Effects of diet form and corn particle size on growth performance and carcass characteristics of finishing pigs

A total of 960 crossbred pigs, initially 34.3 +/- 0.50 kg, were used in a 101-day trial to determine the effects of corn particle size and diet form on growth performance and carcass characteristics of finishing pigs. Pens were randomly allotted by initial weight to I of 6 experimental treatments with 8 pens per treatment and 20 pigs per pen. The 6 experimental treatments were arranged in a 2 x 3 factorial with main effects of final feed form (meal vs. pellet) and corn particle size (650 mu m, 350 mu m, or an equal blend of the 650 mu m and 350 mu m ground corn). The 650 mu m corn was ground using a two-high roller mill, and the 350 mu m corn was ground using a full circle hammer-mill equipped with a 1.59 mm screen. After all corn was ground, the diet containing the blend of particle sizes was manufactured by adding equal portions of the 2 at the mixer. Overall (day 0-101), linear particle size x diet form interactions were observed (P<0.05) for average daily feed intake (ADFI) and gain:feed ratio (G:F), because ADFI decreased and G:F increased as particle size was reduced for pigs fed meal diets but was unchanged for pigs fed pelleted diets. Pigs fed pelleted diets had increased (P<0.05) average daily gain (ADG) compared with pigs fed meal diets. As corn particle size decreased, ADG decreased (linear; P<0.05). Pigs fed pelleted diets had increased (P<0.05) hot carcass weight compared with pigs fed meal diets, but no other effects on carcass characteristics were observed. In summary, grinding corn finer than 650 mu m decreased ADFI and improved G:F for pigs fed meal diets, but did not affect performance of pigs fed pelleted diets. Pigs fed pelleted diets had improved ADG compared with those fed meal-based diets. Thus, grinding corn finer than 650 mu m improved feed efficiency for pigs fed meal diets, but provided no benefit in pelleted diets. Published by Elsevier B.V.