Controlling Salmonella infection in weanling pigs through water delivery of direct-fed microbials or organic acids. Part I: effects on growth performance, microbial populations, and immune status.

Pigs (n = 88) weaned at 19 ± 2 d of age were used in a 14-d study to evaluate the effects of water-delivered direct-fed microbials (DFM) or organic acids on growth, immune status, Salmonella infection and shedding, and intestinal microbial populations after intranasal inoculation of Salmonella Typhimurium (10(10) cfu/pig). Pigs were challenged with Salmonella 6 d after commencement of water treatments. Treatments were 1) control diet; 2) control diet + DFM (Enterococcus faecium, Bacillus subtilis, and Bacillus licheniformis) in drinking water at 10(9) cfu/L for each strain of bacteria; 3) control diet + an organic acid-based blend (predominantly propionic, acetic, and benzoic acid) in drinking water at 2.58 mL/L; and 4) control diet + 55 mg/kg of carbadox. Serum samples were taken on d 6, 8, 10, and 14 for determination of tumor necrosis factor α (TNFα) concentrations. Fecal samples were taken on d 0, 5, 7, and 11 for determination of Salmonella shedding and enumeration of coliforms. Pigs were euthanized on d 6, 8, 10, and 14. Intestinal and cecal tissue and digesta and mesenteric lymph nodes were sampled and analyzed for Salmonella. Duodenal, jejunal, and ileal mucosal scrapings were sampled for measurement of mucosal TNFα concentrations. Water delivery of DFM prevented a decline in ADG on d 2 to 6 postchallenge compared with the negative control (P < 0.05). Coliform counts tended to be greater (P = 0.09) in the cecum of the DFM treatment group on d 2 postinfection compared with the negative control and acid treatment groups. However, Salmonella prevalence in the feces, gastrointestinal tract, or lymph nodes was not affected by water delivery of acids or DFM. Serum and mucosal TNFα concentrations were not affected by treatment throughout the study with the exception of ileal concentrations on d 4 postchallenge, which were greater in the negative control group compared with all other treatments (P < 0.05). The in-feed antibiotic was the only treatment that reduced Salmonella prevalence and this was localized to the cecum on d 8 postinfection. In conclusion, the DFM and organic acid treatments used in this study offered little or no benefits to pigs infected with Salmonella and should not be considered under the constraints of this study as viable alternatives to in-feed antibiotics in a pathogen challenge situation.

Periparturient cortisol, acute phase cytokine, and acute phase protein profiles of gilts housed in groups or stalls during gestation.

Use of gestation stalls in pork production remains a controversial topic in animal welfare. Immune status and measures are frequently used to assess stress levels and thus well-being of confined animals. The important welfare issue of close confinement among gestating gilts was tested by quantifying cortisol, acute phase cytokine, and acute phase protein pro-files before and after farrowing of gilts housed in 2 systems. Landrace x Yorkshire crossbred gilts housed in groups of 4 (group, n = 8) in pens (3.9 x 2.4 m with 4 individual feeding spaces, 9.36 m(2) total or 2.34 m(2)/gilt) were compared with gilts housed in standard industry stalls (stall, n = 16; 2.2 x 0.6 m, 1.32 m(2)/gilt). Floors were fully slatted, and a substrate was not provided for either system. Cortisol was determined from saliva on d 105 of gestation, 1 h after moving the gilts into farrowing stalls (d 111), and 24 h and 7 d after farrowing. Cortisol was greater (P = 0.04) for group gilts compared with stall gilts 1 h after moving them into farrowing stalls and 24 h after farrowing. Cortisol concentrations decreased (P = 0.001) over time. Leukocyte mRNA expression of IL-1, IL-1 receptor antagonist, and tumor necrosis factor-alpha was determined by quantitative, reverse transcription PCR on d 35, 63, and 91 of gestation and 72 h after farrowing. Cytokine mRNA expression of peripheral blood mononuclear cells did not differ between housing systems for IL-1, its receptor antagonist, or for tumor necrosis factor-alpha. Acute phase proteins, including fibrinogen, haptoglobin, and alpha(1)-acid glycoprotein were determined for plasma samples taken at d 35, 63, and 91 of gestation and 72 h and 14 d after farrowing. In contrast to cortisol, plasma fibrinogen concentrations increased (P < 0.005) over time. Haptoglobin did not differ between treatments (P > 0.10). Stall gilts tended to have greater (P = 0.07) plasma alpha(1)-acid glycoprotein concentrations than group animals at d 35 of gestation and d 14 after farrowing. These data showed a trend (P < 0.07) for alpha(1)-acid glycoprotein concentrations to return to baseline more quickly in group-housed gilts, which did not appear to be directly related to increased cortisol just before farrowing. In conclusion, few differences in the acute phase response were detected between housing systems, suggesting that the resting immunological responses are only mildly affected by gestation stalls.

Postnatal behavioral and physiological responses of piglets from gilts housed individually or in groups during gestation.

Gestational housing of sows remains a controversial issue that may affect the well-being of both sows and piglets. Therefore, 2 types of gestational housing were used to evaluate the stress imposed on pregnant gilts by each system and the effects on the offspring by comparing production, physiology, and behavioral measures of the piglets. Forty-eight Landrace x Yorkshire gilts were randomly assigned to groups (G) of 4 per pen (n = 8 pens; 3.9 m x 2.4 m) or to individual stalls (S; n = 16 stalls; 2.21 m x 0.61 m). Gilts were moved into individual farrowing crates 5 d before the expected farrowing date. Piglets were weighed at birth, d 14, and d 35. Two barrows from each litter were weaned at d 14 (early weaning) and housed together in pens. Maintenance behaviors (head in feeder, drinking, lying, eating mash) were videotaped and observed for the first 3 d after weaning using a 10-min interval scan sampling. Belly nosing and play/fight interactions were recorded from video observations for 3 d postweaning. An isolation test (30-min duration) was performed on one piglet from each pen of barrows on d 35. Time spent lying, the number of jumps against test box walls, and grunts and squeals were recorded in real time. Salivary cortisol was collected at 30-min intervals from baseline, and 0, 30, 60, and 90 min posttest. Jugular blood was collected from 2 barrows from each litter on d 1, 7, 14, 17, 21, and 28. Plasma TNF-alpha was analyzed by ELISA, and haptoglobin, alpha1-acid glycoprotein, and immunoglobulin G were analyzed by radial immunodiffusion. More piglets from the S treatment needed to be fed a liquid feed at weaning and drank more frequently on d 2 postweaning (P < 0.05). Additionally, by d 35 piglets from S gilts had a lighter BW (10.3 kg) than G piglets (12.8 kg; P < 0.01). Piglets from S gilts also grunted more during the 30-min isolation test (number of grunts = 356) than G piglets (number of grunts = 138; P < 0.01). Salivary cortisol and immune measures were not different. These data show some behavioral and production differences between piglets from individually stalled gilts and group-housed gilts. Therefore, there may be production advantages to housing first parity gilts in groups.

Effects of lactation length and an exogenous progesterone and estradiol-17beta regimen during embryo attachment on endogenous steroid concentrations and embryo survival in sows.

The hypotheses that short lactation lengths increase embryo mortality by altering endogenous post-weaning steroid concentrations, and that an exogenous steroid regimen during embryo attachment might increase embryo survival were tested using 36 s parity sows assigned randomly to a 2 x 2 factorial. Sows were subjected to either a short lactation (SL, 13.0 days, n = 25) or a long lactation (LL, 31.5 days, n = 11), artificially inseminated at first estrus and treated daily with 2 ml i.m. of either 25 mg progesterone (P4) and 1.25 pg estradiol-17beta (E2) (steroid treatment, ST, n = 17) or the vehicle alone (control treatment, CT, n = 17) on Days 14-20 post-insemination. Blood samples were collected by jugular venipuncture from weaning to 24 days post-insemination on alternate days. Sows subjected to the SL compared to the LL tended to have a longer weaning-to-estrus interval (WEI) (5.3 versus 4.6 days; P < 0. 10), but did not have a significantly reduced conception rate (CR) (71 versus 90%; P > 0.10). The SL and LL sows had a similar ovulation rate (19.9 versus 21.3 corpora lutea, CL; P > 0.05), but SL sows had fewer viable embryos than LL sows (11.5 versus 15.3; P < 0.05) when reproductive tracts were recovered 28-32 days post-insemination. In addition, even after correction for the difference in number of embryos between groups, viable embryos from the SL versus the LL group weighed less (1.63 versus 1.79 g; P < 0.05), had a decreased amnion volume (1.02 versus 1.22 ml; P < 0.05) and apparently produced less estrogens since estrone sulfate concentration was decreased at 24 days post-insemination in SL versus LL sows (4.3 versus 6.3 ng/ml; P < 0.05). Embryo survival (percentage of CL represented by a viable embryo) however, was not different between SL and LL sows (60 versus 74%; P > 0.05) and no differences in post-weaning P4 or E2 concentrations were apparent. Sows that received the ST only tended to have increased P4 concentrations at 16 days post-insemination compared to CT sows and neither the number of viable embryos, nor embryo survival, was increased in ST versus CT sows (14.7 versus 12.2; P > 0.05 and 66 versus 68%; P > 0.05, respectively). These data suggest that short lactations do not increase embryo mortality by inducing aberrant endogenous post-weaning P4 or E2 concentrations. It is unclear whether or not small, repeated doses of exogenous P4 and E2 during attachment can increase embryo survival.