National Hog Farmer is part of Informa PLC's Informa marketing department
This website is operated by one or more companies owned by Informa PLC, and all copyrights belong to them. The registered office of Informa PLC is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.
View all animal health »
View all our events »
Researchers: Lee J. Johnston, Brigit M. Lozinski, Mike Reese, Eric Buchanan, Adrienne M. Hilbrands, Joel Tallaksen, and Yuzhi Li, University of Minnesota West Center Research and Outreach Center; and University of Minnesota Department of Biosystems and Bioengineering Kevin A. Janni, Erin Cortus, and Brian Hetchler | January 8, 2020
Minnesota may be known for its long winters, Arctic temperatures and heavy snowfall, but short summers often burden the state’s pork production system.
Most pig houses are designed and built to protect the pigs from the cold temperatures in Minnesota, and little consideration is given to the cooling required during the hot summer in the state.
All types of pigs are susceptible to heat stress in summer, but sows are particularly sensitive before and after farrowing and during lactation.
Currently, there are several ways to cool sows during the farrowing stage of production, such as increased ventilation, evaporative cooling pads, drip coolers, nose and mouth coolers, and dietary changes. Each method provides a certain degree of lower temperature for the sow, but each method has disadvantages.
Therefore, researchers at the University of Minnesota West Center Research and Outreach Center and the University of Michigan Department of Biosystems and Bioengineering recently set out to study a different method to cool sows powered by renewable energy.
Their hypothesis is that compared to uncooled sows, sows cooled by solar systems will be more comfortable and efficient during heat stress and will improve the carbon footprint of farrowing operations.
Provided by the University of Minnesota West Center Research and Outreach Center A floor mat was installed in the front of the farrowing pen (left), and a cooling circuit was placed under the floor (right).
The front of the sow farrowing pen is equipped with a floor mat (left), and a cooling circuit is installed under the floor (right).
The two mirror farrowing rooms of cooling and control are equipped with 16 farrowing pens for this study. Ventilation is provided by a combination of wall fans and pit fans controlled by the thermostat in each room.
Each farrowing pen is equipped with a stainless steel deep bowl sow feeder; sow nipple drinker; and a nipple drinker for piglets.
The perforated floor under the sows is made of cast iron, while the floor under the piglets is braided with plastic coating. The piglet's creeping area also provides supplementary calories.
One room was designated as a control room and no supplemental cooling was provided for the sows. The cold room is the same as the control room, except that a cooling pad (Cool Sow, Nooyen Manufacturing) is installed on the floor below the sow, and the cooling pad is connected to the cooling circuit. A separate nipple drinker provides chilled drinking water for the sows.
A liquid-to-liquid heat pump is used to cool the water in the closed circuit to approximately 65 degrees Fahrenheit. The pump circulates cooling water to each farrowing pen in the parallel circuit so that each pen receives cold water at a similar temperature.
The sow lying on the cooling floor transfers heat from the body to the floor, and then transfers this heat to the cold water circulating in the cycle.
The warm water leaving the floor returns to the heat pump, where it is cooled and circulated back to the floor inserts in the closed loop system. The heat pump also cools the sow's drinking water to about 60 degrees.
The cooling system contains a buffer water tank that serves as a cooling water reservoir to ensure continuous cooling water is provided to all 16 farrowing pens in the cold storage room.
If the heat rejection capacity of the heat pump is overwhelmed, the fan coil unit included in the system will extract the excess heat and discharge its exhaust gas outside the barn.
As part of the supplementary project, the heat extracted from the sow cooling circuit is transferred to a separate independent system that circulates hot water through mats located in the piglet’s crawling area.
The entire cooling system is powered by a 20-kilowatt solar array installed outside the barn. The solar cell array consists of 60 solar photovoltaic panels and two inverters.
Maintaining conditions and heating 84 mixed parity, hybrid female sows were used to evaluate the efficacy of the solar cooling system. The sows were delivered in three parts from June to August 2017 and 2018. When they were moved into the farrowing room around the 109th day of pregnancy, they were randomly assigned to the control or cooling room within the parity.
During the first test of the cooling system (June 2017), the cooler than expected weather did not provide continuous heat stress to the sows, so the heater was operated in the farrowing room to keep the room above 75 degrees, To ensure that the sow is under heat stress.
Groups (n = 41 control sows and 43 cold sows) were studied in the summer months. Measure the power consumption of all systems (ventilation, piglet heating, lighting and cooling) and record the performance of sows and piglets during lactation.
Provided by the University of Minnesota West Center Research and Extension Center. These are solar panels (20 kW) installed at the University of Minnesota West Center Research and Extension Center to power the sow cooling system.
These are solar panels (20 kilowatts) installed at the University of Minnesota West Center Research and Outreach Center to power the sow cooling system.
More power The cooling room always uses more power than the control room. The cold room uses 79.6 kWh per day, while the control room uses 26.4 kWh per day for the entire delivery group. Solar panels generate an average of 91 kWh per day.
It is more comfortable for sows to be kept in a cool room, with lower breathing rate, 59.1 vs. 90.9 breaths per minute (Figure 1); higher feed intake, 11.6 pounds and 9.9 pounds per day (Figure 2); Compared with the sows in the control room, they lost 31.3 lbs and 47.4 lbs during lactation. The number of litters at birth and at weaning and the weight of piglets at weaning are the same in each room.
Courtesy of the University of Minnesota West Center Research and Outreach Center
The cooling system (cooling floor and cooling drinking water) and piglet heating system studied effectively reduced the heat stress of lactating sows, but did not improve the production performance of the pigs. In addition, the total electrical energy required by these systems is more than 2.5 times that of traditional nursing house systems without sow cooling.
Further analysis Although the sow cooling system studied in this project can significantly reduce the heat stress of farrowing and lactating sows, it does not completely eliminate heat stress. Reduced heat stress in sows does not improve litter size at weaning or the growth rate of suckling pigs.
Therefore, the cost of installing and operating the cooling system will not be returned to the pig farmers through increased income.
At present, researchers do not recommend commercial installation and operation of the cooling system studied in this project; however, the impact of cooling drinking water should be further evaluated in an independent study. Compared with the cooling floor in the existing barn, the installation of cooling drinking water is easier and more economical.
Researchers: Lee J. Johnston, Brigit M. Lozinski, Mike Reese, Eric Buchanan, Adrienne M. Hilbrands, Joel Tallaksen, and Yuzhi Li, University of Minnesota West Center Research and Outreach Center; and University of Minnesota Department of Biosystems and Bioengineering Kevin A. Janni, Erin Cortus, and Brian Hetchler. For more information, please send an email to Johnston.
More information about text format