Pelleting swine diet is an effective processing method for improving growth performance of pigs. Multiple factors including decreased feed wastage, increased nutrient digestibility, and improved palatability may influence this effect. Differently, fine grinding is another feed processing method that improves feed efficiency. However, there is poor information available on the impact of feeding pelleted diets containing corn ground finer than 700 μm in 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 1 of 6 experimental treatments with 8 pens per treatment and 20 pigs per pen. The 6 experimental treatments were arranged in a 2 × 3 factorial with main effects of final feed form (meal vs. pellet) and corn particle size (650 μm, 350 μm, or an equal blend of the 650 μm and 350 μm ground corn). The 650 μm corn was ground using a two-high roller mill, and the 350 μm 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 × diet form interactions were observed 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 average daily gain (ADG) compared with pigs fed meal diets. As corn particle size decreased, ADG decreased (linear). Pigs fed pelleted diets had increased hot carcass weight compared with pigs fed meal diets, but no other effects on carcass characteristics were observed.
In summary, pigs fed pelleted diets had improved average daily gain compared with those fed meal diets. Feed efficiency improved as corn particle size decreased for pigs fed meal diets but not for those fed pelleted diets, suggesting that grinding corn finer than 650 μm for pelleted diets conferred no benefit.
Nemechek, J. E., Tokach, M. D., Dritz, S. S., Goodband, R. D., DeRouchey, J. M., and Woodworth, J. C. (2016). Effects of diet form and corn particle size on growth performance and carcass characteristics of finishing pigs. Animal Feed Science and Technology, 214, 136-141. https://doi.org/10.1016/j.anifeedsci.2016.02.002