Hyun-Su Hwang

Effects of Mixing on the Aggressive Behavior of Commercially Housed Pigs.

In this study, we investigated the effects of mixing on the aggressive behavior of commercially housed pigs. The behavioral patterns of 36 groups of pigs (a total of 360 animals) were observed over 3 consecutive days directly after weaning (25±1.2 days of age), and 25 and 50 days later with the aid of video technology. Fight latency and total duration and frequency of fighting were significantly different among the age groups. The aggressive behaviors decreased in 75-day old pigs if compared to 25- and 50-day old animals. Moreover, dominance index (DI) was higher in 25-day old and lower in 75-day old pigs. A comparison of dominant (DI>0) and submissive (DI<0) pigs showed significant differences (p<0.05) for major aggressive behaviors in all age groups. Dominant pigs were involved in more aggressive interactions, had longer fights, and initiated more fights than submissive pigs. Post-mixing aggressive behavior was altered by previous experience of mixing. Aggressive behavior and DI are suitable methods for analyzing the effects of mixing on commercially housed growing pigs.

Molecular dynamics study of carbon nanotube oscillator on gold surface

We investigated the substrate effect of carbon nanotube (CNT) oscillators using classical molecular dynamics simulations. Double-walled CNT oscillators on {100} gold surface were considered. The nanotube–gold interactions induced the compressive deformations of the outer nanotube and affected the transitional velocity and the energy dissipation of the nanotube oscillator. When the inner nanotube was extruded from the outer nanotube, the central regions of the outer nanotube were compressed by the nanotube–gold interactions and then, these compressive forces pushed out the inner nanotube and finally, the transitional velocity of the inner nanotube was slightly increased at the edges regions. Since the energy dissipation of the nanotube oscillator on gold surface was higher than that in vapor, the decrease of the transitional velocity for the nanotube oscillator on gold surface was greater than that for the nanotube oscillator in vapor.

Behavioral Characteristics of Weaned Piglets Mixed in Different Groups.

With regard to animal welfare concerns, behavioral information of weaned and mixed piglets is great interest in swine production. The aim of this study was to demonstrate the change in behavior of weaned piglets over time in two different groups (littermates and piglets from different litters) after mixing. Two weaned groups of piglets (72 individuals in all) housed either with littermates or with foreign piglets (6 individuals in 1.8 m×1.4 m pens, 28°C±1°C temperature) were observed with the aid of video technology for 9 consecutive hours on days 1, 2, and 3 after mixing. The behaviors of the weaned piglets in the control and treatment groups were significantly different among the days after mixing. Piglets were, however, more active and aggressive in the groups with foreign piglets. This study reveals a lower level of agonistic behavior in groups of piglets that came from the same litter.

Ecological factors influencing the winter abundance of mammals in temperate forest

Abstract. We examined the ecological factors influencing winter abundance of mammals in the natural deciduous forest and the Japanese larch, Larix leptolepis, plantation in Mount Maehwa, Hongcheon, South Korea. We counted the tracks of five mammal species — the Korean hare, Lepus coreanus; the raccoon dog, Nyctereutes procyonoides; the Siberian weasel, Mustela sibirica; the water deer, Hydropotes inermis and the wild boar, Sus scrofa — in the snow from November 2013 to February 2014. We showed that the mean basal area, canopy cover and shrub cover were significantly higher in the Japanese larch plantation than in the natural deciduous forest. The winter abundances of Korean hares, raccoon dogs and water deer were higher in the Japanese larch plantation than in the natural deciduous forest. The results of stepwise analysis revealed that the winter abundances of four species were significantly correlated with ≥ 1 of the habitat variables. The winter abundances of Korean hares, water deer and wild boars were significantly correlated with shrub cover. The winter abundances of Korean hares, raccoon dogs and wild boars were significantly correlated with fallen logs; and the winter abundance of water deer was significantly correlated with canopy cover. For all of the investigated species, the preferred winter habitat was the Japanese larch plantation, with dense shrub cover and high number of fallen logs. Our results indicate that for planning conservation and forest management strategies for mammal species, the preferred forest habitat variables must be taken into consideration.

Influence of tree thinning on the abundance of mammals in a Japanese larch Larix kaempferi plantation

ABSTRACT We examined the influence of tree thinning on the abundance of mammals in a Japanese larch Larix kaempferi plantation in Mt Gariwang, Pyeongchang, South Korea. In 2014 and 2015, from April to October, we recorded the presence of tracks as a proxy for abundance, for the following seven mammalian species: Korean hare Lepus coreanus, raccoon dog Nyctereutes procyonoides, Siberian weasel Mustela sibirica, Eurasian badger Meles meles, water deer Hydropotes inermis, roe deer Capreolus pygargus, and wild boar Sus scrofa. We also assessed how the intensity of tree thinning affected vegetation cover; there were significant differences in number of standing trees, basal area, coverage of vegetation layers, and number and volume of downed trees among the control, moderately thinned, and intensively thinned stands. We found significant differences in the abundance of tracks among the stands for three mammal species. In four mammal species, the abundance of track was significantly correlated with volume of downed trees, coverage of ground vegetation, number of downed trees, and number of standing trees, according to stepwise analysis. The presence and abundance of mammals is linked to habitat variables and forest managers should consider how habitat modifications will affect wildlife.

Effect of begging call playbacks on growth of great tit, Parus major, nestlings

This study was conducted to clarify the effects of begging call playbacks on the growth of great tit, Parus major, nestlings in artificial nest boxes. The mean body mass of nestlings significantly differed between the control (60 dB playback intensity), playback 1 (80 dB), and playback 2 (100 dB) groups. However, mean tarsus length was not different based on treatment. The daily body mass and tarsus length gain of nestlings in playback 2 were higher than in the control and playback 1 groups in this study. Further long-term research is needed to understand the relationship between begging behavior of nestlings and parental care in the great tit.

Atmospheric factors influence body and egg of great tits Parus major

ABSTRACT This study was conducted to investigate the influence of atmospheric factors on the body and egg of great tits (Parus major), which were bred in artificial nest boxes from March to July of 2012 and 2013. The mean temperature and relative humidity were significantly higher in the spring season of 2012 than in 2013. Body masses of incubating parent birds differed between both years. Eggs which were laid in 2012 were larger and heavier than those of 2013. Hue and saturation values for background and spot colors were significantly different between 2012 and 2013. In 2012, there were warmer and wetter atmospheric conditions, which may influence vegetation and food availability for the birds. The large, heavy, and less vividly-colored eggs were laid in 2012 by parents with good body condition. Results showed that spring atmospheric factors influenced both body and egg of great tits. Further studies on the relationships between atmosphere, vegetation, and food availability of the birds are needed.

Behaviors and body weight of suckling piglets in different social environments

Objective This study was conducted to characterize the behaviors and the body weight of suckling piglets in different social environments. Methods Two groups of sows and suckling piglets housed either in individual farrowing crates in separate pens (1.8×2.4 m, the control group) or in groups of three sows with their piglets in farrowing crates in a large common enclosure (5.4×2.2 m, the treatment group) were observed with the aid of video technology for 9 consecutive hours on days 1, 2, and 3, after mixing. Results Suckling, agonistic, and elimination behaviors of suckling piglets were significantly higher in the control group than in the treatment group. Inactive behavior was higher in the treatment group than in the control group. Most of the effects of the social environment on the suckling piglets seem to be the result of large reductions in behaviors and body weight for piglets switching from high activity to low activity. Moreover, suckling behavior and birth body weight were highly correlated with body weight at the end of the test. Conclusion The social environment that resulted from mixing, thus, had significant effects on the behavior and body weight of suckling piglets, and behavioral characteristics, therefore, should be considered when making improvements to the husbandry and care methods used in swine production.

Characteristics of mammal abundance relative to habitat variables in temperate forests

This study was conducted to examine the characteristics of mammal abundance that are related to habitat variables in natural deciduous forest and Japanese larch (Larix leptolepis) plantation in the national forest of Mt. Gariwang, Pyeongchang, Korea. Habitat variables differed between forest types. We counted the mammal trails of Korean hares (Lepus coreanus), raccoon dogs (Nyctereutes procyonoides), Siberian weasels (Mustela sibirica), Eurasian badgers (Meles meles), water deer (Hydropotes inermis) and wild boars (Sus scrofa) during the study period. Eurasian badgers, water deer, and wild boars exhibited one or two significant correlations with coverage of understory, downed trees, and coverage of overstory, as determined using a stepwise approach. Habitat variables could be used as predictors of mammal abundance, and thus forest managers should consider such variables in mammal conservation and management activities.

Bill color characteristics and body mass of the great tit (Parus major) nestling

This study was conducted to examine the bill color and body mass of great tit (Parus major) nestlings in artificial nest boxes. In this study, the nestlings with yellow bills had a higher body mass on the second and eighth day after hatching. Moreover, the brightness values of the color of the bill on the eighth day after hatching were negatively correlated with the body mass of the chicks. Our experiment shows that the color of the bill of the nestling could accurately signal the quality of the chick. Moreover, carotenoid-based colors play an important role in avian communication. Study of carotenoid-based colors in the great tit would be required in the future.