Influence And Regulation Of Environment In Lying Areas For Small Group-housing Sows

The housing system for sows in individual stall has significant effect on improving the stocking density and industrialized management, but it may result in increasing stereotypic behavior and decreasing their immunocompetencedue to the restrictions of activities and the expression of normal behavior of sows. At the same time, the high airtight and heat preservation of piggery construction are desired for the housing system. Otherwise it will cause death and culling rate increased, reproductive performance decreased and so on. Therefore, in recent years, people are paying more and more attention to activity space and animal welfare of sow.The systems for group-housing sows, which can meet the biological characteristics and behavior of sows, are getting more and more attention in the developed regions like the EU. The pen of group housed sows is usually divided into feeding area, lying area, active area and discharge area to achieve clean production of pig. In this study, a new system for small group-housing sows combining feeding area with lying area is explored, and a kind of swine bed free to go in and out is developed, which can be used not only as the feeding arrangements when sows take food, but also lying aera for sow. In addition, it is possible for sows to have serious stress response due to the extreme temperature of winter and summer and cold air caused by the sudden drop of temperature in spring and autumn in China. However, it is not easy to achieve the insulation performance in most of the piggery, for the cost is high with respect to controlling the ambient temperature of the whole house and energy consumption. Realizing the fact that pregnant sows spend approximately80%of the whole day lying, the optimization of environment and the problem of temperature control in lying area have been studied particularly in the thesis. The structure of the swine bed was converted on the basis of a lot of existing research. Then the local temperature regulation of swine bed in lying area and the effect of swine bed on the behavior of sows were researched under the condition of high temperature in summer and low temperature in winter. Impact of unit width of swine bed and social hierarchy on behavior of group-housed pregnant sows were also studied. Moreover, a kind of door with automatic locks, which was free access to and used to separate pigs, was designed and developed. The insulation effect of semi-open swine bed and its effect on the behavior of pregnant sows were also evaluated. The main conclusions of this study are summarized as follows:1. Condensation water form on the surface of pipes when swine bed is running groundwater under high temperature environment in summer. When the pipe was tilted above20°, condensation water of surface of the pipe dropped at its bottom rather than the surface of the pipe. Therefore, it can resolve the problem that condensation water of surface of the pipe dropped the sows’lying area when upper end of pipe tilted angle above20°, and the lower part of pipe was upright.2. Cooling of swine bed pumped in groundwater may reduce the heat stress and improve reproduction performance of sows in summer. when the ambient temperature of piggery and inlet water temperature of swine bed were35℃and21.2℃, respectively, and water flow reached0.72m3/h, the black globe temperature on the bottom of swine bed was4.7℃lower than that outside the swine bed. Correlation between cooling effect of swine bed and temperature difference of internal piggery and inlet water, as well as distance from the end of inlet water.is linear The number of sows lying under the swine bed increased with the increasing of the environmental temperatures. When the ambient temperatures was above31℃,75%of sows lay under the bed swine. Cooling of swine bed could decrease significantly the skin temperature and respiratory rate for heat-stress sows and increase the numbers of piglets born alive per litter, litter weight of piglets born, reduce number of stillborn piglets per litter.3. Both the door-curtain at two ends of swine bed and a kind of semi-open swine bed could increase local temperature in lying area for sows in winter. The results show temperatures in unit of swine bed in the experimental group were3.2℃and6.9℃higher than that of control group and indoor respectively. Compared with the sows of control group, the sows of experimental group spent more significant lying time, but were lower the frequency of drinking and biting chain every day.4. Unit width of swine bed and social hierarchy affected lying and feeding behavior of group-housed sows. The total lying time each sow spent in the600mm width unit was significantly less than that in the800mm. The aggression number happened in the700mm or800mm width unit were significantly more than those from the600mm width unit. The replacement number of feeding position increased progressively with increasing the unit width of swine bed, and had significant difference among different width units. Compared with submissive sows, the number of attack and replacement position initiated by dominant and subordinate sows were significant more. However, the number was significant less in feeding.