There are so many feed stuffs that sometimes its difficult to evaluate them. Quality control can be done calculating the nutrient value of the ingredient.We can do qualitative analysis and quartitative also. Qualitative will include organoleptic characteristics like, color, odour, taste, texture and particle size and shape ( with a stereoscopic magnifying glass). Actually you can recognize ingredients by this method and also its proportions. This will lead to identify adulterations. Its cheap and efficient. We can do that by using chemical methods that are standarized, like Acid Detergent Fiber, Neutral Detergent Fiber. Also we calculate Crude Protein, Crude fiber,Ether Extract ( for lipids), biuret for protein, ashes, non proteic nitrogen and so on.We can identify anti nutritional factors, extrinsec like pesticides, mycotoxines, weeds, insecticides, herbicides fungicides.Or intrinsec like allergenics, glucosinolates ( from rape seeds ), saponines, tanines, urea and much more. For this analysis the most important thing is taking a good random sample. If the feedstuff is fibrous we can use quadrants ( in pasture for example) and a sampler in a truck of grain. Also protein quality and aminoacids are important to evaluate if they come from a vegetal or animal source. An electronic microscope will allow us to identify ingredients by tissue aspect. Also there is technology. We can use Near Infra Red Spectroscopy that is based on molecular overtone and combination of vibrations.