Influence of high temperatures on performance and feeding behaviour of lactating sows

Twenty-four multiparous Large White sows were used to investigate the effects of ambient temperature (T) and dietary protein content (CP) on lactating performance. Sows were allocated to two main thermic treatments and two different diets according a factorial design 2x2. Temperature was maintained constant at 25 °C or varied of ±4°C around 25°C over 24 hours. Dietary protein content was either 14 or 17% and essential amino acids contents were similar in both diets. Photoperiod was fixed to 14 h of light and 10 h of darkness. The individual feeding behaviour of 11 sows was studied. No interaction between T and CP was observed. Cyclic T did affect neither performance of sows nor performance of piglets. At 25°C and 25±4°C, over the 21 days-long lactation, average daily feed intake of sows was 5191 g.Live weight and backfat thickness losses were 21 kg and 2.3 mm, respectively. Dietary CP content did affect neither lactating performance nor feeding behaviour. During the ad libitum feeding period (from the 7th to the 19th day of lactation), the number of meals was 7.1 per day with an average meal size of 962 g, daily ingestion duration and average ingestion rate were 50.8 and 126 g/min, respectively, when T was maintained at 25°C. At 25±4°C, the ingestion rate was significantly higher (164 g/min) but daily feed intake was similar (6801 g on average). Meal size and meal duration were not affected by T. Feeding behaviour was mainly diurnal (77 %) and especially when T was below 25°C for sows exposed at 25±4°C.