.. ..., ....,PAPERS & ARTICLES_ Timing and causes of piglet mortality in alternative and conventional farrowing systems J. N. MARCHANT, A. R. RUDD, M. T. MENDL, D. M. BROOM, M. J. MEREDITH, S. CORNING, P. H. SIMMINS Veterinary Record (2000) 147,209-214 J. N. Marchant, BSc, PhD, CBiol, MIBiol, A. R. Rudd, BSc, MSc, PhD, GIBiol, M. T. Mendl, MA, PhD, D. M. Broom, MA, PhD, FIBiol, M. J. Meredith, BSc, MA, BVetMed, PhD, MRCVS, Department of Clinical Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 OES S. Corning, BSc, P. H. Simmins, BSc, PhD, ADAS Terrington, Terrington St Clement, King's Lynn, Norfolk PE34 4PW Dr Marchant's present address is School of Agriculture, De Montfort University, Caythorpe Court, Caythorpe, Grantham, Lincolnshire NG32 3EP Dr Mendl's present address is Department of Clinical Veterinary Science, University of Bristol, Langford House, Langford, Bristol BS18 7DU Dr Meredith's present address is Pig Disease Information Centre, 4 New Close Farm Business Park, Bar Road, Lolworth, Cambridgeshire CB3 8DS The causes and timing of piglet mortality were studied in different farrowing systems. In the first experiment 198 litters were recorded in three systems, two of which allowed the sows to move freely, and the third restricted them in conventional crates. More piglets were weaned from the conventional crates than from the open systems and they grew more quickly. More than half the liveborn mortality occurred during the first four days after parturition. In the open systems, 17 per cent and 14 per cent of the piglets born alive were crushed, compared with only 8 per cent in the crates. In the second experiment, 29 sows and litters were studied in detail in a communal pen system during the first seven days of lactation. Three-quarters of the liveborn mortality was due to crushing. The total number of piglets dying per litter, including stillbirths, was significantly associated with the total litter size and the sow's parity. The percentage livebom mortality was significantly associated with the parity and body length of the sows and with the within-litter variation in the birth weight of the piglets. Individual birth weight was closely associated with percentage survival. Only 28 per cent of piglets weighing less than 1-1 kg at birth survived to seven days. WELFARE concerns in pig farming have centred on practices in which the adult sow is closely confined. Sow stalls and teth- ers are now banned in the UK and the farrowing crate has been criticised because it confines the sow before parturition and throughout lactation. The farrowing crate was originally introduced to make it easier to manage sows, to allow higher stocking densities and to reduce piglet mortality (Fraser and Broom 1990). It can be argued that crates have fulfilled these objectives, but recent research has indicated that they may put sows under stress (Jarvis and others 1997). Alternative systems, in which the sow can move freely, are now being promoted. However, these alternatives have made management more difficult, require more space and often result in higher piglet mortality than farrowing crates (Edwards and Fraser 1997). Outdoor farrowing systems, in which the sows are not confined, appear to have levels of preweaning mortality comparable to those in farrowing crates, 10-8 per cent and 11-3 per cent for outdoors and indoors, respectively (Meat and Livestock Commission [MLC] 1998). This suggests that a successful, unconfined, indoor far- rowing system maybe achievable. However, it is probable that more piglets are born alive in farrowing arks than are recorded by farmers (Edwards and others 1994), because of inaccuracies resulting from their inaccessibility. At present in the UK, 7-1 per cent of piglets are lost through stillbirths (MLC 1998) and a further I11 per cent of liveborn piglets die before weaning (MLC 1998). These losses have remained relatively unchanged for many years. It is therefore necessary to develop farrowing systems specifically designed for modern sows, which are large in mature body size and often produce large, variable litters with a high proportion of small, weak piglets (Herpin and others 1996, Daza and others 1999). The farrowing systems under development at ADAS Terrington were originally designed to utilise efficiently the space available in pens from which crates had been removed. The intention was to give sows an environment which would allow them to maintain their natural behaviour around the time of parturition and throughout lactation, while main- taining the same number of farrowing places as the crate sys- tem that was being replaced. In order for specific problems within such alternative systems to be identified and tackled, the causes and timing of piglet deaths need to be assessed and compared with those recorded in indoor crate systems (English and Wilkinson 1982, English and Morrison 1984, Edwards and others 1986) and outdoor farrowing systems (Edwards and others 1994). This paper describes the results of two experiments to investigate the causes and timing of piglet deaths in two different experimental group-farrowing systems and in a commercial crate system. MATERIALS AND METHODS Experiment 1 Animals and management One hundred and ninety-eight Large White x Landrace sows (Pic) were balanced for parity and assigned randomly to one of three farrowing treatments housed in three adjoining rooms of identical dimensions (38 m2) within the same building. The first, a communal farrowing pen system (Pen) con- sisted of five individual pens (2-75 m x 1-50 m) each with a triangular, thermostatically-controlled creep in one corner and a farrowing rail around the perimeter, 20 cm out from the wall and 20 cm above the floor. A feed trough, piglet drinker and sow drinker were situated in the pen. From the pen, the sow had access to a 2-25 m wide communal passageway and an outdoor dunging area (15 m2). The piglets were contained in the pen up to the age of about seven to 10 days by a bar- rier 0-3 m high. There was an electronic sow feeder station at one end of the communal passageway. The pen was bedded with chopped straw. The second, a communal farrowing crate system (Free Crate) consisted of five commercial farrowing crates (2-25 m x 0-60 m) within individual pens (2-25 m x 1*50 m), with a thermostatically-controlled creep along one side. On the day after farrowing, piglet containment barriers 0 3 m high replaced the front and back components of the crates. The sow was thus able to walk through the crate and gain access to front and rear communal passageways, both 1-4 m wide, and an outdoor dunging area (15 im2), while the piglets were contained within the pen up to the age of about seven to 10 days. There was an electronic sow feeder station at one end of the front passageway. The pen was bedded with chopped straw. The Veterinary Record, August 19, 2000 209