Minnesota, state in the Mid-West of the USA. Where the state's north is known for its beautiful woods and lakes, the south consists of fertile arable fields that will stretch beyond the horizon. It's ideal for crop farming, pig production - and wind energy production.

Pig farmer Matt Thome, owns the farm together with his father Gary and his brother Pat. It is located near the town of Adams. The Thome family use their 1,500 acre (607 ha) fields for the cultivation of soybeans and corn. Feed and manure are used very sustainably. The revenue of his crops is eaten by the pigs; the pigs' manure will go on the fields again.

The family owns a farrow-to-finish farm, but the breeding (utilising a PIC breeding programme) is operated by a different party. He, his brother and his father take care of the nursery and the finisher section. Spread out over his fields, Thome Family Farms had four brand new finishing houses built over the last couple of years. On the picture, the two silos to the right contain high energy, high protein feed; the three to the left contain low energy, low protein feed.

Each pig house has dimensions of 122 x 164 feet (37 x 50 m), each housing 2,400 finishers; the pig house is designed according to the principle of 'double wide tunnel ventilation' - it has two long parallel rooms. One is used for barrows and one for gilts, as Thome acknowledges their differences in growth pattern - gilts growing more consistently, and barrows having a rapid growth curve towards the end of finishing.

The efficient use of energy and feed is appreciated at the farm. A lot of software regulates mechanisms on-farm, like the constant measuring and adjusting of pig house temperature and ventilation. Pigs come in at about 35 pounds (16 kg) and are sold to Hormel meatpackers in nearby Austin, MN, at 270 pounds liveweight (122 kg).

Average pig weight is a tool that is crucial to the farm's management system. A sorting sluice in each room constantly weighs the animals and helps to obtain the average weight of the pigs in every pig house. Depending on animals being below or above average weight, they are directed towards the section providing mainly 'high energy, high protein' feed, or mainly 'low energy, low protein' feed. Since the whole pen is a one-way circuit, pigs can walk around and end up at the sorting sluice again quickly enough.

The farm provides feed ad-lib and in solid form, but it can be mixed with water at will by the pigs by nudging a valve. The animals have also a separate drinking trough at their disposal.

Crucial to keep this system going is the presence of this 'FeedSaver', an on-farm feed mixing instrument developed by FeedLogic. It links to the two different groups of feed silos outside and can mix the feed in any right proportion desired to fill the 21 feeders per pig room.

Two of the four new finishing barns are equipped with this technology - this way he can compare results with ordinary, non-sophisticated feeding methods and Thome says he can tell the difference.

Early in finishing, rations will contain more high energy, high protein feed than at later stages (moving from 90-10% to 10-90%); and the section for the smaller pigs will get fed more high energy, high protein feed as well. Two tubes are therefore used, for the two different feed rations - one linking to the section for the smaller pigs in the front; one directly linking to the faster growers in the back.

Thome says he is convinced his hogs do best when they feel well. Therefore he keeps them on 8 square feet (0.75 m2) per pig, which is above average in the US. He also allows the pigs to walk around freely. The animals appear calm and not stressed.

At the finisher section, the pigs reach an average daily gain of 2.7 pounds, which is about 1.22 kg. The quickest pigs leave the finishing barn after 80 days, having reached slaughterweight. On average, Thome comes in and checks the pig houses three times a day, but the computer systems will alert him whenever there is a problem.

As indicated, tailor-made ventilation is considered important in a region where the climate can sometimes be extreme - heavy rains, heavy winds, high average temperatures as high as 85 degrees F or 29 degrees C in summer or as low as 20 degrees F or -7 degrees C with excessive snow. This internal ventilation system will regulate indoor temperature when outside curtains are drawn in winter time.

In summer, the ventilation is regulated through tube ventilation, which generates a steady and pleasant flow throughout the day of 8 m/h (13 km/h).

Last but not least, outside, this device is a ground water monitoring port, connected to a field tile that surrounds the concrete manure holding pit. It is mandatory to have it applied next to Minnesota swine barns so state officials can come in and check manure leakage in the grounds.