The present trial verified the effects of spraying microbial agents on odor reduction in commercial pig farms of different operating sizes and barn types. Farms without microbial agent spraying and those sprayed with microbial agents at two different intervals were compared. The treatments included spraying of water alone every day or a mixture of water plus microbial agent at 24 and 72 h intervals. The experimental farms were divided according to size into 1,000-, 3,000-, and 5,000-head farms and according to barn type into gestation, farrowing, nursery, and grower-finisher farms. To compare odor concentration within each housing barn, ammonia and hydrogen sulfide gas levels were measured. The average concentrations of ammonia (p<0.01) and hydrogen sulfide (p<0.05) gas were the lowest in all types of farms sprayed with the microbial agent at a 24 h interval. In farms sprayed with the microbial agent at a 24 h interval, the decrease in ammonia concentration according to barn type was in the following order: farrowing (p<0.01) (11.0 to 1.8 ppm), nursery (p<0.05) (17.0 to 9.2 ppm), grower-finisher (15.3 to 8.8 ppm), and gestation (9.7 to 6.4 ppm) farms. Moreover, spraying the microbial agent at a 24 h interval significantly (p<0.01) decreased ammonia concentration from 19.9 to 10.4 ppm, from 11.1 to 4.1 ppm, and from 8.8 to 5.1 ppm in 5,000-, 3,000-, and 1,000-head farms, respectively. Overall, spraying microbial agents every day may be the most effective method to reduce odor in commercial pig farms.

This study was conducted to investigate the potential of toy provision for stress reduction, welfare improvement and toy preference in finishing pigs. Toy shape was expected to exert effects on stress related behaviors including fighting, bothering, and feed competition. Three different toy shapes (i.e. square, round, and oval) were given to groups of finishing pigs. A no toy control group was also included. The duration and frequency of abnormal behaviors and use time for toy preference were compared among groups. The duration and frequency of stress related behaviors was higher (p<0.01) among the non-toy-using finishing pigs on 20 minutes and 118 times than 16 minutes and 57 times of toy-using finishing pigs. Toy shape exerted no significant effects, however, toy use displayed a clear ability to reduce stress related behaviors among finishing pigs. Toy use time and shape both displayed no clear effect on the duration of stress related behaviors. These behaviors were most frequently displayed in the afternoons when the finishing pigs become most active, and were not affected by toy shape. Overall, the square shaped toy was used much longer (9.7 hours) and more frequently (566 times) in a 24 hour period by the finishing pigs (p<0.01). In conclusion, providing toys to finishing pigs reduces stress and stress related behaviors. This finding is expected to positively impact welfare and improve finishing pig productivity. Square shaped toys were most preferred by the finishing pigs, therefore adopting toys with square features is recommended.

This study was designed to investigate the effect of parity and lactation stage of sows on the behavior of nursing sows and their suckling piglets. In total 18 Yorkshire × Landrace F1 sows (range of parity: 1 to 6) and their litters (range of litter size: 10 to 14 piglets) were assigned according to the sow's parity (1-2, 3-4 and 5-6) and lactation stage (early, middle, and late). The sows were housed in farrowing crates (0.8 × 2.1 m) located in pens (2.1 × 1.75 m) with totally perforated flooring. The behaviors of the sows and their piglets were recorded over a 72-h period for each parity and lactation stage. The sows and piglets were conventionally managed. All nursing sows in both group showed lying behavior for more than 80% of the experimental period, regardless of parity and lactation stage. The behavioral frequency of sows was, in descending order, as follows: lateral lying, ventral lying, eating, standing, and sitting. The parity of sows did not affect their behavior, but the lactation stage did. Ventral lying showed decreased frequency in late stage compare to that in the early or middle stage. The lying, standing, sitting, and eating behavior of sows were not affected by their parity. Sow parity did not affect the behavior of suckling piglets, but the lactation stage did. The behavioral frequency of piglets for the whole lactation period was, in descending order, as follows: lying, suckling, and walking. The lying frequency of piglets was higher in the sow's middle lactation stage than in the early or late lactation stage. It is concluded that the sow parity did not affect the behavior of nursing sows and suckling piglets, but the lactation stage did.

The effect of inclination angle and attack angle on heat transfer enhancement of trapezoidal vortex generator was numerically investigated. The commercial package STAR-CCM+ was utilized to analyze the heat transfer and flow characteristics with various inclination and attack angle of vortex generator. The result shows that the optimum inclination angles are α =30°~40° in terms of the heat transfer and pressure drop. At more than 40° of inclination angle, the transverse vortex is dominant, so that the pressure drop is severe and the heat transfer is reduced. As the attack angle is increased, the transverse vortex is reduced, so that the pressure drop is improved. The optimum attack angle is β =30° because the heat transfer performance is maintained. However, more than 30° of attack angle, the heat transfer is decreasing.

Vortex Generators are used in heat exchanger to enhance the heat transfer of air side. 3-D numerical analysis is performed on heat transfer characteristics of a channel with trapezoidal vortex generator. We investigate the effects of vortex generators with two different inclined angles to flow direction which are forward and backward vortex generators. The thermal hydraulic performance such as Nu and pressure drop, is compared quantitatively. The results show that vortex generator enhances the heat transfer by developing boundary layers and secondary flow in the downstream. The downwash flow region corresponds to the maximum Nu, while the upwash flow region corresponds to Nu minimum. In the view of the heat transfer characteristics, FVG is better than BVG. However, when flow is turbulent as Re increases, the pressure drop for FVG is higher than that for BVG.