We previously showed that phosphorylation of p70 S6 kinase (p70 S6k ) in the intestine is increased during viral enteritis. In this study, we hypothesized that during rotavirus infection, oral Arg, which stimulates p70 S6k activation, will further stimulate intestinal protein synthesis and mucosal recovery, whereas the p70 S6k inhibitor rapamycin (Rapa) will inhibit mucosal recovery. Newborn piglets were fed a standard milk replacer diet supplemented with Arg (0. Jejunal villi of the Rapa-treated group showed inactivation of p70 S6k and a decrease in mucosal resistance (reflecting increased permeability), the latter of which was reversed by Arg. We conclude that, early in rotavirus enteritis, Arg has no impact on diarrhea but augments intestinal protein synthesis in part by p70 S6k stimulation, while improving intestinal permeability via a mammalian target of rapamycin/p70 S6k -independent mechanism.

The effects of feeding different sources of immunoglobulins (sow's colostrum by nursing, SC; no colostrum, NC; bovine colostrum, BC; and porcine immunoglobulins, PI) to neonatal pigs during the first 2 d of life on their subsequent survival, growth, feed intake, feed conversion, incidence of diarrhea, and selected hematological and immunological variables were assessed throughout a 19-d experimental period. After d 2, all pigs were fed the same liquid basal diet. Crossbred neonatal pigs, 10 per treatment, were individually reared after birth (NC, BC, and PI) or 2 d of age (SC) with an automatic feeding device. All pigs of treatments SC and PI, and 80 and 30% (P < .01) of pigs of treatments BC and NC, respectively, survived to the end of the trial. Growth, feed intake, and feed conversion efficiency (gain/feed) of surviving pigs were similar (P > .05), regardless of treatment. A transient physiological scours was observed in 20 to 50% of the pigs between 5 and 7 d of age; by 10 d of age, all pigs had solid feces. Hemoglobin concentration and hematocrit in blood of pigs of treatment NC were lower (P < .05) than those of the other treatments. Concentrations of total serum proteins, trichloroacetic acid-precipitable proteins, and serum IgG of SC pigs were higher (P < .01) than those of pigs in the other treatments. These results showed that porcine immunoglobulins or bovine colostrum can be satisfactorily used as immunoglobulin sources in artificial rearing of colostrum-deprived neonatal pigs.

Recent identification of the mammalian target of rapamycin (mTOR) pathway as an amino acid-sensing mechanism that regulates protein synthesis led us to investigate its role in rotavirus diarrhea. We hypothesized that malnutrition would reduce the jejunal protein synthetic rate and mTOR signaling via its target, ribosomal p70 S6 kinase (p70S6K). Newborn piglets were artificially fed from birth and infected with porcine rotavirus on day 5 of life. Study groups included infected (fully fed and 50% protein calorie malnourished) and noninfected fully fed controls. Initially, in “worst-case scenario studies,” malnourished infected piglets were killed on days 1, 3, 5, and 11 postinoculation, and jejunal samples were compared with controls to determine the time course of injury and p70S6Kactivation. Using a 2 × 2 factorial design, we subsequently determined if infection and/or malnutrition affected mTOR activation on day 3. Western blot analysis and immunohistochemistry were used to measure total and phosphorylated p70S6K; [3H]phenylalanine incorporation was used to measure protein synthesis; and lactase specific activity and villus-crypt dimensions were used to quantify injury. At the peak of diarrhea, the in vitro jejunal protein synthetic rate increased twofold (compared with the rate in the uninfected pig jejunum), concomitant with increased jejunal p70S6Kphosphorylation (4-fold) and an increased p70S6Klevel (3-fold, P < 0.05). Malnutrition did not alter the magnitude of p70S6Kactivation. Immunolocalization revealed that infection produced a major induction of cytoplasmic p70S6Kand nuclear phospho-p70S6K, mainly in the crypt. A downregulation of semitendinosus muscle p70S6Kphosphorylation was seen at days 1–3 postinoculation. In conclusion, intestinal activation of p70S6Kwas not inhibited by malnutrition but was strongly activated during an active state of mucosal regeneration.

Feeding manufactured liquid diets to early-weaned pigs improves growth performance and reduces days to market weight compared with pigs receiving pelleted dry feed. Few alternative dietary ingredients are utilized in manufactured liquid diets other than byproducts of the dairy industry, especially for sources of carbohydrates. This experiment was designed to evaluate the efficacy of starch from partially hydrolyzed corn syrup solids (CSS), at two different levels of hydrolyzation, as a replacement for lactose in manufactured liquid diets. Forty-eight pigs were removed from sows at 1 d of age and randomly assigned to one of three treatments: 1) control with lactose as the carbohydrate source, 2) lactose replaced (gram for gram) with CSS (dextrose equivalent [DE]-20), and 3) lactose replaced with DE-42. In addition, 10 pigs were randomly removed from several litters to provide estimates of initial body composition and small intestinal variables. Twenty-four pigs were removed from the study on d 10 of treatment, and the remaining 24 pigs were removed on d 20 of treatment. Pigs averaged 9,845 +/- 191 g at d 20 of treatment regardless of dietary treatment (P > 0.20). No differences in ADG, ADFI, or feed efficiency were detected between treatment groups from d 0 to 20 (P > 0.19). Whole-body water, protein, lipid, and ash accretion rates were unaffected by dietary treatment from d 0 to 10 or from d 0 to 20 (P > 0.20). The replacement of lactose with CSS did not affect intestinal villi height or width, or crypt depth (P > 0.10). Pigs fed lactose tended to have greater lactase activity on d 10 than pigs fed CSS (P < 0.07). Also, pigs fed lactose tended to have lower oligosaccharidase activity than pigs fed the DE-20 diet on d 20 (P < 0.07). No other differences in lactase, maltase, or long oligosaccharidase specific activity on d 10 or 20 of treatment were detected (P > 0.12). Plasma urea nitrogen concentrations were unaffected by diet on d 10 and 20 of treatment. In addition, dry matter digestibility of the diets averaged approximately 85.6 +/- 0.8% and was unaffected by dietary treatment or day of treatment. These results suggest that partially hydrolyzed CSS can be used as a replacement for lactose in manufactured liquid diets for neonatal pigs.

Addition of arachidonic acid (AA) and docosahexaenoic acid (DHA) to infant formula promotes visual and neural development. This study was designed to determine whether the source of dietary long-chain polyunsaturated fatty acids (LCPUFA) affected overall animal health and safety. Piglets consumed ad libitum from 1 to 16 d of age a skim milk-based formula with different fat sources added to provide 50% of the metabolizable energy. Treatment groups were as follows: control (CNTL; no added LCPUFA), egg phospholipid (PL), algal/fungal triglyceride (TG) oils, TG plus PL (soy lecithin source) added to match phospholipid treatment (TG + PL) and essential fatty acid deficient (EFAD). Formulas with LCPUFA provided 0.6 and 0.3 g/100 g total fatty acids as AA and DHA, respectively. CNTL piglets had 40% longer ileal villi than PL piglets (P < 0.03), but the TG group was not different from the CNTL group. Gross liver histology did not differ among any of the formula-fed groups (P > 0.1). Apparent dry matter digestibility was 10% greater in CNTL, TG and TG + PL groups compared with PL piglets (P < 0.002). No differences in alanine aminotransferase were detected among treatments, but aspartate aminotransferase was elevated (P < 0.03) in PL piglets compared with TG + PL piglets. Total plasma AA concentration was greater in the TG group compared with CNTL piglets (P < 0.05). Total plasma DHA concentrations were greater in TG piglets compared with PL (P < 0.06) or CNTL (P < 0.02) piglets. These data demonstrate that the algal/fungal TG sources of DHA and AA may be a more appropriate supplement for infant formulas than the egg PL source based on piglet plasma fatty acid profiles and apparent dry matter digestibilities.