Abstract
The effects of corn particle size on nutrient digestibility and energy utilization in pigs were determined under optimal (experiment 1, 25 ± 1 °C) or heat stress (experiment 2, 37 ± 1 °C) conditions. In Exp. 1 and 2, five experimental diets were tested using a 5 × 5 Latin square design involving five barrows (Landrace × Yorkshire × Duroc, average initial body weight of 30 ± 1 kg and 45.0 ± 1.8 kg, respectively, in individual metabolic cages). Dietary treatments were as follows: 200-, 300-, 400-, 600-, 800-μm corn particle sizes obtained by mesh screens. Under optimal thermal conditions, digestibility of dry matter (DM) and crude fiber (CF) from 200-μm diet was higher (P < 0.05) compared to that from the 300-μm and 400-μm diets. The digestibility of crude protein (CP) and ether extract (EE) was the highest (P < 0.05) at the 200-μm particle size. The apparent total tract digestibility of energy was significantly higher (P < 0.05) on the 200-μm diet. Under heat stress, digestibility of CF when corn was ground to 600 μm was higher (P < 0.05) compared to 300 and 400 μm. Digestibility of NDF and ADF was the highest (P < 0.05) at 600-μm corn particle size. In conclusion, grinding corn to 200-μm corn particles had a positive effect on DM, CP, EE, and CF under optimal thermal condition, while the 600-μm corn particle size had positive effects on digestibility of CF, NDF, and ADF than 200-μm corn particle size under heat stress.
Highlights
In modern pig farming, feed accounts for a major part of production costs
Reducing the particle size of cereal grains to 600 μm has been shown to result in greater nutrient digestibility, rate of growth, and lactation performance, and decreased fecal excretion of nutrients, when compared with the effects of diets of coarser particle sizes between 900 and 1000 μm (Wondra et al 1995b)
Intakes of dry matter (DM), crude protein (CP), ether extract (EE), crude fiber (CF), CA, NDF, and ADF were different among treatments (P < 0.05)
Summary
In this regard, reducing the particle size of cereal grains by cracking, crimping, rolling, or grinding via mechanical force can increase the surface area and improve digestibility (Ohh et al 1983). This improvement in nutrient digestibility and gain/feed ratio is attributed to an increase in the area of contact with digestive enzymes (Kim et al 2000; Hancock et al 2000).
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