Operational measures of efficiency: make them measureable on large scale
Finisher pigs tend to be 3-way crossbreds kept in pens of 8-15 in Europe and 20-30 in the Americas, with many exceptions. In theory it is possible to feed finisher pigs individually, but costs and management requirements of automatic feeding systems, and availability of easy to handle decision making software limit their use on commercial farms. Management unit is, therefore, the pen, even though there is still a lot of variation among individual animals (among others, mendelian sampling). In addition, there is phenotypic variation, since piglets differ in birth weight (which is a maternal trait), in colostrum intake and in establishment of gut microbiome coming from their (foster) dam, and later depend on their pen mates influence (activity, hierarchy) and farm ambient conditions.
Measuring feed efficiency, and predicting it to feed animals according to requirements given a certain environmental condition, thus remains a challenge, but yet animal sorting options are being put into practice to optimize feeding on a pen level. Alternatives to individual electronic feeder measurements are also tested to produce individual measurements, including on-farm identification of drivers of the biological basis of feed efficiency (genomic and bio-markers) and measurements of components of feed efficiency (body composition, activity, gut microbiome composition). Feed efficiency is (still) mainly energy efficiency, and it has been the main driver of selection until now. However, energy requirements are now most often properly covered, protein efficiency is coming up and other efficiencies (vitamins, minerals) are being explored that might become of interest. In addition, by feeding animals high quality easy to digest feed, feed efficiency is essentially metabolic efficiency, but the increasing diversity of feed resources, including industry byproducts with higher dietary fiber contents, questions the opportunity to now focus on the genetic variability of digestive efficiency.
