The effects of environmental temperature and plane of nutrition on heat loss, energy retention and deposition of protein and fat in groups of growing pigs

Abstract

I. Eight groups each of four castrated male pigs, 25-30 kg initial body-weight, were kept for periods of 3 weeks in a calorimeter equipped as a pig pen and maintained at either 8" or zoo. At each temperature two feeding levels (g food/kg body-weight per d) were used, 45 and 52 at So, and 39 and 45 at 20'. Metabolizable energy, heat loss and nitrogen balance were measured.2. Heat loss was higher at 8" than at zoo and was independent of plane of nutrition, whereas at 20' the higher heat loss occurred at the higher plane of nutrition. Energy retention depended on both temperature and feeding level, and was highest at the 52 g feeding level at 8".3. N retention was not influenced by environmental temperature but varied with plane of nutrition (correlation coefficient = 094), the increase being 9.98 ( & 0.8) mg N per g food increase. The correlation coefficient between N retention and body-weight gain was also 0'94; body. weight gain was correlated with N retention rather than with fat deposition. Fat gain was reduced at the lower feeding levels and at the lower environmental temperature at the feeding level of 45 g/kg.4. The partial efficiency of energy retention at zoo was 66.5%. From this efficiency the maintenance requirement (at zero energy retention) at zoo was calculated to be 418 kJ/kgo*'5. At 8" the partial efficiency of energy retention was 99.4%.Calorimetric measurements have shown that, in addition to effects associated with body size and thermal insulation, the rate of an animal's heat loss is determined principally by two factors, the plane of nutrition and the environmental temperature. The environmental temperature also determines which of these two factors is primary : in the zone of thermal neutrality, the plane of nutrition is the chief determinant, with the higher heat loss occurring at the higher level of feeding, whereas under cooler conditions heat loss is dependent on the environmental temperature and the plane of nutrition has little effect. This relation has been demonstrated for heat production measured by indirect calorimetry in individual clipped sheep (Graham, Wainman, Blaxter & Armstrong, 1959) and in groups of pigs (Verstegen, 1971), and for heat loss measured by direct calorimetry in groups of pigs (Close, Mount & Start, 1971).In the direct calorimetric experiments on pigs each group was exposed to two consecutive planes of nutrition while the environmental temperature was held constant. In earlier work (Holmes & Mount, 1967), each group had been exposed to two consecutive environmental temperatures while the plane of nutrition was held constant.In both instances at the lowest environmental temperatures used (7 and 9O respectively) at a given level of food intake the rate of heat loss was increased significantly and the rate of energy retention (metabolizable energy intake less heat loss) reduced correspondingly.In both sets of experiments on pigs there was the possibility that the results obtained

Energy Metabolism of the Newborn Pig during the First 24 h of Life

“…The reasons for this dis crepancy would be that in Gentz's study, the piglets were kept at a higher environmental temperature (34 °C and starved for 2-3 h prior to the measurement. Moreover, this 34 °C temperature has been considered to be the critical temperature, i.e., the lower limit of the thermoneutral zone, of the single new born pig [15,17], This recommendation is confirmed by our findings, since, similar to the growing pig in which heat loss is indepen dent of food intake below the critical temper ature [19,12], V 02 of piglets kept at 31 °C are not affected by colostrum consumption.…”

Studies on the energy metabolism of the pregnant sow

“…The N retained by the animals was calculated from the difference between the N in the feed and that of the faeces, mixed urine and washings and the ammonia generated within the calorimeter. The latter was measured by the method described by Verstegen et al (1973). The energy retained (ER) by the animals was calculated as the difference between ME intake and heat loss, whereas fat deposition was calculated as the difference between ER and protein deposition.…”

Influence of low ambient temperatures on heat production and energy balance of single-housed growing pigs fed ad libitum: a comparison with group-housed pigs

“…The corresponding values calculated from equation (5) were 0.65 and 0.81. An improvement of k g under cold exposure has been reported by several authors [2,5,11,14,21] and indicates that TEF is partly used to meet energy requirements for thermoregulation. In addition, the present study and our previous results in group-housed growing pigs [16] indicate that the long term component of TEF is the most concerned in the variation of TEF or k g with ambient temperature.…”

“…One of the main adaptations of ad libitum fed pigs to low ambient temperature is increasing the energy intake so that the energy balance and growth performance can be maintained [1,4,7,8,10,14,15]. Additionally, an increased contribution of physical activity to total HP at low temperatures has been reported [16], as well as an improvement of energy efficiency [2,5,11,14,16,21].…”