Improving resource use efficiency and nutritional quality of grazing-based dairy production

Abstract

The dairy industry has received recent negative media coverage due to perceived poor sustainability, low animal welfare and high saturated fat content. However, evidence suggests that efficient, forage-based dairy production supports the environment and provides a nutritious product. While industrial dairy production has focused on yield as a measure of productivity, there is little research into optimising efficiency AND nutritional composition through farm management (such as breed, forage allowance, grazing strategy, etc.). Classic measures of production efficiency (kg feed/litre of milk) are not the sole priority in low-input systems, which also aim for improved health, fertility, forage conversion and milk quality. Holstein-Friesians were traditionally bred for high milk yields, which often correlate negatively with functional traits, such as fertility and health. For low-input and/or pasture-based systems, alternative breed choices are preferable, and UK dairy farmers have used several crossbreeding practices. Milk fat composition is examined alongside farm management strategies (conventional, organic, low-input and pasture-based) to identify if there is a management practice, breed and/or individual cows that are most suitable to the farming system. Consistently, farms and cows that had higher proportions of forage in their diets produced milk with a higher concentration of nutritionally beneficial fatty acids such as, omega-3 and CLA9. Despite evidence that efficient cattle have less of an impact on the environment, the metric used for efficiency in pasture-based systems is just inputs vs outputs. This thesis explores the definition of efficiency and tries to find alternative metrics that include cow health, milk quality and productivity and finds breeds and cows that perform well under these conditions. Researching the distinguishing factors of nutritional milk quality is key to sustainable production and addresses increasing media and scientific scrutiny regarding human health effects and ecological impacts of dairy products. Evidence of dairy farming systems that support the environment and provide nutritious food are essential to supporting UK dairy farmers.