Enzymes in Poultry Feed: Phytase, Xylanase and When They Pay

What the bird cannot break down on its own

A chicken's gut makes plenty of enzymes for the easy parts of a meal. Starch, most protein and fat are broken down without much help. The trouble starts with two things inside plant seeds: a store of phosphorus locked up as phytate, and a family of fibres called non-starch polysaccharides. The bird makes little or none of the enzymes that free them, so a large share passes through the gut untouched.

Phytate is the one that matters most to a feed-maker. It binds phosphorus so tightly that the bird cannot use much of the phosphorus in maize and soya on its own. The exact share depends on the ingredient, the variety and the harvest year, so treat any single figure you read with care. What it means on the farm is simpler. Part of the phosphorus you think you are feeding never reaches the bird, and the miller tops it up with a mineral phosphate that you pay for by the kilo. Our feed formulation basics article explains how that top-up gets into the formula in the first place.

Non-starch polysaccharides work differently. They are fibres that dissolve in the gut and turn the contents thick and sticky. That slows digestion, traps nutrients and leaves wetter droppings, which makes the litter harder to keep dry. Wheat, barley, rye and rice bran carry the most of them.

Phytase and the phosphorus you already paid for

Phytase is an enzyme that cuts phytate and releases the phosphorus inside it. Added to a maize and soya ration, it lets the bird absorb more of the phosphorus that is already there. That has two practical effects. A formulator can lower the amount of mineral phosphate, such as dicalcium phosphate, and still cover the bird's requirement. And less phosphorus leaves the bird in the droppings, which matters on crowded farms where manure piles up near the house.

Do not cut the mineral phosphate on your own. Phosphorus and calcium work together in bone, and a bird short of either shows it in weak legs and slow growth. Any change to the mineral phosphate has to come from whoever writes the formula, using the enzyme's activity figure. If you buy a feed that already contains phytase, the miller should have done that sum. If you mix your own, ask a nutritionist before you change a single kilo of phosphate, and read our mixing article for the other checks a home mix needs.

Xylanase, glucanase and the wheat and bran question

Xylanase breaks down the arabinoxylan fibres found in wheat, rye and wheat bran. Beta-glucanase does the same job for the beta-glucans in barley and oats. Both reduce the thickness of the gut contents, which lets the bird reach more of the starch, protein and fat that the fibre was wrapping.

The benefit depends on the ration. A maize and soya feed carries little of these fibres, so an enzyme aimed at them adds little. A feed built around wheat, or a cheap ration with a large share of wheat bran, is where xylanase earns its place. The drier droppings are usually the first thing farmers notice, and the rains make that a real gain. Ghana's wet season turns litter to paste quickly, so a feed that keeps the droppings firm is worth more than the figures on a spec sheet suggest.

Be careful with the claim, though. A thinner gut does not make a poor feed good. It helps a sound ration work harder, and it has nothing to say about a ration short of energy. If you are using cheaper alternatives to maize, check the ration before you reach for an enzyme.

Heat kills enzymes, so ask about pelleting

An enzyme is a protein, and proteins fall apart at high temperature. Pelleting means steaming the mash and pushing it through a die, and the temperature in that step can be high enough to destroy an unprotected enzyme. The lost activity does not show on the bag. You only see the damage later, in the birds.

Ask the miller two questions. Is the enzyme added before or after pelleting? And is it a heat-stable or coated product? If it goes in before and is not stable, the bag may contain much less active enzyme than the label implies. Some mills spray the enzyme on after pelleting to avoid the problem. Mash feed skips the heat step altogether, but mash is dustier, birds waste more of it, and the enzyme still has to be mixed evenly through the batch.

Storage matters too. Enzyme powders lose activity in heat and damp, so a bag left in a hot corner for a month is not the product you bought. Keep it sealed, cool and off the floor, like any other sensitive feed input.

Which enzyme for which feed

The table sets out the enzymes most often seen on a feed label or in a supplier's list. Use it to match the enzyme to the ingredients in your ration, not the other way round.

A multi-enzyme blend sounds like good value, but it only pays if your ration needs most of the enzymes in it. Paying for xylanase on a maize and soya feed is paying for a fibre you do not have. For the protein side of that table, our protein sources article covers the soya and fishmeal choices that decide whether a protease is worth anything.

The sum that decides whether it pays

Enzymes are sold by the tonne, and a tonne is a lot of feed to think about on a small farm. Work it out per tonne first, then per bird. The saving is the amount of an expensive ingredient you can take out, multiplied by its price. The cost is the enzyme's price for a tonne. The enzyme pays if the saving is bigger.

Say your nutritionist can take out 4 kg of mineral phosphate per tonne after adding phytase, and the phosphate costs GH₵ 6 a kilo. That is a saving of GH₵ 24 a tonne. If the phytase adds GH₵ 15 a tonne, the net saving is GH₵ 9 a tonne, or GH₵ 90 across ten tonnes. Those numbers are invented for the sum, and your nutritionist will work with your real prices and ingredients. The method is the part to keep.

Ninety cedis across ten tonnes is not a reason to celebrate. It is a reason to check whether the enzyme also lifts weight or lay, or cuts the feed you need per kilo of birds. If it does both, the sum changes. If it does neither, the saving is small enough that one error in the formula can wipe it out. Our feed conversion article shows how to measure that second number on your own birds.

When it pays, and when it wastes money

Enzymes earn their keep in a few situations and are poor value in others. Decide before the sales representative arrives with a sample bag.

• It pays when the ration carries a large share of wheat, barley or bran, and those grains cost less than maize.
• It pays when mineral phosphate is a big line on the feed bill and a nutritionist can cut it safely.
• It pays when droppings and litter are a constant problem, especially through the rains.
• It wastes money when the ration is maize and soya only, and the enzyme targets fibres that are not there.
• It wastes money when the feed is a small batch, the store is hot, and the enzyme sits open on a shelf.
• It wastes money when it is added to a feed the miller already supplemented in full.

The common thread is that an enzyme is a tool for a specific gap. If you cannot name the gap, you are not ready to buy the tool.

Mistakes that throw the enzyme away

Most enzyme losses come from handling rather than from the product. A good enzyme in the wrong place is an expensive way of feeding protein to the bin.

1. Adding the enzyme to a wet mix and leaving the mix to stand before it goes into the feeders.
2. Putting an enzyme that is not heat-stable into pellets that are steamed at high temperature.
3. Storing the powder in a hot shed next to the feed bins.
4. Cutting the mineral phosphate without a new formula, which leaves birds short and makes the enzyme look useless.
5. Using an enzyme as a rescue for a feed that is mouldy, short of energy or badly mixed.

How to see the effect on your own birds

Enzymes do not show themselves as dramatically as a vaccine reaction. You see them in small numbers, over time. Run a two-pen comparison, and add three measurements that suit enzymes in particular.

• Litter wetness, scored once a week at the same spots near the drinkers, on a simple scale from dry to sticky.
• Weight of a fixed sample of birds every week, on the same scale and at the same time of day.
• Feed used per pen per week, so you can work out feed conversion for each pen rather than the house as a whole.

Run the comparison for at least one full feed phase. A two-week look in the grower stage tells you very little about a laying flock, and a single weighing day can be thrown off by one bad sample.

Our view from the hatchery side

We are a hatchery, so the feed question reaches us late. By the time a farmer phones about slow growth or wet litter, the chicks have been in the house for weeks and the feed has been running for a while. The buyers who do best tend to share one habit. They know what is in their feed, and they can say why each thing is there.

An enzyme cannot fix a ration that is short of energy, short of protein or badly mixed. It works on what is there. Start with a sound formula from a miller who will show you the sheet, the same formula each batch, and clean water and dry litter in the house. Then ask whether an enzyme would pay, and let the sum decide.

If you are starting a new flock, our broiler chicks and layer chicks pages set out the birds we hatch, and the prices page shows current starting prices. For a question about a specific feed, your nutritionist is the right person. For the chicks, WhatsApp +233 24 915 1503 is the quickest route, or use the order form.

A checklist before you add an enzyme

Work through this list with the miller or nutritionist before the first bag is opened.

• Get the ration's ingredients by weight, from the formula sheet, not from memory.
• Get the enzyme's activity per kilo and its heat stability in writing.
• Confirm whether the enzyme goes in before or after pelleting.
• Have a new formula from a nutritionist before any change to the mineral phosphate.
• Work out the saving per tonne, and the net saving after the enzyme's price.
• Set up a control pen or keep a clear before-and-after record.
• Store the enzyme sealed, cool and dry, and use it before the date.

Questions farmers ask