Orientation on techniques for reducing heat stress amongst lactating sows

摘要

The climatic requirement of the lactating sow is considerably different from the climatic requirements of her piglets. This leads to practical problems, because it is not (yet) possible to separate the piglet's microclimate form the climate for the sow. The temperature in the barn will in a majority of the time be higher than the upper limit of the comfort zone, which may cause heat stress for the sow. A high ambient temperature for the sow causes decrease of feed intake and thus loss of body weight and back fat and decreased milk production. In the present study two techniques for creating a microclimate for the sow were tested. The techniques were floor cooling under the sow and an air blower at the head of the sow. The floor cooling was situated in two pens under the front (shoulder and neck) of the sow's body. Under the steel plasticized metal slats a cold water circuit is welded. Cool water (about 14 deg C) flows into a close separated water circuit under the slats. With the air-blow technique the air was blown, creating airspeed of about 0.5 m/s around the head of the sow, also in two pens. In a preliminary study (April -October 1999) it was concluded that the cooling systems can practically be implemented in a farrowing pen without causing an uncomfortable situation for the sow and her piglets. During two batches (October -December 1999) sow feed intake, sow weight loss and piglet growth have been recorded for the two pens with floor cooling, the two pens with air blowers and two reference pens. The measured heat loss to the water in the floor cooling circuit was between 70 and 105 Watt per sow. The simulation software ANIPRO (Van Ouwerkerk, 1999) was used to make calculations of the upper limit of the comfort zone for the sows housed in the experimental pens. The cooling technique increases the calculated upper limit of the thermoneutral zone with 0.5 deg C for air-blowers and with 1 deg C for floor cooling compared to a situation without cooling technique.