The law of diminishing returns (LDR) has been applied in numerous fields, including livestock production, to determine the optimum level of a certain variable input. This integrated review tries to synthesize and discuss the appropriateness of LDR in describing profiles of livestock yields and grass regrowth after each cutting in response to to increased levels of a variable production input, as well as to analyse and generalize major applications of the law in determining the optimum levels for a number of important variables such as slaughtering age, feeding level, nutrient contents in the ration, grass cutting interval, herd size, stocking density, etc. in order to balance economic profit, social justice, environmental protection, and animal welfare, thus ensuring sustainable development of livestock production.