Liquid feeding systems are all automated now

In the second article in our series on liquid feeding, Steve Stokes of HFS discusses the equipment used and different feeding methods

The principle of liquid feeding is very simple, the feed ingredients (any combination from a simple meal-and-water ration to a complete multi-feed ration made from straights) are weighed into a feed tank (one at a time). This is achieved by having the tank – its size determined by the quantity of pigs to be fed and the feeding method used – mounted on weigh cells. The feed ingredients, depending on their form, are generally augured, pumped or gravity fed into the tank in the required quantities, and then blended thoroughly by a mechanical agitator/mixer.

Unlike most dry feeding, liquid feed is stored away from the pigs in the feed tank ready for sending to the feeding trough when required. The mixed cocktail of dry and water/liquid feed ingredients is now a liquid feed ration ready to be weighed out and pumped to the pigs down a pipeline that runs from the tank. At each trough, an automatic valve controls the feed being delivered, and the whole system is run by a controller.

In the past (pre-1970s), this was all done manually, and mainly by guesswork as weighing equipment wasn’t widely available, but the pigs still grew well. Since then, pretty much when HFS started, the ability of liquid feeding equipment has progressed by utilising weighing and computer technology to provide fully automated systems to feed pigs consistently the correct rations and amounts, as and when required, recording all the data accurately.

Set meals
Before full automation, a simple method evolved to minimise labour input of feeding all the pigs together at specific times of the day; once, twice or even three times a day into a trough in each pen that was sufficiently long enough to enable all the pigs to stand shoulder-to-shoulder for feeding. Today, this is known as “restrict feeding”, much the same as our meal times – breakfast, lunch and dinner – where we all sit down together to eat.

Restrict feeding is generally a very flexible operation, a defined process enabling many groups of pigs/rations to be fed from one feed tank as the pigs’ feed is based on set feed curve/s where the exact amount of feed is prepared and then fed out to the pigs. Once a group of pigs has been fed, the system is ready to feed the next.

However, trough length can be a factor. For example, a pen of 15 finishers would require 4.5m of trough, which doesn’t always fit with existing penning (in a new house it’s not a problem). But having all the pigs in a line at feeding does provide a useful visual check on pig condition.

Feeding out to the pigs by sticking rigidly to a feed curve has tremendous advantages in feeding certain stock, but where maximising intakes are desired, having no automated feedback on voluntary intakes can require tweaking the curve(s).

Ad-lib feeding
As automated technology evolved, labour input was now no longer an issue and feeding little and often was made possible. This requires a trough length that is considerably shorter than restrict feeding (akin to a dry feed hopper), as the feed is delivered to the pigs on demand, aided by a sensing/level probe mounted in each trough. This probe informs the controller when the trough is pretty much empty and is ready to accept another dose of feed.

Topping the trough up on demand makes it an almost living thing that creates a stimulus (noise and smell of the feed being delivered), continuously reminding the pigs about food. Today this is known as ad-lib feeding, similar to a buffet where we can make numerous visits to a table of nibbles.

Unlike restrict feeding, ad-lib is not a defined process as intake levels can vary on a daily basis depending on many factors like temperature, humidity, or the pigs may simply be a little more or less hungry today.

Therefore, as we feed out to the pigs, on their demand, we’re never too sure how much feed the pigs want/need over a given time. To overcome this, we prepare a set amount of feed that’s fed out to the pigs as they require, and when this feed has been consumed, we simply prepare another batch. Operating this way does lose the flexibility of utilising the feed tank for feeding other groups/rations, but having a dedicated system focused on being able to feed out when required pays dividends significantly with pig performance.

Trying to operate a more flexible system by having a defined procedure like restrict feeding does negate performance, as predicting the amount of feed to be prepared by using info gleaned from empty troughs and feeding behaviour is not wholly satisfactory, and ends up making either too much or not enough feed at that time.

Systems that feed on demand make controlling intakes by adhering to a feed curve simple, and although they can operate 24/7 (hibernating when troughs are satisfied), feeding within designated times throughout the day and night (feeding windows) allows intakes to be monitored all the time. This not only improves pig performance (perfect for maximising intakes) and their behaviour, but has a benefit with trough and pen hygiene as the pigs keep the feeding area clean.

Ad-lib feeding provides an automated feedback on voluntary intakes (in real-time) giving another level of management information, which is invaluable for certain stock.

> In the final article in this series we look at the different feeding systems that can be employed for different classes of pigs

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