Use of a crush-reducing device to decrease crushing of suckling piglets by sows.
Weanling pigs tend to avoid wind, and suckling piglets are thought to be more sensitive to wind than weanlings, owing to their thinner s.c. fat layer. We developed a crush-reducing device based on the anticipated behavior of suckling piglets toward wind and evaluated the performance of the device through field testing. The crush-reducing device consisted of six photo sensors, a controller, six solenoid valves, and an air compressor. In this study, 206 sows and their suckling piglets (Landrace xYorkshire) were investigated to ascertain the individual effects of several factors. Some of the newborn piglets were cross-fostered before the crush-reducing device was implemented. Litter weights were measured on d 0 and 4 to determine the influence of the crush-reducing device on the weights of suckling piglets. The crushing of suckling piglets by sows was affected by season (P < 0.01) and litter size (P < 0.05), but not by the parity of the sows; however, the number of crushed piglets per litter was less (P < 0.01) in the crush-reducing device group (0.05 +/- 0.02 crushed piglets/litter) than in the control group (0.23 +/- 0.04 crushed piglets/litter), regardless of litter size or season. The BW gain of suckling piglets did not differ between the control and the crush-reducing device groups. Based on these results, the crush-reducing device is expected to decrease the number of crushed piglets per litter without influencing the BW gain of suckling piglets, thereby greatly contributing to the productivity of pig breeders.
The effects of air velocity and temperature on the behaviour and growth of pigs
The effects of different combinations of air velocities and temperatures on growing and finishing pigs were studied in controlled climates. Behavioural studies were made, and pen and animal hygiene, growth, feed conversion and tail-biting were recoreded. Experiments were so arranged that pigs in some pens were able to choose between two or three different thermal environments. With −5°C outside and 15–18°C inside, higher air velocities caused greater body contact between the lying animals, a smaller incidence of animals lying in the dunging area, good pen hygiene, lower growth rates and a tendency to increased tail-biting. During summer, low air velocity combined with high inside temperature caused little body contact between lying animals, a greater incidence of animals lying in the dunging area, bad pen hygiene, lower growth rates and a tendency to increased tail-biting. A relationship between the animal reactions and a chill factor (a direct expression for cooling by convection) was developed. The optimum chill factor is between 60 and 80 W/m2. For a 70 kg pig, if the inside temperature is 16°C, the air velocity should be in the range 0·15–0·28 m/s. At an inside temperature of 28°C, the air velocity should be in the range 0·74–1·31 m/s. It is shown that the direction of the incoming air significantly influences pen hygiene during summer conditions.
The relation of food quantity to rumination behavior.
Preliminary work suggested that the quantity of food ingested by retarded individuals who usually ruminated following meals was related to the frequency and duration of ruminating responses. This possible relation was experimentally examined by systematically varying food quantity from regular portions to satiation levels for three retarded individuals who exhibited high levels of ruminating. A clear functional relation of food quantity to ruminating emerged, with satiation procedures producing rapid and large decreases in the relatively high frequencies and durations of ruminating characteristic of baseline food quantity conditions.