Liquid feeding is a general term for mixing and distributing livestock-friendly feed in liquid form.

This kind of feeding has preferentially prevailed in pig fattening farms. Meal, vegetable products like crushed turnips, corn – corn cob mix or crude fibers are normally used for this type of feeding. Water or other nutrient liquids, like whey, are used as mixing liquids. Thanks to this feeding system, the animals are supplied with energy and the necessary liquid at the same time. Modern computer technology recalculates the feed mixtures on a daily basis and adapts them to the demand of the animals, considering breed, age, genetics and much more. Normally, the liquid feed is prepared by mixing in a mixing tank made of stainless steel. After its preparation, the feed is conveyed to the pigs through a pipe system by means of a  force pump. State-of-the-art technology is used for this process as well. An electro-pneumatic valve is installed in the pipe system at every feeding place. This valve is opened by computer control and a calculated feed portion is discharged into each trough. This system offers a lot of advantages, like great flexibility in feed compositions, simple pipe installations using PVC pipes, pipe systems with a large number of bends, underground pipes, central mixing for separated and spaced animal houses, easy retrofitting of feeding places, the pumping of several feed mixtures through one pipe only, rinsing and blowing out of feed pipes, arranging water programs and considerable labour savings and cost reductions. Liquid feeding allows many variations which have developed over the years. Today, modern feeding systems work as feeding-on-demand systems enabling the pigs to supply themselves with feed according to their demand.

For this purpose, each trough is fitted with a sensor which measures the filling level. If the sensor reports "empty" to the feeding computer, the trough will be filled automatically with new fresh feed. Below, we should like to present several systems and products of this category.

The feed pipe system consists of one or more cycles. The feed is pumped through the pipe to the troughs. The residual feed remains in the piping system. This residual feed is mixed with fresh feed by recirculation before the next feeding process starts.

The pipe system is completely filled with water (liquid) during the rest period. When the feeding process starts, the water is pressed out of the pipe with feed and collected in a tank. At the end of the feeding, the feed content in the pipe is pumped with water to the last troughs.

The feed is separated by separators (rubber stoppers). These separators are automatically infiltrated into the pipe system, if required. Thus, different feed mixtures can be available in the pipe system at the same time. Besides, the feed pipe can be emptied completely by pushing with water or compressed air, using a separator. Small feed portions can be transported between two separators in a targeted way to the desired trough.

Each trough is filled from 2 pipelines which transport always the same type of mixture (feed for preparatory feeding – feed for finishing). Computer-controlled blends from both pipelines ensure that the animals get age-adjusted feed every day. This procedure requires 2 mixing containers.

This system is based on the electronic interrogation of the trough filling level. If, when requesting the through by means of sensors, the process computer notices that feed is missing, it will automatically re-dose from stocks and mix new feed. Thus, the animals themselves determine their feed demand. Rationed feedings are possible at the end of fattening grow-outs.

This system leads us back to the beginnings of liquid feeding. Transmission lines have no return flow. However, there are sundry options for pipe rinsing. The feed remains in the pipe system during rest times. It is not being recirculated. All in all, this system is very simple, if the size of the group is suited and the animal house had been constructed accordingly.

These are pipe systems with diameters of up to 32 mm at most. The trend is towards these small pipe diameters for reasons of more exact dosing and improved pipe hygiene. The operation of such systems is associated to higher pump pressures. This system is not suited for all types of feed.

Phase feeding – this term already existed in the past. The feed was changed at certain phases of the animal growth (2 or 3 phase feeding). TEWE Elektronic has developed a system of „bio-phase feeding". With this system, a new feed composition - adapted to the demand of the animals - is calculated and mixed by a feeding computer every day.

This type of keeping means that the animals live in open houses with the option to retire to warmed boxes. The feed pipes are designed for operation in low temperatures.