According to Tim Kurbis from New Standard Ag, Inc. studies have shown that energy costs can account for between 13 and 15 per cent of operating costs.

One of the major areas for concern is in the method and efficiency of ventilating pig houses.

Not only does the efficiency of ventilation affect the energy costs and expense on the farm, but it also had a direct effect on animal production, the serviceability of equipment and the housing itself and also the health of the staff working on the farm.

Speaking at a recent presentation sponsored by the pig and animal production equipment company Nedap, Mr Kurbis said that one fan type in particular - a three-phase variable fan - for ventilation has several advantages in that it has a low motor cost and low maintenance cost. He added that it has an inherently high starting torque and high efficiency with no slip and therefore no heat loss.

He said that a three phase variable fan offers the pig farmer distinct savings in energy.

He said that for a mid-range speed fan, there is a difference of 150 watts in power between a static fan and a variable fan. He said that this could be a difference of 0.15 kW every 24 hours, 365 days a year producing 1,314 kW difference for each fan.

"If electricity is $0.09 per kW, this could produce savings of $118.26 for every variable fan per year," said Mr Kurbis.

He said it is important to test the performance of the fans by assessing the airflow per unit of energy expended and comparing different air flow ratios.

Importance of Position of Fans

The farmer also has to decide whether it is more efficient or cost-effective to have wall fans or chimney fans.

Mr Kurbis said that wall fans usually have a lower initial investment but they will have to fight against wind pressure and there could be more problems with odour in the surrounding atmosphere. He added that they are also limited in where they can be placed in the pig house.

Chimney fans will cost more initially to install but he said he considered that they had a better performance and better efficiency.

He said there is less exhaust smell and also they are less restricted in where they can be placed in the house.

Mr Kurbis said the comparison between variable fans and static fans on a timer also place an important part in the efficiency of ventilation, as variable fans, which allow for a continuous movement of air, allow a continuous controllable air pattern to be established.

He said that timed fans can cause surges in air flow and so he did not recommend them for base-level ventilation.

Mr Kurbis added that the placement of the fans and the inlets within the house is important for controlling the air flow.

"Ceiling air intakes allow proper placement and air control," he said.

The maximum distance for the air to travel at animal level is 40 feet (12.2 metres) and the inlets should be used to guide the incoming air and should never be fully opened. The desired air patterns should be controlled by the inlet and fan placement and the quantities of air should be calculated on the opening that is required.

Heat can be redistributed without having to recirculate the air. If the air does have to be recirculated, it indicates that there is a poor set-up or layout of the inlets and the fans.

Circulation of Air for Pig Health and Comfort

How the air is circulated and controlled has a direct effect on the efficiency of production. In group housing of sows, the air patterns and the quality of the air will directly affect the social patterns of the pigs - such as where they sleep and their dunging patterns.

"For sows housed in groups, air quality is critical for feed conversion and growth," said Mr Kurbis.

"Sow temperament depends on air quality."

And he added that high levels of ammonia in the house can effect gilt progression and it can effect reproduction and litter size and foetus weight in gilts, while temperature differences can affect feed consumption.

Bad airflows with draughts and rushes of air can also cause deaths of piglets as they try to get out of the airflow, and draughts in houses with a cooler ambient temperature can increase scouring in farrowing rooms and in the nursery area.

The effects on feed consumption and weight gain and growth have been directly calculated.

Mr Kurbis said that according to the Prairie Swine Centre, for every 1°C above the pig's thermo-neutral zone, feed intake can drop between one and two per cent and growth rates can drop by three per cent.

He added that temperatures that are too low in winter will cause the pigs to use their feed energy to maintain their body heat.

"Temperatures that are too high in the winter also raise energy costs," he said.

A lower level of ammonia and humidity in the house will also have a direct effect on the longevity of the equipment. The higher the levels, the greater chance of corrosion and breakdown.

Air quality in the barn will also affect the health of the workers.

Mr Kurbis said it has been shown that about a quarter of people working in pig houses have respiratory problems and this can mean the loss of days work through illness, adding further expense to production.

He said that with the numerous ways that air quality impacts the running of a pig house - from the worker health through to animal health and productivity and the longevity of equipment - it is essential to consider every aspect of ventilation.

Small changes, he said, can make a big difference to production and to costs.

July 2008