44 Effects of Decreasing Corn Particle Size on Metabolizable Energy and Proportions of Fecal Volatile Fatty Acids in Gestating Sows

Abstract

Abstract The objective of the first experiment was to determine the effects of corn particle size on the diet apparent total tract digestibility (ATTD) of protein (CP), digestible energy (DE), metabolizable energy (ME) and N-corrected ME (AMEn) in addition to estimating the ME of corn in gestating sows. A total of 27 sows, during the second phase of gestation, were fed a common diet manufactured with corn ground to one of 3 target particle sizes (dgw): 400, 800, or 1200 µm. Titanium dioxide (0.25%) was included in the diet as an indigestible marker for digestibility calculations. Sows were fed experimental diets for 7 days to allow for diet adaptation before a 2-day collection period of urine and fecal samples. Reducing dgw of corn from 1,200 to 400 µm increased (linear, P < 0.01) ATTD CP and GE, DE, ME, AMEn and calculated ME of corn. The objective of the second experiment was to determine the effects of corn particle size on the total concentration and molar proportions of volatile fatty acids (VFA) in the feces of gestating sows. A total of 27 sows were fed treatments similar to Exp. 1 from day 61 to 82 of gestation. On day-82 and 83 of gestation, 2 fecal grab samples were collected for VFA analyses. Sows fed diets with decreasing corn dgw had increased (quadratic, P = 0.021) fecal acetic acid proportions, and decreased propionic (quadratic, P = 0.019) and valeric acid (P = 0.005). In conclusion, for every 100 µm decrease in corn dgw from 1,200 to 400 µm, corn ME value increased by 28.6 kcal/kg. Additionally, decreasing corn particle size led to an increase in the proportion of acetic acid and a decrease in propionic and valeric acid in fecal samples of gestating sows.