Hazard Analysis and Critical Control Points System for a Bull Semen Production Centre

Bull semen production centres (SPC) generally present satisfactory quality control for sperm processing, but non‐standardized hygiene procedures. This study describes a Hazard Analysis and Critical Control Points (HACCP) system developed for bull SPC and subsequently implemented in a commercial SPC. After the identification of hazards at each step of semen processing and the determination of their risk and severity, monitoring and corrective procedures were designed to assess the system's efficiency. The HACCP system identified six microbiological hazards, 10 physical hazards, four chemical hazards and three critical control points. After the establishment of Good Processing Practices, Standard Operating Procedures and Standard Sanitizing Operating Procedures, the system was validated through an audit, to identify eventual failures and to define measures to correct them.     

The Importance of Including the pH Dependence of Sulfate Adsorption in a Dynamic Soil Chemistry Model

Sulfate adsorption is an important process when modeling the dynamics of recovery from acidification. In the dynamic soil chemistry model SAFE sulfate adsorption is modeled by a pH and sulfate concentration dependent isotherm. This isotherm has been parameterized by fitting it to data from batch experiments on soil samples using multiple linear regression. The soil samples were from the B-horizon from three sites, two from the Lake Gårdsjön area in south-west Sweden and one from southern Poland. The pH dependency of sulfate adsorption is important. The batch experiments show that the adsorbed amount, at a specific sulfate concentration, increases considerably with decreasing pH. This implies that the adsorbed pool of anthropogenic sulfate in soils may remain fairly high during the recovery phase. Although a decrease of sulfate concentration is commonly seen, the modeled pH increase is often slow, and thus delays in the modeled desorption of anthropogenic sulfate can be expected.