Nutritional, technological and managerial parameters for precision feeding to enhance feed nutrient utilization and productivity in different dairy cattle production systems.

Increased future demand of animal products as well as competition between food, feed and fuel, require efficient utilization of feed resources to strengthen environmental, economic and social sustainability of livestock systems. The objective of this review is to summarize current knowledge on precision feeding (PF) and the relevance of PF approaches in dairy cattle production systems in developing countries. The concept of PF aims at achieving balanced nutrition (matching animal requirements with nutrient supply, preferably from locally available feed resources) to improve animal productivity and to reduce both the cost of production and environmental pollution. In addition to the supply of proper amounts of nutrients to the dairy cow using various methodologies and tools, approaches that enhance overall nutrient digestion and availability to the animal are also discussed as an integral part of PF. These approaches involve improved analyses of feed ingredients, nutrient requirement determination, formulation of a balanced ration, individual feeding, optimization of rumen and post rumen digestion, and optimization of metabolism of absorbed amino acids and other nutrients. Based on identified and analysed PF approaches, processing and treatment of forage, including conservation through ensiling, is promising to improve feed intake and productivity of the cow and to reduce excretion of environmental pollutants per unit milk. Experiments with rumen protected nutrients for both fat and protein gave a wide range of results. Inconsistent effects of the use of enzymes such as cellulases and xylanases on feed efficiency have been observed. Plant extracts need more research to get tangible results but have a broad scale of potential (indirect) advantages on production and health. Similarly more research is needed for probiotics and acidifiers, which have shown inconsistent results. Medicinal or hormonal approaches have proven to be effective in animal performance and feed efficiency. Feeding concepts, such as ration balancing programmes or the use of feed blocks, resulted in improved feed efficiency and substantially increased farmer income. In view of large variation in forage quality, rapid determination of nutrient composition of forage on site is indispensable in PF of dairy cattle. The relevance of application of the elaborate approaches for intensive, mixed crop-livestock, mixed extensive and extensive systems have been discussed. The focus of PF in developing countries should be on using feed resources that do not compete with human food, and in amounts that meet the nutrient requirements for production from the targeted animal. Policy and institutional building options are needed to realize the potential of PF for sustainable dairy production systems.