Use of feed technology to improve the nutritional value of feed ingredients and diets fed to pigs.

摘要

Seven experiments were conducted to investigate effects of use of feed technology to improve the nutritional value of ingredients and diets fed to pigs. The objective of Exp. 1 and 2 was to determine the digestibility of CP, AA, and P, and the concentration of DE and ME, in corn ground to different particle sizes (i.e., 865, 677, 485, and 339 microm). Results of Exp. 1 and 2 indicated that the concentration of DE and ME increased (P < 0.05) linearly as the particle size of corn was reduced from 865 to 677, 485, or 339 microm, but this was not the case for CP, AA, or P digestibility. The objective of Exp. 3 was to test the hypothesis that addition of dietary lipids can be reduced as corn particle size was reduced without affecting growth performance or carcass composition of growing-finishing pigs. Results of this experiment indicated that by using corn ground to a smaller particle size, the amount of added fat may be reduced in diets fed to growing-finishing pigs without affecting animal growth performance or carcass composition, however, dressing percentage was increased (P < 0.05). Two subsequent experiments were conducted to test the hypothesis that reduced particle size of corn also will improve the caloric utilization of corn fed to weanling pigs. Results of these experiments indicated that G:F of weanling pigs was improved (P < 0.05) in diets containing corn ground to a particle size of 339 microm rather than a greater particle size, which confirmed that the ME of finely ground corn is greater than the ME of coarsely ground corn. Thus, less expensive diets may be formulated if corn is ground to a smaller particle size. In Exp. 6, the objective was to determine the effects of chemical, physical, or enzymatic treatments of distillers dried grains with solubles (DDGS) on concentration of DE and ME, and the digestibility of energy, OM, and detergent fiber. Results of Exp. 6 indicated that extrusion of DDGS or treatment with sodium hydroxide, calcium oxide, or a mixture of hemicellulases and xylanases did not improve ME or increase the digestibility of GE, OM, NDF, or ADF. However, treatment of DDGS with a mixture of cellulases and xylanases resulted in an increase (P < 0.05) in digestibility of GE and OM and increased (P < 0.05) ME compared with untreated DDGS. Experiment 7 was conducted to test the hypothesis that pelleting and extrusion of diets, either alone or in combination, will improve nutrient and energy digestibility. Results of this experiment indicated that energy utilization was improved (P < 0.05) by pelleting or extrusion or by the combination of the technologies. The response to extrusion seems to be greater in high-fiber diets than in corn-soybean meal diets, but regardless of the concentration of fiber in the diet, the combination of extrusion and pelleting always increased (P < 0.05) the utilization of energy in the diet. In conclusion, use of fine grinding, enzyme addition, or extrusion and pelleting positively influence energy and nutrient digestibility in diets fed to pigs.;Key words: amino acid, digestibility, energy, fiber, pig, feed processing.