Shape of lactation curve, with special reference to feeding strategy, health, fertility, and economic outcome in dairy

Summary The total milk production during a full lactation is determined by the peak and the shape of the lactation curve. A primarily analysis of the mean lactation curves for different large herds under Norwegian conditions revealed a large and substant ial differences from one herd to another. Many of the production diseases occur at the start of the lactation. The shape of these curves is mainly managed by different feeding strategies, throughout the very last part of previous lactation, dry period, bo dy condition score, and the intensity of feeding during the first part of lactation. The shape of the lactation curve will also have impact on fertility performance and meat production as well as meat quality produced from dairy cattle and thus economics in the production. The main objective of this project is to identity the optimal lactation curve in relation to feeding strategies in early lactation, health, fertility and financial return in dairy farms. By applying this knowledge we expect a decrease the disease incidence, and thus reduce the use of antibiotics, as well as the feeding costs in the dairy production. The project is divided in three parts: Part I: Identify the associations between the shape of lactation curve and production disease inci dence and economic benefit by using available data from The Norwegian Dairy Recording System Part II: A field experiment to evaluate the effect of concentrate escalation and concentrate level in the first part of lactation on milk performance, animal hea lth and fertility Part III: With knowledge from Part I and Part II do some intervention studies at Norwegian herds where identified herds with a shape of the lactation curve associated with high incidence of disease is intervened to change feeding strateg y, and thereby to change the shape of the lactation curve. Evaluate the results and see how this change influences the disease incidence and economic outcome at herd level.