Review: Advantages and limitations of dairy efficiency measures and the effects of nutrition and feeding management interventions

Economists, nutritionists, and geneticists have attempted to describe dairy cattle efficiency in simple, quantifiable terms. On-farm measures of dairy efficiency include physical feed efficiency, efficiency of nutrient usage, economic feed efficiency, total dairy enterprise efficiency, and lifetime efficiency. Each calculated measure of dairy efficiency has its own advantages and limitations. Each measure has merit for describing a segment of dairy efficiency, yet no one measure can sufficiently describe dairy efficiency or be applicable across all farms. Use of multiple dairy efficiency metrics, each with a moving target specific to the individual dairy enterprise, should be considered. Nutrition and nutrient management interventions can improve the use of dairy resources, increasing both economic and environmental sustainability. With greater DMI and milk yield, a smaller proportion of dietary nutrients are used for maintenance functions, improving productive efficiency and reducing the environmental impact of the dairy cow. Nutritional factors independent of cow genetic merit affect energetic losses in the form of feces, heat of digestion and metabolism, or methane. Improvements in nutrient retention can occur with increases in rate of digestion and decreases in rate of passage of feed ingredients. Forage and grain losses, feed ingredient options, and forage and feed ingredient targeting according to cow potential need to be considered. Consistency of delivery and consumption of the formulated ration without high feed refusal rates typically improves dairy efficiency. Cow grouping affects social behavior, cow well-being, nutrient wastage, milk yield, and expenses, with optimum strategies being farm specific.