Differences in feed digestibility of dairy cows

To improve feed resource efficiency and to reduce the environmental impact of dairy farming, improving feed efficiency has gained increasing interest. Recently, a breeding company (CRV, Arnhem, The Netherlands) started with routine recording of individual feed intake of cows on commercial dairy farms in The Netherlands. These measurements help to utilize individual variation between cows in feed efficiency. Research suggests that (part of) the variation between cows in feed efficiency could be explained by differences in digestibility between cows. However, inter-individual variation in feed digestibility measured at large cohorts of animals is scarce and limited knowledge is available on the relation between feed intake, feed intake pattern, feed digestibility and feed efficiency. During the last decades, improvements in nutrition together with genetic selection led to increasing milk yield and feed intake of cows. At the same time, cows’ ability to digest feed, in particular that of fiber has decreased, which is undesirable considering the role of a cow in a circular food system, where cows convert human-inedible fiber-rich diets into high quality human-edible animal products. Therefore, a high capacity to digest fibers should be (genetically) preserved, or if possible, improved. Hence, in close collaboration with a PhD candidate from the Animal Breeding and Genomics group of Wageningen University and Research, the current project aims to improve our fundamental understanding of (genetic) differences between cows in feed digestibility by collecting and analyzing fecal samples of approximately 400 cows from which individual feed intake is recorded. Special attention will be given to nitrogen, as nitrogen excretion is one of the major issues in dairy farming nowadays, especially in The Netherlands. Furthermore, possibilities to use fast and effective methods to estimate digestibility and feed efficiency via spectroscopy measurements will be explored.