CANADA - Conversion of gestation sow housing from stalls to group systems signifies a major shift for the recently revised Canadian Code of Practice for the Care and Handling of Pigs. One specific study at Prairie Swine Centre aimed to investigate management options that would take advantage of potential merits of group sow housing.
One such advantage may be, sows housed in groups can interact with one another and exhibit thermoregulatory behavior (e.g., huddling), potentially tolerating temperatures below the lower critical temperature (LCT).
Allowing room temperature to drop below this LCT will require additional feed to maintain the sow’s body condition and weight gain over the gestation period.
Other issues anticipated with group-housed sows include the potential for higher activity levels and aggression among sows. These problems may be worsened when sows are put on a restricted feeding program, which is a common practice for gestating sows, in order to maintain optimal body condition. The sensation of feeling “full” is improved with high-fiber (high heat increment) diets.
These diets are also known to reduce the urge to feed continuously, reduce overall activity, and repetitive behaviour in sows. Specifically, dietary fiber increases heat production in sows without increasing digestible energy. Therefore adding fiber to the diet can be a means of reducing activity and limiting aggression in sows under lower barn temperatures.
If group-housed sows can maintain body condition and weight gain at temperatures lower than currently being maintained in sow barns, without the need for additional feed, the potential exists to significantly reduce energy costs associated with heating and ventilation.
This study set out to develop an operant mechanism allowing sows to control their own environmental temperature. Two barn rooms were configured for group sow housing, with each room containing 28 gestating sows. One room was operated at a typical set-point temperature (16.5°C) while an operant mechanism was installed in the other room, allowing the sows to control the temperature. In addition, the impact of high heat-increment diets fed to the sows was also examined.
Results from the first phase of the project, controlled environmental chambers, indicate sows fed with a high heat-increment diet tended to maintain relatively lower temperatures (12.5 °C on average) compared to gestating sows fed a standard gestation diet (13.4 °C).
In addition, sows fed a high heat-increment diet had no considerable effect on their performance and physiological response, when exposed to relatively colder temperatures.
Results from the second phase, gestation room trials, have shown that sows could tolerate temperatures as low as 9 °C, which is significantly lower than the set-point typically maintained in gestation barns (i.e., 16.5 °C).
Furthermore, it was confirmed that maintaining gestation rooms at a lower environmental temperature would result in considerable reduction in energy consumption (as much as 78 per cent) related to heating and ventilation. At 2016 energy prices this 78% reduction in energy costs would translate into approximately $2.75/hog during the heating season.
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