Cooling innovations for loose farrowing pens in summer

The summer environment is a high risk time in loose farrowing systems as sows and piglets share cooler areas of the pen, resulting in piglets being at risk of being overlain (Morrison and Baxter 2014). The aim of this experiment was to assess piglet and sow lying behaviour and growth and survival of piglets in a SWAP (Sow Welfare and Piglet protection) loose farrowing system that included cooling innovations. The hypothesis was that the piglets would spend more time in the creep area in the cooled treatments resulting in improved piglet survival and growth.

The experiment was conducted over four time replicates utilising 190 mixed parity sows (Large White × Landrace PrimeGro™ Genetics, Corowa, NSW, Australia) in open-sided, naturally ventilated sheds. A 2 × 2 factorial design was used with the main factors being: (1) cooling (standard pen v. cooled tiles in creep and fan in nest; a 30cm fan was attached to the creep and airflow directed over the nest area and three ‘cool’ tiles covering the whole creep area (MIK International, Germany), and (2) floor type (solid v. slatted nest). The treatments were: (1) standard pen/solid nest; (2) standard pen/slatted nest; (3) cooled pen/solid nest; and (4) cooled pen/slatted nest. All floors were plastic. The cooled treatments were activated 4 days post-birth when the ambient temperature was greater than 25°C and remained on throughout lactation. The surface temperature of the cooled tiles was ~2°C cooler than the surrounding area. The total number of piglets born, number of piglets born alive and number of piglet deaths were recorded for each litter. Piglet mortality was calculated for each litter and live weights of litters were recorded at birth and weaning (~24 days of age). The location of the sow and piglets was recorded by direct observation scan sampling on a daily basis (1300 h) over lactation. The internal shed temperature was recorded from in situ temperature loggers located on the wall of the shed immediately before the behaviour observations. The scan data were converted into percentage of the sows and litter in each location. Sows were assigned to either the nest or dunging passage. Piglets could be in either in the creep, nest or dunging passage area. Univariate GLM analysis (SPSS v21.0, IBM, Armonk, NY, USA) was undertaken using each sow/litter as the experimental unit with the sow as the blocking factor. Differences in piglet location at different temperature ranges were analysed (range from less than or equal to 23.8°C to greater than 36°C) and the results are shown in Table 1.

Table 1.  Piglet survival, number of piglets weaned and growth performance

There were no significant (P > 0.05) interactions between treatments or differences in location preference of the sows. There was no significant difference (P > 0.05) in the location preference of piglets in the control and cooled treatment up to 36°C. Above this temperature, there was a greater proportion of piglets in the cooled creep area; however, this did not improve piglet survival and growth as there was a trend (P < 0.1) for higher piglet mortality and reduced weaning weight in the cooled treatment. There was no significant (P > 0.05) effect of floor type on sow or piglet location preference. Therefore, based on these results, our hypotheses was not proven and further research is warranted to assess alternative cooling strategies in loose systems in open-sided, naturally ventilated sheds.