Feed particle size and pig nutrition

Abstract

Particle size description of diets for swine is not included in the nutritional recommendations from major scientific organisations world-wide. Nevertheless, the effect of particle size as a source of variation of the nutritional value of grains for swine, and as an etiological factor for digestive disorders has been demonstrated through a large number of reported works. A quantitative database was built from data from 23 scientific papers and internal reports, in order to derive response laws to particle size variation for nutritional value. In growing swine (weaned piglets and growing-finishing pigs), energy faecal digestibility is reduced by 0.6 unit and nitrogen faecal digestibility by 0.8 unit when particle size increases by 100 μm. Among technical parameters, only feed conversion (FCR) of piglets is related to particle size: an FCR increase of 0.03 unit corresponded to a 100 μm increase in average particle size. These ranges are low compared with other sources of variation in digestive or metabolic use of diets.

Studying the influence of particle size is complicated by the integration of indirect effects on nutritional value, such as mix stability, or by interactions with elementary steps of the process other than grinding (example: pelleting). Moreover, optimal particle size selection depends on factors other than nutritional-like flowing properties of the meal: feed restriction due to poor flowing properties is still a real concern. Technical constraints nowadays still override nutritional benefits in the decision making process for high quality meal.