A note on the effects of forced air movement and environmental temperature on weight gain in the pig after weaning

Abstract

Twenty-six groups of four or eight pigs of mean initial weight 23-2 kg and mean age 84 days were exposed to environmental temperatures of 8, 12, 16 or 20°C under still-air conditions (wind-speed = 0-1 m.s" 1 ) or of 12 C C with wind-speeds of 0-45 or 0-8 m.s" 1 . The animals were fed at a fixed level close to three times their maintenance requirement, with water ad libitum, and were weighed weekly over a 7-week period. Variation in temperature between groups from 8 to 20°C had no significant effect on weight gain, but increasing wind-speed to 0-8 m.s" 1 at 12°C resulted in reduced weight gain.When pigs are exposed to a cold environment where the environmental temperature is below the critical level, the metabolic heat production is increased by the animal's thermoregulatory responses. When the animals are on a restricted feed intake, less feed energy is then available for growth in the cold and energy retention is reduced, most of the effect occurring in the reduction of fat deposition rather than of protein deposition (Close, Mount and Brown, 1978). Some reduction in the weight gain of growing pigs may therefore be expected when they are kept in the cold.Increasing the wind-speed at a given temperature also increases the thermal demand that is made by the environment on the animal, by leading to a rise in the convective heat loss and a rise in the critical temperature (Mount, 1978). The effects of cold have been investigated mainly in terms of changes in metabolic rate and energy balance, but it would also be useful to know to what extent weight gain is affected both by wind-speed and by environmental temperature when pigs are kept in groups under a customary husbandry regimen. The following measurements were made in an attempt to provide such information.Large White pigs of the Institute herd were weaned from the sow at 8 weeks of age, and then at about 10 weeks old sorted into groups of either four or eight animals including both females and castrated males; each group was on most occasions derived from one litter, but some groups were made up from two or three litters. Altogether, 26 groups were observed. 295

Effect of ambient temperature on energy metabolism in growing pigs

“…This is in agreement with results of Christison and Williams (1982) and Mount, Start and Brown (1980). In the present experiments, a temperature of 15°C resulted in a decrease of 60 g in daily gain in the first 6 days compared with 25°C.…”

Relationships between physical characteristics of the pig house, the engineering and control systems of the environment, and production parameters of growing pigs

“…These results agree with the propositions concerning the influence of the air velocity MOUNT et al, 1980). But these relationships are not in accordance with the results of T E xiER et al (1979), probably as a result of the interaction with the internal temperature, which was not always above 20 °C.…”

The influence of the thermal environment on the productivity of pigs

“…Younger animals are more susceptible to changes in air movement than older animals and small increases in air speed at the lower end of the scale are proportionately more effective in increasing heat loss than similar changes at high wind speeds (Mount, 1966;Mount and Ingram, 1965;Holmes and Mount, 1967). The increase in air movement above the level at which the boundary layer of air is disrupted usually reduces growth rate and Mount, Start and Brown (1980) demonstrated for groups of 23-kg pigs held at 12°C, that as air movement increased from 010 to 0-45 and 0-80 m/s daily growth rate decreased from 0-57 to 0-50 and 0-43 kg/day, respectively. the equivalent effect was 0-10 m/s whereas for groups of pigs it was 0-30 m/s (Verstegen and van der Hel, 1974).…”