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Effects of wheat source and particle size in pelleted diets on finishing pig growth performance and caloric efficiency
A total of 576 pigs (PIC 327 × 1050; initial BW = 43.6 kg) were used to determine the effects of wheat source and particle size on finishing pig growth performance, and caloric efficiency (CE). The same wheat-soybean meal–based formulation was used for all treatments. Pigs were allotted to 1 of 6 dietary treatments (12 pens/treatment with 8 pigs/pen) which included either hard red or soft white winter wheat at three different mean particle sizes (245, 465, 693; and 258, 402, 710 µ, respectively). All diets were fed in pelleted form (4 mm diameter pellets). Pellet durability was improved at the lowest particle sizes for both hard red (88.5, 81.2, 74.2%) and soft white (54.5, 50.9, 48.7%) winter wheat. Percentage fines were similar across wheat sources (24.0, 22.9, 26.9 vs 22.2, 27.2, 24.1%). There was a tendency (P<0.07) for a quadratic particle size × wheat source interaction for ADG (1.03, 1.01, 1.03 vs 0.97, 1.00, 0.99: SEM=0.01), ADFI (2.66, 2.59, 2.67 vs. 2.54, 2.58, 2.56; SEM=0.03), and both DM (87.7, 87.0, 88.0 vs. 85.8, 87.7, 85.1; SEM=0.80) and GE (68.3, 64.5, 66.3 vs. 62.3, 67.5, 64.9; SEM=1.94) digestibility because the lowest ADG, ADFI, and both DM and GE digestibility values were for 400-µ hard red winter wheat, and the highest were for 400-µ soft white winter wheat. Despite this trend for interaction; overall, feeding hard red winter wheat improved (P<0.05) ADG (1.02 vs. 0.99 kg; SEM=0.008), ADFI (2.64 vs. 2.56 kg; SEM=0.02), and CE on both an ME (8.13 vs. 8.50 Mcal/kg; SEM=0.17) and NE (4.63 vs. 4.77 Mcal/kg; SEM=0.25) basis compared with soft white winter wheat. There were no main effects (P>0.10) of particle size or particle size within wheat source. In summary, fine grinding wheat from ̴ 700 to 250 µ in pelleted diets had no effect on growth or carcass traits and feeding hard red winter wheat improved ADG, ADFI, and caloric efficiency (ME and NE basis) compared with feeding soft white winter wheat.
Keywords: finishing pig, particle size, pellet, wheat