Two experiments at the Prestage Department of Poultry Science examine the interactions between maize and soybean particle sizes, nutrient digestibility and broiler growth. Gizzard weight was more affected by the particle size of the maize in the diet than the soybean meal.
Although there have been several reports concerning the effects of particle size of cereal grains on productive performance of poultry, there is limited information about the effects of soybean meal (SBM) particle size on broiler performance, according to W.J. Pacheco and colleagues at North Carolina State University.
The objective of these two experiments – reported in Poultry Science – was to evaluate the effects of SBM source and particle size on broiler performance, gizzard weight and nutrient digestibility.
The first experiment was a 2×2 factorial arrangement of two SBM sources: expeller-extracted (ESBM) and solvent-extracted (SSBM), and two particle sizes: coarse grind (971µm) and fine grind (465µm).
The second experiment was a 2×2 factorial arrangement of two ESBM particle sizes: coarse grind (1,290µm) and fine grind (470µm) and two corn particle sizes: coarse grind (1,330µm) and fine grind (520µm).
In the first experiment, there was an interaction (P<0.05) between SBM source and particle size on bodyweight at 49 days of age. No differences in bodyweight were observed when birds were fed coarse SSBM or ESBM, whereas birds fed diets containing fine ESBM exhibited lower bodyweights than those fed diets containing fine SSBM.
In the second experiment, fine-grind ESBM (P<0.05) and corn (P<0.01) produced greater 19-day bodyweight than did coarse grind. A significant interaction (P<0.01) between ingredient type and particle size revealed that chicks fed coarse particles of corn or ESBM exhibited higher protein digestibility than those fed only fine particles.
Corn particle size had a greater effect on gizzard weight than ESBM particle size.
Birds fed diets that contained coarse corn had larger gizzards than birds fed fine corn (P<0.01) but differences in gizzard weight were not observed when birds were fed coarse or fine ESBM.
Particles greater than 1,300µm depressed bodyweight but improved protein digestibility, according to Pacheco and co-authors.
Pacheco W.J., C.R. Stark, P.R. Ferket and J. Brake. 2013. Evaluation of soybean meal source and particle size on broiler performance, nutrient digestibility, and gizzard development. Poult. Sci. 92(11):2914-2922. doi: 10.3382/ps.2013-03186