1. A computerized method for estimating a weight of an animal, comprising: acquiring an image of an animal; comparing, by at least one computing device, the image to a plurality of models to determine a selected one of the plurality of models that optimally matches a size or shape of the animal, wherein each of the plurality of models has a known weight; adjusting, by the at least one computing device, either (i) the image relative to the selected model or (ii) the selected model relative to the image; determining, by the at least one computing device, one or more differential adjustment parameters based upon the adjustment of the image or model; and determining, by the at least one computing device, a weight of the animal by adjusting the known weight of the selected model based upon the one or more differential adjustment parameters.