Behaviour and performance of lactating sows housed in different types of farrowing rooms during summer

Thirty mixed-parity Landrace × Large White sows were used to evaluate the effects of the type of farrowing room on 28-day lactation behaviour under tropical conditions during summer. The sows were allocated in a completely randomised design with three treatments with 10 replicates according to parity number and body weight, with each animal being considered an experimental unit. The treatments consisted of a conventional farrowing room (T1); a conventional farrowing room with floor cooling under the sow (T2); and a semi-outdoor farrowing room without a cage and with access to a fenced field (T3). The sows from T1 and T2 groups were exposed to mean maximum and minimum environmental temperatures of 25.7 and 21.0 °C, respectively, and the sows from the T3 group to average maximum and minimum environmental temperatures of 26.5 and 20.7 °C, respectively. The feed consumption of T3 sows was numerically higher than the T1 and T2 sows (+ 9.5% on average). The body-weight loss was influenced at 28 days (P < 0.10) by treatment, being that the T3 sows gained weight (+ 4.7 kg) while the T1 and T2 sows lost weight (− 11.9 and − 3.7 kg, respectively for T1 and T2). The T3 sows showed a higher percentual litter mortality than the T1 and T2 sows (3.2% vs. 0% vs. 7.8%, respectively for T1, T2 and T3 sows). From farrowing until day 28 of lactation, the T2 and T3 sows showed higher lactation efficiency when compared with the T1 sows (72% vs. 87% vs. 88%, respectively for T1, T2 and T3 sows). The T1 sows showed higher (P < 0.01) frequencies of visits to the feeder and drinker (+ 38% on average). The T3 sows spent more time (P < 0.01) at the drinker than T1 and T2 sows (23 vs. 23 vs. 32 min, respectively for T1, T2 and T3 sows). The T3 sows showed a higher (P < 0.10) frequency of nursing than the other treatments (+ 15% on average). T1 and T2 sows were found to spend more time (P < 0.01) performing other postures during 24 h than sows maintained in T3 (50 vs. 51 vs. 22 min/d, respectively for T1, T2 and T3). It is concluded that cooling of the floor under the sow in the conventional farrowing room or the use of semi-outdoor farrowing rooms improves the thermal environment and the lactation efficiency of the sows housed in hot ambient temperatures at 28-day lactation in the summer period, indicating an improved welfare.