Effect of dietary fiber and diet particle size on nutrient digestibility and gastrointestinal secretory function in growing pigs

Pelleting and particle size reduction of corn increase net energy and digestibility of fiber, protein, and fat in corn-soybean meal diets fed to group-housed pigs

BACKGROUND

Reduction of the particle size of corn increases energy digestibility and concentrations of digestible and metabolizable energy. Pelleting may also reduce particle size of grain, but it is not known if there are interactions between particle size reduction and pelleting. The objective of this experiment was to test the hypothesis that particle size reduction and pelleting, separately or in combination, increase N balance, apparent total tract digestibility (ATTD) of fiber and fat, and net energy (NE) in corn-soybean meal diets fed to group-housed pigs.

METHODS

Six corn-soybean meal-based diets were used in a 3 × 2 factorial design with 3 particle sizes of corn (i.e., 700, 500, or 300 μm) and 2 diet forms (i.e., meal or pelleted). Pigs were allowed ad libitum access to feed and water. Twenty-four castrated male pigs (initial weight: 29.52 kg; standard diviation: 1.40) were allotted to the 6 diets using a 6 × 6 Latin square design with 6 calorimeter chambers (i.e., 4 pigs/chamber) and 6 periods. Oxygen consumption and CO2 and CH4 productions were measured during fed and fasting states and fecal and urine samples were collected.

RESULTS

Regardless of particle size of corn, the ATTD of gross energy (GE), N, and acid-hydrolyzed ether extract (AEE), and the concentration of NE were greater (P < 0.05) in pelleted diets than in meal diets. Regardless of diet form, the ATTD of GE, N, and AEE, and the concentration of NE were increased (linear; P < 0.05) by reducing the particle size of corn, but the increase was greater in meal diets than in pelleted diets (interaction; P < 0.05).

CONCLUSIONS

Both pelleting and reduction of corn particle size increased nutrient digestibility and NE, but increases were greater in meal diets than in pelleted diets.

Enhancing digestibility of corn fed to pigs at two stages of growth through management of particle size using a hammermill or a roller mill

The experimental objective was to determine the role of mean particle size (PS), grinding method, and body weight (BW) category on nutrient, fiber, and energy digestibility of corn. A total of 48 barrows were housed in individual pens and randomly assigned to one of six dietary treatments for 11 d at two BW categories (55 kg and 110 kg). The six treatments consisted of corn ground at three different targeted mean PSs (300, 500, and 700 µm) using either a roller mill or a hammermill. Fecal samples were collected for the last 3 d of each feeding period. Titanium dioxide was used as an indigestible marker. Digestibility data were analyzed as a linear mixed model using the MIXED procedure of SAS. Finishing pigs had greater apparent total tract digestibility (ATTD) of dry matter (DM), gross energy (GE), and N than growing pigs (P = 0.02, P = 0.01, and P <0.01, respectively). The ATTD of DM, GE, and N was similar in pigs fed hammermilled corn across all PS treatments. However, in roller-milled corn, they increased as PS was reduced (P < 0.05). The ATTD of acid-hydrolyzed ether extract (AEE) in growing pigs was similar between corn ground at 700 and 500 µm, but it was increased by further reducing PS to 300 µm (P < 0.05). In finishing pigs, the ATTD of AEE increased as mean PS decreased from 700 to 300 µm (P < 0.05). The ATTD of AEE was similar in hammermilled corn at all three PS treatments. On the other hand, the ATTD of AEE was similar in corn ground in a roller mill to 700 and 500 µm, but it increased when PS was reduced to 300 µm (P < 0.05). In conclusion, reducing PS of corn with a roller mill increased digestibility of energy and nutrients, but there was less effect using a hammermill. It is possible that differences in SD, distribution, chemical composition, and the shape of the particles resulting from the two grinding processes help to explain the different response.

Effects of mono-component xylanase supplementation on nutrient digestibility and performance of lactating sows fed a coarsely ground diet

The objective of the current study was to investigate the effect of supplementing a mono-component xylanase to a coarsely ground lactation diet (feed fraction particle size above 2 mm was more than 17%) based on wheat, barley, and soybean meal on nutrient digestibility and performance of lactating sows. A total of 30 cross-bred (Danish Landrace × Yorkshire) multiparous sows (parity 2 to 5) were used. Sows were fed a standard gestation diet from mating until day 108 of gestation, and then stratified for BW (295.4 ± 26.1 kg average BW) and parity to receive one of two dietary treatments (n = 15 per treatment), a lactation diet without (control diet) or with supplemented enzyme (enzyme diet). The enzyme applied was a mono-component xylanase dosed at 200 enzyme unit (FXU) per kg of feed, which corresponds to 200 g per ton of feed. The diets were fed until weaning at day 28 of lactation. On day 2 of lactation, litter size of each sow was adjusted to 14 piglets within treatment. Reproductive performance of the sows, growth of the piglets, yield and composition of sow milk, plasma metabolites and apparent total tract digestibility (ATTD) of nutrients were measured. Supplementation of xylanase had no effect (P > 0.05) on total born and live born piglets or stillbirth rate (%) at parturition. Initial parameters on day 2 of lactation including sow BW and back fat thickness, litter size, piglet weight, and litter weight were similar (P > 0.05) between treatments. Piglet weight gain, litter weight gain, litter size, and daily milk yield did not differ (P > 0.05) between treatments. The ADFI was increased by 4.5% (P < 0.01), and BW loss during the whole lactation was reduced from -13.6 to -5.2 kg (P = 0.04) with xylanase addition when compared to control sows. The ATTD of GE (83.9 vs. 82.9, P < 0.01), DM (84.2 vs. 83.4, P < 0.01), N (83.4 vs. 81.7, P = 0.02), OM (86.5 vs. 85.7, P < 0.01) and total nonstarch polysaccharides (NSP; 59.4 vs. 56.7, P = 0.02) were all increased by xylanase supplementation. Milk composition and plasma metabolites were not affected (P > 0.05), except that plasma triglycerides content was increased by xylanase addition (0.23 vs. 0.20 mM, P = 0.04). In conclusion, supplementing a mono-component xylanase to a coarsely ground lactating diet based on wheat, barley, and soybean meal improved sow feed intake and nutrient digestibility, thereby reducing sow BW loss throughout lactation, whereas milk yield and piglet performance were not affected.