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 liveborn 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.

No abstract

No abstract

The scientific assessment of farm animal welfare requires an amalgam of different measures of both physiology and behaviour. Behavioural measures are relatively easy to obtain but non-invasive measures of internal physiology are somewhat harder to achieve. An increase in the use of applied physiology in training regimes of human athletes, has led to an improved technology of heart rate monitors, making the measurement of heart rates painless and easy to record.The objective of this experiment was to use a human heart rate monitor to investigate differences in heart rate response at feeding between sows housed in three different dry sow housing conditions. Schouten et al (1991) have demonstrated differences in heart rate response at feeding between loose-housed and tethered sows. In the study reported here, stall-housed sows were compared with sows housed in small groups and sows housed in a large group with an Electronic Feeder System (EFS).

A major problem reported by many commercial producers keeping sows in group housing systems, is that of inter-sow aggression and bullying, due to the establishment and maintenance of a social hierarchy. Even in stalls and tethers, inter-neighbour aggression can be high but the physical consequences for the sow receiving the aggression are negligible, due to the lack of opportunity for physical contact. In a group situation, an inability to prevent attack by another sow can itself lead to poor welfare, in addition to any effects of injury or pain caused by the attack. A sow's ability to control its social environment can not only affect its access to resources (Edwards et al., 1993), but also its physiological state and productivity (Mendl et al., 1992).The aim of this experiment was to determine the effects that different intensities and degrees of success of agonistic social interaction have on the heart rate of sows, which can be a useful measure of the emotional response of an individual to short-term problems such as social challenge.