The influence of environmental temperature and plane of nutrition on heat losses from groups of growing pigs

Abstract

SUMMARY1. Rates of heat loss from 12 groups of pigs were measured over 4-week periods in a large direct calorimeter equipped as a pig pen.2. The levels of feeding in different groups were 34, 39, 45 and 52g/kg body weight per day, and the calorimeter temperatures were 7°, 12°, 20° and 30°C.3. At 12°, 20° and 30°C the rates of heat loss were related to the level of feeding.4. At 7°C the mean rate of heat loss was higher than at the other temperatures, and was not related to the level of feeding.

Models of heat production and critical temperature for growing pigs

“…Some authors (Close 1971;Close et al, 1971;Verstegen, Close, Start and Mount, 1973) observed no effect of feed intake on the heat loss below the critical temperature. On the other hand, Fuller and Boyne (1972) found a small but significant effect of feed level below the critical temperature although this effect tended to disappear at the higher live weights, about 80 kg.…”

“…This value was used in equation (15) to calculate a critical temperature. The positive mean errors for the wooden slatted floors Source Close et al (1971), Verstegen et al (1973), Close and Mount (1978) Single pigs Close (1971), Fuller and Boyne (1972), Close and Mount (1978) Grouped pigs Close et al (1971), Verstegen et al (1973), Verstegen and Van der Hel (1974) All data may be due in part to the assumed value of R fA5 = 0-23°Cm 2 /W being too low. If the experimental air temperature was less than the calculated critical temperature then equation (13) was used to give the predicted heat loss.…”

“…No data for air temperatures greater than 25°C were used because of the possibility of increased heat production due to hyperthermic reaction. Values obtained by Close (1971) for heat loss at 20°C were excluded because they were based on measurements for periods of only 6 h and were consistently lower than values obtained by Close, Mount and Start (1971) from measurements over 24 h. It is possible that the normal heat loss due to daily patterns of activity was not represented during the 6-h period. Values obtained by Close (1971) for heat loss at 20°C were excluded because they were based on measurements for periods of only 6 h and were consistently lower than values obtained by Close, Mount and Start (1971) from measurements over 24 h. It is possible that the normal heat loss due to daily patterns of activity was not represented during the 6-h period.…”

Thyroid hormones and thermogenesis

“…Thus, RMR is influenced by level of energy intake both in the period immediately after a meal and during the subsequent 24 h. This has been documented for periods of altered energy intake which extend from days to weeks, in many species including man (Apfelbaum c t a f . 1971; Dauncey, 1980), sheep (Graham et al 1959), pig (Close et al 1971;Dauncey & Ingram, 1979 and rat (Rothwell & Stock, 1979). The interaction between temperature and energy intake on metabolic rate 24 h after feeding has been examined in the model of the young pig mentioned earlier (Macari et af.…”

Metabolism during starvation/dehydration stress in two species of galagos

“…The main cause of depressed metabolism in this case has been suggested to be due to starvation and/or dehydration stress of different magnitudes. Studies showing depression in resting or basal metabolism have been conducted in a variety of domesticated animals like sheep (GRAHAM et al, 1959), pigs (BALDWIN & INGRAM, 1968;CLOSE et al, 1971), and camels (SHCMIDT-NILSEN et al, 1967;YAGIL et al, 1978) and in wild animals, e.g., dik-diks (KAMAU & MALOIY, 1983), jackrabbits (REESE & HAINES, 1978), voles (MOSIN, 1984), and American badgers (HARLOW, 1981). In most of these cases the need to decrease metabolic rate has been given as an energy saving response in order to stretch inadequate feed or water stores over a longer period of stress.…”