Digestion and performance: acids, butyrates and the other gut health levers in feed

Behind “gut health” there are three things that can be described without a promise: digestion, which turns feed into nutrients; the gut lining, which absorbs them and acts as a barrier; and the gut flora, the microbiota, which stays in balance. In chickens as in pigs, all three are decided first in the feed: its digestibility, its buffering capacity, and what it leaves undigested for the bacteria in the gut. Gut health in poultry and in pigs therefore starts at the mill, in the formula, and gut health management in poultry starts with the feed a chicken is given.

The additives in this category work on those conditions. Acids lower the pH of the feed and of the stomach. Butyrates and tributyrin supply butyric acid, the main energy source of the cells lining the gut. Monoglycerides are molecules whose action on the membrane of certain bacteria does not depend on pH. The postbiotic and the probiotic supply lactic acid bacteria, inactivated or live. Tannins bind to proteins. The emulsifier helps the animal digest the fat in the diet.

None of these levers does everything, and they do not simply add up: stacking an acid, a butyrate and a probiotic does not give you the sum of their effects. The job is to choose the one that answers your problem, in your formula, at your production stage.

At weaning, everything changes at once: the sow’s milk is gone, solid feed becomes the only source of nutrients, piglets change pen and pen-mates. Feed intake collapses for a few days, while the piglet’s stomach does not yet produce enough acid to digest plant proteins on its own. Poorly digested protein reaches the intestine, where it feeds the flora you do not want. So yes, weaning can cause diarrhoea, and this is why.

That window is when post-weaning diarrhoea (post weaning diarrhea, or PWD) appears in pigs, often linked to the growth of an unwanted flora in the gut. Cold and draughts play their part too: a weaned piglet that is cold eats less and digests less well, which is why low temperature is a classic factor in post-weaning diarrhea in piglets.

Post-weaning diarrhoea is a disease: its diagnosis and care belong to the veterinarian. Linker products are additives and supplements for feed and drinking water, used within a farm’s programme. What feed can do is bring together the conditions for digestion to get off to a good start. That is the whole subject of piglet weaning, lever by lever:

• A feed that gets eaten: palatable, carrying the flavour of the creep feed forward, with flavours and sweeteners.
• A stomach that acidifies: a feed with controlled buffering capacity, acidified with Linkacid or, in pigs, Linkazoic.
• Less undigested protein: a digestible protein, at a level suited to the piglet’s age.
• Energy for the gut lining: butyrate from Linkasel or Linkatrib.
• Lactic acid bacteria and plant extracts: Linkabiome, Linkaflore, Linkatan, Linkalpha.
• And outside the feed: clean water within reach from the first hour in the pen, for instance acidified with Linkacid Prime L, the right temperature, pen hygiene. The drinking water completes the programme: weaning, through the drinking water.

Free butyric acid smells strongly and is absorbed very early: the whole point is to get it to where the gut lining uses it. An unprotected salt, sodium or calcium butyrate, dissolves in the stomach; a fat coating delays its release towards the intestine but dilutes the active; tributyrin, an ester, crosses the stomach intact and releases its butyrate in the small intestine, through the action of lipase. Linkasel covers the salts, Linkatrib tributyrin.

The choice depends on the gut segment you are aiming at, your pelleting temperature and the cost per unit of butyrate actually delivered: that is the tributyrin vs sodium butyrate question, which we work through with you on your formula.

Two feeds at the same pH can need very different amounts of acid. What decides is the acid binding capacity of the formula: the amount of acid needed to bring one kilo of feed down to a reference pH.

Limestone, phosphates and protein sources push it up; cereals and fats keep it low. A creep feed rich in protein and minerals is therefore much harder to acidify than a cereal-based grower feed: the same acidifier rate does not do the same job in both. Overdosing a low-buffering feed costs money for nothing and can weigh on palatability; underdosing a high-buffering one is the most common way to conclude, wrongly, that an acidifier does not work.

Each acid also has its own territory: formic and fumaric acids bring the pH down fast, propionic and butyric acids stay active further along. That is the case for a blend rather than a single acid, and the whole subject of organic acids in feed, one by one.

Send us your formula: we look with you at what drives its buffering capacity up, and what that changes for the choice of Linkacid grade and its rate.