| Scope and method of study. Two experiments were conducted to determine the effects of reducing ME (fat) level in diets containing soy protein concentrate (SPC) or spray-dried porcine plasma (SDPP) on performance of 400 crossbred pigs (avg BW = 5.8 kg avg 21 d). In Exp. 1, pigs were allotted to four dietary treatments (6--7 pigs/pen, 9 replications) in RCBD: (1) SPC, ME = 3,471 kcal/kg, (2) SDPP, ME = 3,471, (3) SDPP, ME = 3,371, and (4) SDPP, ME = 3,271. In Exp. 2, a 2 x 2 factorial in RCBD (7 pigs/pen, 6 replications) was used: (1) SPC with ME = 3,523, (2) SPC, ME = 3,323, (3) SDPP, ME = 3,523, and (4) SDPP, ME = 3,323. Pigs and feeders were weighed on d 0, 7, 14, and 18, to determine ADG, ADFI, and G:F. Exp. 3 was performed using Exp. 2 treatment design (4 pigs/trt, 5 reps, avg BW = 6.1 kg avg 18 d) to determine the effect on growth of the pancreas, stomach, and small intestine, morphology of the small intestine, levels of IgG and IgA in serum and intestinal chyme, pancreatic alpha-amylase and triglyceride lipase activities in pancreas and chyme, and gene expression of triglyceride lipase, alpha-amylase and trypsinogen.Findings and conclusions. Inclusion of SDPP in weanling pig diets improved ADG, ADFI, and G:F. Reducing ME level in SDPP diets did not affect growth performance, but linearly increased weight gain/ME intake. The improvement in weight gain/ME intake associated with reduced ME tended to be greater for pigs fed SPC than for pigs fed SDPP. Protein source or fat level did not affect lipase and amylase activity in pancreas, but SDPP increased these in intestinal chyme. CP source increased gene expression of amylase and numerically increased lipase and trypsinogen expression. Intestinal chyme IgG was significantly increased in pigs fed SDPP. Results suggest that inclusion of SDPP to weanling pig diets improves growth performance by varied mechanisms. In addition, the use of fat in weanling pig diets during the first 2 wk post-weaning may have no benefit to pig growth. |
