Published online by Cambridge University Press: 02 September 2010
1. Four experiments, each with two groups of eight pigs, were performed in a controlled environment room equipped with two pens. One pen had straw as bedding and the other had slats. The animals were exposed to temperatures of about 17°C at the initial weight (20 to 25 kg). The temperature was lowered by about 1°C per 10 kg body-weight increase, to 8 to 12°C at the end of the fattening period (80 to 100 kg).
Animals on slats were kept 4·7 to 5·3°C below the calculated zone of thermoneutrality and the animals on straw 2·0 to 2·6°C above the lower limit of thermoneutrality. In Experiments 1 and 2 the animals in both pens received the same amount of food per day and in Experiments 3 and 4 animals on slats received more food to give the same body·weight gain as on straw. Feeding level on straw was about 93 g/kg0·75 per day.
2. In Experiments 1 and 2, body-weight gain on slats was reduced due to the lower effective temperature. After adjusting for feeding level, the reduction in daily gain was calculated as 18·5 and 11·8 g per °C below thermoneutrality. In Experiments 3 and 4 the extra food needed to maintain the same rate of gain on slats as on straw was respectively 18·1 and 45·5 g per °C below thermoneutrality.
3. Carcass length of animals on slats was less than on straw.