is 75% and the temperature 22 degrees. Is the feed at risk?
The feed's own moisture is fine, but one of the three conditions is enough on its own. Look at the humidity of the air.
Right. Breaking any one of the three conditions is enough. Here the feed's own moisture at 8% and the temperature at 22 are both fine; but the relative humidity of the air is 75%, well above the book's limit of 65. In air like that even dry feed draws water in, and then fungus and insects multiply.
The temperature really is in the safe range, but that is only one condition. The other two have to be looked at too.
A low temperature is not a problem but a help. The book's dangerous range is 26 to 30 degrees.
2. Dry or wet
For fish feed the book gives two separate rules, and they are opposites. Dry feed and dry ingredients go into airtight containers or sacks, in a cool dry place, and for dry fish feed the keeping time is no more than three months. Sacks go on a wooden platform 12 to 15 centimetres above the floor, with ash scattered round them against insects, and they have to be kept safe from rats.
Wet and sensitive ingredients follow another rule. Fresh small fish has to be fed at once or else frozen. Oily feed goes in an opaque or dark container at a controlled temperature, because light and oxygen spoil the fat. And vitamins and minerals go into a container that keeps out both air and light, and are kept frozen.
sort thema chip, then a bin
Which goes where
Pick up a chip, then drop it in a bin. Ask whether this is a thing to be kept dry, or a thing to be kept cold and dark.
Right. Next one.
Not there. Ask whether this holds water or oil, or whether it is dry already.
All in place. Dry: airtight containers or sacks in a cool dry place; for dry fish feed, no more than three months; sacks on a wooden platform 12 to 15 cm above the floor, with ash round them. Wet and sensitive: feed fresh small fish at once or freeze it; oily feed in a dark container at a controlled temperature; vitamins and minerals frozen, in a container that keeps out air and light.
3. Feed for animals and birds: five ways
The book names five ways of preserving feed for animals and birds, and the first two do the same work by opposite roads. Open the branches and look.
branchestap a branch to open it
Five ways of keeping feed
Preserving feed
Hay saved by drying
A grass of the legume family is best
Cut when it comes into flower
Dried to a moisture of 15 to 20%
Stacked on a platform or under a shed
Silage saved by shutting out the air
Maize, napier and guinea grass suit it
Cut while succulent, as it comes into flower
Pressed into an airless pit
Mixed with a solution of molasses
Sealed so that no air gets in
Straw what is left after threshing
After the grain is threshed out of paddy, maize and pulses
Dried to a moisture of 15 to 20%
Kept in a stack
By-products of grain and oilseed what the mill leaves
Rice bran
Wheat bran
Pulse husk
Oil cake
Feed made in a factory in three forms
Pellet
Mash
Crumble
Hay and silage are both ways of keeping grass, which is why they are the pair most often confused. Rotting needs water and air, both of them; take one away and it stops. Hay takes away the water and silage takes away the air. Drag the handle and see the two side by side.
two roadsdrag the handle
Hay, or silage
check yourself
Another question
Hay and silage are both ways of keeping grass. What is the essential difference?
The other way round. A legume grass suits hay, and maize, napier and guinea grass suit silage.
Right. There are two roads against rotting, taking away the water or taking away the air. Hay dries it to 15 to 20%; silage presses succulent grass into an airless pit with a solution of molasses and seals it.
The other way round. The pit belongs to silage, and the platform or shed to hay.
Molasses goes into silage only, never into hay. Nothing is mixed into hay at all; it is only dried.
check yourself
Last question
Above what moisture do fungus and insects appear in feed?
Five per cent is well below the limit, on the safe side. The book's limit is twice that.
Right. The book says fungus and insects appear above 10 per cent moisture. Be careful: the safe storage moisture for seed is 12 per cent, and 35 to 60 is where seed starts to germinate. Three numbers belonging to three different contexts.
Fifteen to twenty per cent is the moisture of hay and straw, not the limit for dry feed.
Thirty five per cent is the lower end of the range at which seed starts to germinate, and that belongs to the previous section.
At a glance
The definition. Processing and putting feed away for later use so that its quality and food value stay as they were.
Four enemies and their limits. Moisture at 10%, relative humidity at 65%, a temperature of 26 to 30 degrees, and light and oxygen.
Fish feed. Dry: airtight, cool and dry, no more than three months, on a platform 12 to 15 cm above the floor with ash around it. Wet: fresh fish at once or frozen, oily feed in a dark container, vitamins and minerals frozen and sealed from air and light.
Five methods. Hay at 15 to 20% moisture, silage in an airless pit with molasses, straw at 15 to 20%, the by-products of grain and oilseed, and factory pellet, mash and crumble.
Safety. Nothing poisonous is kept in a feed store. The book's measures against insects are all without chemicals: ash, a raised platform, airtight containers, drying and freezing.