Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

Objectives : This research examined the effect of urbanization on environmental justice in Rwanda from 1999 to 2019. Specifically, the research sought to document changes in land use and land cover in the study region in order to analyze the environmental consequences of urban growth in Rwanda.Methods : Land use/land cover patterns were identified and modelled using remotely sensed data.Results and Discussion : The findings revealed that in the majority of cases, economic development influenced land use change in various aspects, both in terms of area and intensity, which replaced agricultural land with human settlements. For example Nyagatare city, built-up areas have expanded by 15 to 20%, while forests, vegetation, and waterbodies have decreased by 49%. It has been noted that urbanization is out of step with the natural urban environment, resulting in soil erosion, violent winds, flooding, and landslides, all of which are linked to environmental injustice. Also, settlement destruction, flooding, infrastructure damage, loss of natural habitat, and agricultural loss were all linked to urban expansion, particularly uncontrolled settlements in metropolitan contexts, with 64 people killed and 178 injured in just five years.Conclusion : Therefore, this shows that there are consequences of biodiversity losses which affect land use and land cover. To overcome, the research suggests current households located in high-risk zones be moved to the convenient zones and the government policy to focus on family planning, encouraging the flexibility of land use, crop production, and farming systems based on agroecosystem models, and strengthening the greening city strategy by raising public understanding on environmental issues.

The rollover tendency of upland farm machinery needs to be carefully considered because upland crop fields are typically irregular, and accidents frequently result in injuries and even death to the operators. In this study, the rollover characteristics of an underdeveloped 12 kW automatic onion transplanter were determined theoretically and evaluated through simulation and validation tests considering the mounting position of the transplanting unit and load conditions. The center of gravity (CG) coordinates for different mass distributions, and static and dynamic rollover angles were calculated theoretically. Simulation and validation tests were conducted to assess the static rollover angle under different mounting positions of the transplanting unit and load conditions of the onion transplanter. The dynamic rollover tendency was evaluated by operating the onion transplanter on different surfaces and at different speeds. According to the physical properties and mass of the onion transplanter, the theoretical rollover angle was 34.5°, and the coordinates of the CG gradually moved back to the rear wheel axle after attaching the transplanting part and under upward riding conditions. The average simulated rollover angle was 43.9°. A turning difference of 4.5° was observed between the right and left sides, where a 3° angle difference occurred due to the load variation. During the dynamic stability test, angle variations of 2~4° and 3~6° were recorded for both high and low driving speeds in the vehicle platform and transplanting unit, respectively. The overturning angles also satisfied the ISO standard. This study provides helpful information for ensuring the safety of upland crop machinery operating under rough and sloped field conditions.

Widespread use of plastic seedling pots has been attributed to their light weight and durable characteristics. However, these pots have limitations in facilitating efficient root establishment. Recent studies indicate that biodegradable seedling pots not only enhance seedling resilience but are also environmentally sustainable through natural decomposition. This study presents a kinematic analysis of a cabbage transplanting mechanism specifically under development for biodegradable seedling pots, focusing on position, velocity, acceleration, and power. The optimization of link combinations within the transplanting mechanism was analyzed to enhance the transplantation process, focusing on achieving precise depth and spacing for potted seedlings. A kinematic model of the mechanism was developed and simulated using commercial mechanical design and simulation software, followed by validation through performance tests. The proposed transplanter comprised a four-bar-linkage mechanism consisting of a driving link, a driven link, a connecting link, and a guide bar. Simulation trials were conducted by varying the main arm link length while keeping machine forward speed and mechanism driving speed fixed. Results indicated that the optimal mechanism parameters included a driving link of 50 mm, a connecting arm of 120 mm, a guide bar of 120 mm, and an end-effector link of 220 mm. A dibbling hopper length of 153 mm was identified as the most effective for operation. With these recommended link lengths, validated velocities of the end hopper in the ‘X’ and ‘Y’ directions were 284 mm/s and 1379 mm/s, respectively, while corresponding accelerations were measured at 1241 mm/s² and 8664 mm/s². The driving power requirement was calculated to be 17.4 W. These findings suggest that the developed mechanism provides effective planting performance, evidenced by a high degree of seedling uprightness and minimal soil disturbance. This study supports the use of biodegradable pots in mechanized transplanting as a viable alternative to conventional plastic pots, with potential benefits for both agricultural efficiency and environmental sustainability.

Aim of study: To determine the optimal working speed of a gear-driven rotary planting mechanism for a self-propelled riding-type onion transplanter in order to choose an adequate forward speed for effective onion (Allium cepa L.) seedling planting. Area of study: Daejeon, Korea. Material and methods: The gear-driven rotary planting mechanism was composed of six planting hoppers that received free-falling onion seedlings through the supply mechanism and deposited them into the soil. To determine the optimal working speed for accurate transplantation of the seedlings, mathematical working trajectory modelling of the planting mechanism, virtual simulations, and validation field experiments were carried out. Main results: According to the model simulation, a forward speed of 0.15 m s-1 of the transplanter and a rotating speed of 60 rpm of the planting mechanism were favourable for seedling uprightness and minimum mulch film damage. For the proposed transplanting mechanism, the free-falling distance was calculated as 0.08 m, and the accuracy for the seedling deposition into the hopper was demonstrated as 97.16% through the validation test. From the field tests, a forward speed of 0.15 m s-1 combined with a transplanting frequency of 60 seedlings min-1 was found to be optimum for obtaining a high seedling uprightness (90o), a low misplant rate (7.66%), a low damage area on mulch film, and low power consumption (36.53 W). Research highlights: The findings of this research might be helpful in improving the design of the onion transplanting mechanism and accelerating the automation process for seedling transplantation.