INFLUENCE OF PARTICLE SIZE AND PRESENTATION OF FEEDS IN SWINE FEEDING
The smaller the particle size, the greater the digestibility of the nutrients and therefore a better Conversion Rate (CR) and a better Average Daily Gain (ADG).
However, the finer the particle size, the higher the incidence of digestive problems (ulcers, colitis ...), while the prevalence of Salmonella increases in the carcasses. The main reason is the greater fluidity of the stomach content and the lower effect of associated dietary fiber that has as direct repercussion a lower production of lactic acid at stomach and ileocecal valve level favoring the growth of pathogenic bacteria, such as Salmonella spp, E. coli . Therefore very fine grindings, such as those used in the granules, have as a direct effect greater constipation, higher incidence of digestive ulcers and higher incidence of nonspecific colitis.
With a coarser particle size, digestive problems are prevented and the presence of Salmonella in the carcasses is reduced.
The effect of the smaller particle size on the digestibility of energy is more pronounced in cereals (corn> barley> wheat) than in protein crops such as soybean in which the smaller particle size is more important for the better digestibility of the protein.
The recommended particle size ranges from 600-1000 μm. A recent Australian paper (AC Edwards, 2014), concludes that the reduction of the particle size from 1100 to 600-700 microns, has no effect on the GMD, but reduces consumption, resulting in a 2.6% improvement in the IC in the growth phase, and of 5.6% in the finishing phase.
If we want to make a greater adjustment depending on the production phase we can follow these recommendations:
• Piglets: 400-550 microns
• Lactating and pregnant sows: 600 (most recommended infants) - 750 microns
• Fattening pigs: 500-650 microns.
** Granulated feed ranges from 400-500 microns
Presentation of the feed (Mash vs. Granule):
It is proven that the granulated feed achieves a higher production yield. This effect is consistent on the CR and not so much, or does not exist, on the ADG.
When granulating we must avoid the fines that have a direct impact on the ADG conversion rate and incidence of ulcers.