Effect of ambient temperature and addition of straw or alfalfa in the diet on energy metabolism in pregnant sows

Abstract

Twelve pregnant multiparous Large White sows (Trial 1) were kept individually in respiration chambers for 35 days at ambient temperatures which changed (by 3°C steps) from 23 to 8°C and then from 8 to 23°C (3 days at each temperature). Sows (4 per treatment) were fed a basal diet (Treatment 1) or the basal diet supplemented either with wheat straw (Treatment 2) or alfalfa meal (Treatment 3). In Trial 2, four sows were maintained successively at 20, 14 and 8°C (8 days at each temperature). At each temperature, they were given 2.1 and 2.7 kg of basal diet (Trial 1, 4 days at each feeding level). Energy and nitrogen balances were carried out. Reduction of ambient temperature induced a curvilinear increase of heat production, the rate of change being as high as temperature or feeding level were low. Consequently, additional daily feed requirement for compensating the effect of cold varied between 45 to 85 g °C −1, according to ambient temperature or feeding level. Reduction of ambient temperature was associated with an increase of the efficiency of utilization of additional metabolizable energy (ME). Feedstuffs such as straw which are utilized with a low efficiency at thermoneutrality have, relative to standard feedstuffs, a higher energy value when animals are kept in the cold. Critical temperature was 20–23°C. Maintenance requirements of multiparous sows (425–435 kJ ME kg −0.75), which were comparable to those of primiparous females, are influenced by the activity of the animals. Nitrogen retention was depressed in the cold. Digestible and metabolizable energy values of wheat straw were 4.3 and 4.2 MJ kg −0.75 dry matter, respectively. Corresponding values for alfalfa meal were 8.5 and 7.4 MJ kg −1 dry matter.