Performance and carcass quality of growing-finishing pigs submitted to reduced nocturnal temperature

During summer months, elevated barn temperature reduces pig growth rate by decreasing feed intake. Two trials were conducted over two summers to evaluate the effect of reduced nocturnal temperature on the performance and carcass quality of growing-finishing pigs. Control rooms had a typical temperature setpoint while the temperature setpoint for treatment rooms was 6°C lower. In Saskatchewan, a reduced temperature setpoint resulted in a lower nocturnal room temperature (1.6°C cooler over eight weeks), while it had no influence on room daytime temperature. The average daily temperature fluctuation in treatment rooms was increased by 2.1°C. The lower nocturnal temperature also resulted in a higher relative humidity (+3%) and lower CO2 and NH3 concentrations. During trial 1, pig average daily gain (ADG) in the treatment room was increased by 5.2%. For trial 2, feed intake was 3.2% higher in treatment rooms, which increased ADG by 2.1% on average over eight weeks. The ADG increase averaged 3.6% during the last four weeks of trial 2. However, no statistical differences were found for pig performance, feed conversion, and backfat thickness (P > 0.05). The results suggest that healthy pigs are not negatively affected by a large daily temperature fluctuation (up to 14.8° C) as long as this fluctuation is progressively achieved.