It has been pointed out that rubber gloves have an adverse effect on the properties of porcine sperm ; nevertheless, rubber gloves are still often used when collecting porcine semen. Rubber products such as gloves are made up of many components, and these different components may have different effects on sperm viability. In this study, we compared the effects of different disposable glove materials, including those made of rubber, on the quality of spermatozoa obtained from standard pig varieties in Japan. In Experiment 1, the semen was co-cultured with pieces of natural rubber, nitrile rubber, nitrile rubber without vulcanization accelerator, or polyethylene gloves. Sperm motility was significantly reduced in cultures with natural rubber, nitrile rubber, and nitrile rubber without vulcanization accelerator. By contrast, semen quality in cultures with polyethylene did not differ from that of control cultures, which did not contain any glove material. The effects of co-culture with glove material on acrosome integrity were less than those on sperm motility, although these effects increased with the time of co-culture in culture with nitrile rubber and nitrile rubber without vulcanization accelerator. In Experiment 2, nitrile rubber was thoroughly washed with water or soap before co-culturing with semen. Washing reduced the harmful effects on sperm, but did not restore motility and normal acrosome levels to those in control cultures without glove material. In Experiment 3, semen was co-cultured with four types of polyethylene gloves. Motility and acrosomal normality were slightly reduced in coculture with one type of polyethylene glove, but the remaining three types showed no difference from controls. Our results indicate that gloves composed of natural rubber or nitrile rubber, including those without vulcanization accelerator, have a significantly deleterious effect on the characteristics of pig semen, particularly motility ; this harmful effect was not obviated sufficiently by washing the gloves. On the other hand, most polyethylene gloves have been found to be very safe. Therefore, when collecting and processing semen, the use of rubber products should be avoided and other materials such as polyethylene should be used.

A livestock manure treatment is one of the sources of greenhouse gas emissions (GHG), CO₂, CH₄, and N₂O emissions through manure handling. The amount of these emissions differs from the manure handling type and the quantity and quality of wastewater and solids. The solid-liquid separator would increase and decrease GHG emissions due to changes in the material flow in manure handling systems. For example, the equipment reduces the BOD (biochemical oxygen demands) volumetric loading during the aeration process of purification, changing the quantity and quality of wastewater. Therefore, we evaluated four pig manure treatment systems (scenarios of a feces-and-urine separation system, a feces-and-urine mixture system, a sewage-dewatering system, and a sludge-dewatering system) to clarify GHG emissions from livestock manure treatment systems, including the effects of the solid-liquid separator, using the LCA method.

We assumed four manure treatment system scenarios based on 2,000 fattening pig farm scales. The system boundary was the processes of manure discharged from the livestock barn to composting and purification, and the evaluation stage was considered equipment construction and operation. The evaluated GHG emission was carbon dioxide, methane, and nitrogen dioxide. A comparison of the feces-and-urine mixture system, the sewage-dewatering system, and the sludge-dewatering system revealed the following. The sewage-dewatering system, separating sewage and sludge into solids and liquids, reduced GHG emissions by approximately 26% compared to the feces-and-urine mixture system. On the other hand, the sludge-dewatering system, which separates only sludge from solid to liquid, generated about 17% more GHG than the feces-and-urine mixture system.