Today, there are some 200 different breeds. Goats have been used by the U.S. Fish and Wildlife Service, the Bureau of Reclamation, the Bureau of Land Management, and the U.S. Forest Service. State, county and city contractors (such as the city of Seattle) have also used goats for weed and invasive species control.
Recent data has redefined the way that urologists look at PSA, and what is considered a normal PSA. Age-adjusted PSA values take into account that a 40-year-old should not have the same PSA as an 80-year-old. Accepted age-adjusted PSA rates are below 2.4 ng/ml for men under the age of 50 and 6.5 ng/ml for patients in their 70s. Other limits have been defined for varying age ranges, but there is not universal agreement about the accuracy of the age-adjusted levels.
PSA levels are measured in nanograms of PSA per milliliter of blood, or ng/mL. Men with a high PSA level are more likely to have prostate cancer than men with low levels, though there are no normal and abnormal ranges of PSA in the blood. In the past, a PSA reading of 4 ng/mL and below was considered normal.