The effect of ambient temperature on the thiamin requirement of growing-finishing pigs.

I. Three experiments involving sixty-two growing-finishing pigs from 28 to 90 kg bodyweight were conducted to investigate the effect of environmental temperature on the thiamin requirement of growing-finishing pigs. Three temperatures (zoo, 30' and 35") were used. 2. Under these experimental conditions, average daily weight gain indicated no effect of environmental temperature on thiamin requirement. By using erythrocyte transketolase (EC 2.2. I . I ) activity and its percentage stimulation by thiamin pyrophosphate (TPP stimulation per cent) as criteria, there was a significant effect of environmental temperature on the thiamin requirement of growing-finishing pigs. At 20", the thiamin requirement for maintaining maximum transketolase activity or minimum T P P stimulation per cent was found to be approximately 3'3 mg/kg diet; at 30°, the requirement was between 3'7 and 4.0 mg/kg diet. As estimated from erythrocyte transketolase activity, and the rate of 'TPP stimulation per cent increase, the thiamin requirement might be higher than 4.0 mg/kg diet at 35'. 3. There was a significant effect of environmental temperature on daily weight gain and food intake. The rate of weight gain and food intake decreased with increasing temperature. The efficiency of food utilization generally showed no significant differences among temperatures.