REDUCING PARTICLE-SIZE OF CORN IN LACTATION DIETS FROM 1,200 TO 400 MICROMETERS IMPROVES SOW AND LITTER PERFORMANCE

One hundred primiparous sows were used to determine the effects of par ticle size of corn in lactation diets on sow and litter performance. T he sows were fed a corn-soybean meal-based diet with the corn ground t o 1,200, 900, 600, or 400 mu m. Particle size of corn had no influence on sow BW or backfat loss (P > .30), subsequent weaning-to-estrus int erval (P > .40), or percentage of sows returning to estrus (P > .09). However, ADFI was increased (linear effect, P < .04) as particle size was reduced from 1,200 to 400 mu m. Pig survivability was not affected (P > .30) but litter BW gain was increased by 11% when sows were fed diets with 400 vs 1,200 mu m corn (linear effect, P < .05). Apparent d igestibilities of DM, N, and GE were increased by 5, 7, and 7%, respec tively, as particle size was reduced from 1,200 to 400 mu m (linear ef fects, P < .001). Intake of DE was increased 14% (13.7 to 15.6 Mcal/d) as corn particle size was reduced from 1,200 to 400 mu m. Intakes of digestible DM and N also were increased (11 and 14%, respectively), wh ereas fecal excretions of DM and N were decreased by 21 and 31%, respe ctively (linear effects, P < .001). Reducing particle size increased s everity of ulceration and keratinization (nonzero correlations of P < .04 and P < .004, respectively) in the esophageal region of the stomac h, although the changes were not associated with reduced sow performan ce. In conclusion, our data indicate that the optimum particle size of corn in lactation diets to maximize nutrient intake and litter weight gain in primiparous sows is near 400 mu m.