Effect of rice and other cereal grains on growth performance, pig removal, and antibiotic treatment of weaned pigs under commercial conditions1

Three experiments were conducted to evaluate effects of rice and other cereal grains on growth performance and health of weanling pigs. Pigs (1,008 in Exp. 1 and 3 and 1,004 in Exp. 2; 21 d old) with an initial BW of 5.8 ± 1.0 kg were used. Pigs in each experiment were divided into 3 BW blocks (heavy, medium, or light) in each of 4 rooms, resulting in 12 blocks per experiment. Each pen within a block had 20 or 21 pigs and equal sex distribution. Pens were allotted to dietary treatments in a randomized complete block design. Pigs were fed in a 4-phase feeding program with Phases 1 and 2 of 1 wk each and Phases 3 and 4 of 2 wk each. Diets were formulated to meet the same nutritional standards within each phase. In Exp. 1, effects of different cereal grains on pig performance and removal rate (mortality plus morbidity) were investigated. Pigs were fed 4 diets based on corn, barley, rolled oats, or rice as the only cereal grain. Over a 6-wk period, the ADG of pigs fed rice was greater (P < 0.01) than those pigs fed barley but not different from those pigs fed corn or rolled oats. Pigs fed corn or rice did not differ in ADFI, which was greater (P < 0.05) than those pigs fed barley. The overall removal rate of pigs fed rice or barley was reduced as compared with those pigs fed rolled oats (P < 0.05), and tended to be less than those pigs fed corn (P = 0.075). Experiment 2 was conducted to determine if the benefits observed in Exp. 1 could be obtained by feeding rice for less than 6 wk. Treatments included rice diets fed for 0, 1, 2, or 4 wk before changing to corn diets. All pigs received a common diet during wk 5 and 6. Pig performance and antibiotic treatments did not differ among dietary treatments. However, pigs fed rice for 1, 2, or 4 wk had a reduced overall removal rate (P < 0.05) compared with those fed corn. Experiment 3 was conducted to investigate if the amount of rice fed in wk 1 could be reduced without reducing pig performance. Rice replaced 0, 50, 75, or 100% of corn in Phase 1 diets. All pigs received a common diet from wk 2 to 6. No differences in pig performance or antibiotic treatments among dietary treatments were observed. However, pigs fed the diet with 100% rice had a reduced (P = 0.055) overall removal rate compared with pigs fed the corn diet. Generally, rice and corn improve pig performance as compared with barley. Rice can substitute for corn in nursery diets without detriment to pig performance and substantially reduces pig removals, even when fed for only 1 wk immediately after weaning.