Systems analysis applied to animal husbandry

Abstract

Animal itself and the industry are complicated systems, because they are composed of many segments and components. In this study, systems-analysis techniques were applied to the following three subjects of animal husbandry. (1) As livestock production in Japan has become more intensive, livestock wastes tend to cause serious environmental problems. Nitrogen (N), phosphorus (P), and potassium (K) flows in livestock farms were estimated to obtain fundamental data for solving these problems. Simulation of N, P, and K flow models in dairy farms showed that the higher the milk production performance of cow is, the lower the N surplus per kg milk is. This result indicates that enhancement of milk production contributes to the reduction of environmental loss of nutrients. Life cycle assessment (LCA) was used to assess all the environmental impacts on livestock management, feed production, applied chemical fertilizer production, and manure management. Imported feed, such as corn and barley, showed higher global warming impact and acidification impact than self-supplied feed and by-product feed. (2) Three types of production models were characterized and compared; growth curve models, ad libitum feeding and growth models, and system simulation models. The growth curve models are the most simple ones which represent a relationship between age and weight and the animal is considered a black box with only output. The ad libitum feeding and growth models involve feed intake as well as weight and the animal is considered a black box with input and output. In the system simulation models, the animal is regarded as a white box of which internal relationships are known. In general, system simulation models have been developed based on popular energy systems and some of them permit us to estimate body and carcass composition and extend to bio-economic models by taking account economic variables. In this review, the historical perspective of the modeling effort and application of a bio-economic model for beef cattle production systems were illustrated. (3) It is important to improve animal performance of total population itself because of long generation interval, high value of an animal and low reproducibility. Optimization of a breeding system including performance test, selection method, production system and so on is essential. Here, the rate of genetic gain of the Japanese Brown Cattle population were compared between the station system and the field system for progeny test. It was the field system that was effective for improvement of carcass traits which had been considered to be difficult. A more efficient breeding system for the beef cattle has been perusing to optimize another factors. As described here, systems analysis is an effective tool to resolve complicated problems in animal industry and will play an important role in the future more and more.