Invited review: overview of new traits and phenotyping strategies in dairy cattle with a focus on functional traits

Abstract

For several decades, breeding goals in dairy cattle focussed on increased milk production. However, many functional traits have negative genetic correlations with milk yield, and reductions in genetic merit for health and fitness have been observed. Herd management has been challenged to compensate for these effects and to balance fertility, udder health and metabolic diseases against increased production to maximize profit without compromising welfare. Functional traits, such as direct information on cow health, have also become more important because of growing concern about animal well-being and consumer demands for healthy and natural products. There are major concerns about the impact of drugs used in veterinary medicine on the spread of antibiotic-resistant strains of bacteria that can negatively impact human health. Sustainability and efficiency are also increasingly important because of the growing competition for high-quality, plant-based sources of energy and protein. Disruptions to global environments because of climate change may encourage yet more emphasis on these traits. To be successful, it is vital that there be a balance between the effort required for data recording and subsequent benefits. The motivation of farmers and other stakeholders involved in documentation and recording is essential to ensure good data quality. To keep labour costs reasonable, existing data sources should be used as much as possible. Examples include the use of milk composition data to provide additional information about the metabolic status or energy balance of the animals. Recent advances in the use of mid-infrared spectroscopy to measure milk have shown considerable promise, and may provide cost-effective alternative phenotypes for difficult or expensive-to-measure traits, such as feed efficiency. There are other valuable data sources in countries that have compulsory documentation of veterinary treatments and drug use. Additional sources of data outside of the farm include, for example, slaughter houses (meat composition and quality) and veterinary labs (specific pathogens, viral loads). At the farm level, many data are available from automated and semi-automated milking and management systems. Electronic devices measuring physiological status or activity parameters can be used to predict events such as oestrus, and also behavioural traits. Challenges concerning the predictive biology of indicator traits or standardization need to be solved. To develop effective selection programmes for new traits, the development of large databases is necessary so that high-reliability breeding values can be estimated. For expensive-to-record traits, extensive phenotyping in combination with genotyping of females is a possibility.

National single-step genomic method that integrates multi-national genomic information

“…If these animals are not genotyped, the value of information on ancestors diminishes very quickly with increasing distance in the pedigree. If these animals are genotyped, the increase in reliability is likely to come from the increased size of the genomic training population (Daetwyler et al, 2008;Goddard, 2009) and increased presence of close relatives in the training population (Clark et al, 2012;Pszczola et al, 2012).The method is also well adapted to increase reliabilities of a national evaluation for novel traits with very limited phenotypic information obtained in small populations with detailed data recording but spread over different places and countries (e.g., Egger-Danner et al, 2015).…”

Review: Opportunities and challenges for small populations of dairy cattle in the era of genomics

“…The potential for new traits in modern dairy cattle breeding programs is diverse as reviewed by Boichard and Brochard (2012) and Egger-Danner et al (2015). There are at least three essential sources for new traits.…”

“…The earliest documentation for health traits in dairy cattle has been established in the Nordic countries since the 1970s (ICAR, 2012), and these data have been included in national evaluation systems (Phillipson and Lindhé, 2003). As reviewed by Egger-Danner et al (2015), routine genetic evaluations for direct health traits also exist in Austria (since 2010), in Germany (since 2010), in France (since 2012) and in Canada (since 2013). Further possible sources of information are farmers or expert groups, for instance claw trimmer or nutritionists.…”

“…Data can further arise from laboratories or onfarm equipment (ICAR, 2012). Egger-Danner et al (2015) emphasize the motivation of the involved stakeholder to be a key requirement for successful recording.…”

A glimpse of the future in animal nutrition science. 1. Past and future challenges

“…Not until recently has the obsession of consumer for "healthy" food drawn much attention to the use of antibiotics in livestock (Egger-Danner et al, 2015). The generalized concern about antimicrobial use in meat production is associated with molecule residuals and antibiotic resistance development in pathogenic species that are particularly dangerous for human health.…”