Osteochondrosis prevalence and severity at 12 and 24 weeks of age in commercial pigs with and without organic-complexed trace mineral supplementation.

Maternal and progeny diets supplemented with 2 sources of trace mineral (TM) were evaluated for effects on the size and severity of osteochondrosis (OC) lesions in progeny produced by 64 Landrace × Large White sows. At breeding, sows were randomly assigned to maternal diets (gestation and lactation) consisting 1 of 2 TM treatments. One treatment consisted of inorganic TM (ITM) with ZnO, MnSO, and CuSO at concentrations to provide 150, 50, and 16.5 mg/kg diet of Zn, Mn, and Cu, respectively. The other treatment consisted of the same ITM concentrations plus an additional 50, 20, and 10 mg/kg diet of Zn, Mn, and Cu, respectively, supplied by a blend of AA-complexed TM (CTM) using Availa Sow. Within maternal dietary treatment groups, selected progeny ( = 280) were fed either ITM- or CTM-supplemented diets. The humerus and femur (1 each) from progeny euthanized at 12 ( = 80) or 24 wk ( = 200) were collected for microscopic (12 wk) or gross (24 wk) assessment of OC lesions. Microscopic OC lesions were present in all pigs at 12 wk. Dietary treatments had limited effects on OC prevalence or severity. A maternal × progeny diet interaction ( = 0.044) revealed femoral OC latens lesions that were approximately twice the size in progeny fed CTM that were produced by sows fed CTM compared with those found in pigs in the other 3 dietary treatment groups. At 24 wk, the sum of gross OC scores at predilection sites of the thoracic (elbow joint) and pelvic (stifle and hock joints) limbs remained similar among treatments, despite greater ( = 0.004) gross OC scores of the medial femoral condyle in progeny from sows fed CTM diets than in progeny from sows fed ITM diets, regardless of progeny diet. Progeny produced by sows fed CTM vs. ITM had increased ADG (0.71 vs. 0.68 ± 0.01 kg/d), regardless of the diet fed to progeny during the growth phases. Covariant analysis using ADG did not alter inferences about maternal or progeny diet effects on OC responses. Although 100% of progeny at 12 wk had histologically apparent OC lesions, only 3 of the 200 pigs examined at 24 wk had gross lesions of sufficient severity to potentially result in clinically apparent disease. Therefore, although some results imply that maternal and progeny CTM diets increased the size (12 wk) and severity (24 wk) of OC in 1 site (the femur), on the whole animal level, no evidence of lameness was noted.

Dietary organic zinc attenuates heat stress-induced changes in pig intestinal integrity and metabolism.

Dietary zinc (inorganic and organic or zinc AA complex forms) is essential for normal intestinal barrier function and regeneration of intestinal epithelium. Given that heat stress (HS) exposure can negatively affect intestinal integrity and caloric intake, possible nutritional mitigation strategies are needed to improve health, performance, and well-being. Therefore, our objective was to evaluate 2 dietary zinc sources and reduced caloric intake on intestinal integrity in growing pigs subjected to 12 h of HS. A total of 36 pigs were fed 1 of 2 diets: 1) a control diet (CON; 120 mg/kg of zinc from zinc sulfate) or 2) 60 mg/kg from zinc sulfate and 60 mg/kg from zinc AA complex (ZnAA). After 17 d, the CON pigs were then exposed to thermal neutral (TN) conditions with ad libitum intake (TN-CON), HS (37°C) with ad libitum intake (HS-CON), or pair-fed to HS intake under TN conditions (PFTN); the ZnAA pigs were exposed to only HS (HS-ZnAA). All pigs were sacrificed after 12 h of environmental exposure, and blood and tissue bioenergetics stress markers and ex vivo ileum and colon integrity were assessed. Compared with TN-CON, HS significantly ( < 0.05) increased rectal temperatures and respiration rates. Ileum villus and crypt morphology was reduced by both pair-feeding and HS. Both PFTN and HS-CON pigs also had reduced ileum integrity (dextran flux and transepithelial resistance) compared with the TN-CON pigs. However, ZnAA tended to mitigate the HS-induced changes in ileum integrity. Ileum mucin 2 protein abundance was increased due to HS and pair-feeding. Colonic integrity did not differ due to HS or PFTN treatments. Compared with the HS-CON, HS-ZnAA pigs tended to have reduced blood endotoxin concentrations. In conclusion, HS and reduced feed intake compromised intestinal integrity in pigs, and zinc AA complex source mitigates some of these negative effects.

Effect of feeding peroxidized dried distillers grains with solubles to sows and progeny on growth performance and metabolic oxidative status of nursery pigs.

This experiment evaluated the effects of including peroxidized corn dried distillers grains with solubles (DDGS) in diets for sows and nursery pigs on growth performance, vitamin E (VE), and Se status, and the incidence of mulberry heart disease (MHD) of nursery pigs. Sows (n = 12) were fed corn-soybean meal diets (C-SBM) or C-SBM diets with DDGS (40% and 20% in gestation and lactation, respectively) for 3 parities. In the third parity, 108 weaned pigs (BW = 6.6 ± 0.36 kg) were blocked by BW within litter, assigned to pens (2 pigs/pen; 5 and 4 pens per litter for groups 1 and 2, respectively), and pens were assigned 1 of 3 nursery diets: 1) corn-soybean meal (CON), 2) 30% peroxidized DDGS (Ox-D), and 3) 30% Ox-D with 5 × NRC (1998) level of VE (Ox-D+5VE) for 7 wk, in a 2 × 3 factorial arrangement of sow and nursery diets (n = 9 pens/treatment). The peroxidized DDGS source in nursery diets contained concentrations of thiobarbituric acid reactive substances (TBARS) and peroxide values that were 25 and 27 times greater than a reference corn sample. Sow colostrum, milk, and serum, as well as pig serum and liver samples, were analyzed for α-tocopherol and Se concentrations. Pig serum was analyzed for glutathione peroxidase activity (GPx), TBARS, and sulfur-containing AA (SAA). Pig hearts were evaluated for gross and histopathological lesions indicative of MHD, but none were detected. Pigs from sows fed DDGS tended to have reduced (P = 0.07) VE in serum during lactation and reduced VE at weaning (P < 0.01; 5.6 vs. 6.7 ± 0.1 µg/mL) compared with pigs from sows fed C-SBM. Inclusion of DDGS in sow diets reduced the VE status of pigs during lactation, but not in the nursery when MHD can be a concern. Pigs fed Ox-D+5VE (P = 0.08) tended to have, and those fed Ox-D (P = 0.04) had greater ADFI than pigs fed CON, but ADG was not affected (P > 0.1) by nursery diet. Feeding Ox-D or Ox-D+5VE increased (P < 0.05) serum α-tocopherol compared with CON (2.5, 2.8, and 3.4 ± 0.09 µg/mL, respectively), but TBARS and GPx were not affected by nursery diet. Serum concentration of SAA was 40% to 50% greater (P < 0.01) for pigs fed Ox-D or Ox-D+5VE compared with those fed C-SBM, which was likely due to greater (P < 0.01) SAA intake for pigs fed Ox-D. The antioxidant properties of SAA may have spared VE and Se and masked any effect of Ox-D on metabolic oxidation status. Therefore, increasing the dietary VE concentration was unnecessary in nursery diets containing Ox-D.

Effects of supplemental zinc amino acid complex on gut integrity in heat-stressed growing pigs.

Heat stress (HS) jeopardizes livestock health and productivity and both may in part be mediated by reduced intestinal integrity. Dietary zinc improves a variety of bowel diseases, which are characterized by increased intestinal permeability. Study objectives were to evaluate the effects of supplemental zinc amino acid complex (ZnAA) on intestinal integrity in heat-stressed growing pigs. Crossbred gilts (43±6 kg BW) were ad libitum fed one of three diets: (1) control (ZnC; 120 ppm Zn as ZnSO4; n=13), (2) control+100 ppm Zn as ZnAA (Zn220; containing a total of 220 ppm Zn; n=14), and (3) control+200 ppm Zn as ZnAA (Zn320; containing a total of 320 ppm Zn; n=16). After 25 days on their respective diets, all pigs were exposed to constant HS conditions (36°C, ∼50% humidity) for either 1 or 7 days. At the end of the environmental exposure, pigs were euthanized and blood and intestinal tissues were harvested immediately after sacrifice. As expected, HS increased rectal temperature (P⩽0.01; 40.23°C v. 38.93°C) and respiratory rate (P⩽0.01; 113 v. 36 bpm). Pigs receiving ZnAA tended to have increased rectal temperature (P=0.07; +0.27°C) compared with ZnC-fed pigs. HS markedly reduced feed intake (FI; P⩽0.01; 59%) and caused BW loss (2.10 kg), but neither variable was affected by dietary treatment. Fresh intestinal segments were assessed ex vivo for intestinal integrity. As HS progressed from days 1 to 7, both ileal and colonic transepithelial electrical resistance (TER) decreased (P⩽0.05; 34% and 22%, respectively). This was mirrored by an increase in ileal and colonic permeability to the macromolecule dextran (P⩽0.01; 13- and 56-fold, respectively), and increased colonic lipopolysaccharide permeability (P⩽0.05; threefold) with time. There was a quadratic response (P⩽0.05) to increasing ZnAA on ileal TER, as it was improved (P⩽0.05; 56%) in Zn220-fed pigs compared with ZnC. This study demonstrates that HS progressively compromises the intestinal barrier and supplementing ZnAA at the appropriate dose can improve aspects of small intestinal integrity during severe HS.

Evaluation of Actinobacillus pleuropneumoniae diagnostic tests using samples derived from experimentally infected pigs.

New serological tests have recently been introduced for Actinobacillus pleuropneumoniae diagnosis. No information is currently available on how these tests compare regarding the detection of antibodies from subclinically infected pigs. To answer this question, 80 pigs were randomly assigned to experimental groups infected with A. pleuropneumoniae serovars 1, 3, 5, 7, 10, 12, 15 and a non-inoculated control group. Blood samples and oropharyngeal swabs were collected prior to infection and for 7 consecutive weeks thereafter. Serum samples were tested using the Swinecheck(®) APP ELISA and the Multi-APP ELISA (University of Montreal). All pigs were euthanized at 49 days post-inoculation. Tonsil and lung samples were cultured for isolation and tested by PCR. The Multi-APP ELISA detected seroconversion 1 week earlier than the Swinecheck(®) APP ELISA with the earliest seroconversion detected at 1 week post-infection (serovar 10) and the latest at 3 weeks post-infection (serovar 1). Seroconversion at day 49 was serovar-dependent and varied from 4 (44%) positives detected in the serovar 10 group to 9 positives (100%) detected in the serovar 15 group. Thirty-one pigs were serologically positive for A. pleuropneumoniae at 49 days post-infection and only 15 still carried A. pleuropneumoniae on their tonsils based on PCR results. No cross-reactions were observed when serum samples were cross-tested using the Swinecheck(®) APP ELISA. A. pleuropneumoniae was successfully isolated from the lung of 2 pigs that developed pleuropneumonia, but was not isolated from tonsils due to heavy contamination by the resident flora. This study offers a comprehensive evaluation of the diagnostic tools currently available for detection of A. pleuropneumoniae subclinical infection.

Monitoring of porcine reproductive and respiratory syndrome virus infection in boars.

A major concern exists on transmission of porcine reproductive and respiratory syndrome virus (PRRSV) via semen and effect of vaccination on PRRSV shedding in semen. Recent reports suggest that the virus can be transmitted by semen from boars infected experimentally or from natural sources. Seminal shedding, viremia, and changes in semen quality in boars with or without vaccination were examined. Nine boars were divided into three groups (three boars/group). Group I boars were vaccinated with 2 ml of RespPRRS vaccine (NOBL Laboratory) intramusculary and groups II and III were non-vaccinated. At 28 post-vaccination study days, group I and group II boars were challenged with virulent PRRSV VR-2332 at 2 ml of 10(4.0) TCID50 per boar intranasally. Group III served as non-vaccinated and non-challenged control. Semen and serum samples were collected from -9 pre-vaccination study days to 85 post-challenge study days and tested for the presence of PRRSV by virus isolation and reverse transcription-nested polymerase chain reaction (RT-nPCR). Prior to detection of PRRSV RNA from samples, conditions for RT-nPCR were optimized. Two primer sets, an external and an internal, were selected for RT-nPCR. The first round of PCR using an external primer set could detect 10 TCID50 of PRRSV/reaction. However, nested PCR could detect as little as 0.01 TCID50 of PRRSV/reaction. PRRS vaccine virus was not isolated from vaccinated pigs, but the vaccine virus RNA was detected from three boars, at day 6 to 15, 9 to 12, and 15 to 21 post-vaccination by RT-nPCR. Following challenge, two of non-vaccinated/challenged boars shed virus into semen up to 50 and 57 days post-challenge, respectively. The group I vaccinated boars did not shed virus into semen after challenge. The non-vaccinated/challenged group featured sperm abnormalities in the form of significantly increased incidence of proximal droplets and abnormal tails at 36-50 days post-challenge. The latter defect was observed to increase similarly in vaccinated/challenged boars as well.

Immune response and persistence of the porcine reproductive and respiratory syndrome virus in infected pigs and farm units.

The kinetics of the serum antibody response to porcine reproductive and respiratory syndrome (PRRS) virus and the persistence of the virus after infection were determined in experimentally and naturally infected pigs. In an experimental study, four specific pathogen free (SPF) sows were infected with a French strain of PRRS virus at 90 days of gestation, and their piglets (the test piglets) were monitored for 29 weeks from birth. In one litter, antibodies against PRRS virus were absent before the piglets had ingested colostrum. Four days after birth, passive antibodies were present in the serum of these piglets, but they had disappeared by three weeks (just before weaning) when clinical signs were observed in a minority of the pigs. In a second litter, most of the piglets had no detectable antibodies until they were four weeks old, and clinical signs were observed during their second week of life. By eight weeks, antibodies were detected in all the pigs, and they persisted until observations ceased at 29 weeks. Two groups of three SPF pigs were placed in direct contact with the test piglets when they were four weeks old and a group of five SPF pigs was placed in indirect contact when they were 13 weeks old. The first two groups showed clinical signs and seroconverted but the third group did not. At 22 weeks old, two of the test piglets were subjected to movement stress and were given exogenous corticosteroids, after which the in-contact SPF pigs developed clinical signs and seroconverted.(ABSTRACT TRUNCATED AT 250 WORDS)

Histochemical morphologic features of growth cartilages in long bones of pigs of various ages.

Growth cartilages were obtained from humeri, femora, and ulnae of 31 pigs between 1 and 169 days old. On the basis of stain uptake and distribution, distinct layers were identified in articular-epiphyseal cartilage complexes and growth plates. The laminated appearance was dependent on stain uptake by territorial and interterritorial matrices and was more distinct in pigs greater than 15 days old. There was morphologic heterogeneity, which probably represented a functional heterogeneity, among chondrocytes in all layers and zones of both types of growth cartilage. The laminar appearance of growth cartilages and the distribution of different types of cells were similar for all pigs in each age category and for all sites.

Angiomicrographic investigation of the vessels associated with physes in young pigs.

There is little information available relating to the vasculature of physes of pigs, hence the object of the present study was to establish the distribution of blood vessels in normal physes of pigs at one and 15 days old. By the use of an angiomicrographic technique it was possible to demonstrate that vessels were in two main categories; first, those which entered the physis from the epiphysis and terminated, or branched and then terminated half to two thirds of the distance into the depth of the physis; second, vessels which crossed the full depth of the physis. Since vessels that cross the physis from epiphysis to metaphysis were a frequent feature of normal physes they do not seem to be a congenital defect which predisposes to the development of dyschondroplasias in young pigs.

Dyschondroplasias of growth cartilages (osteochondrosis) in crossbred commercial pigs at one and 15 days of age: radiological, angiomicrographical and histological findings.

The age of onset and morphology of the earliest lesions of dyschondroplasias in pigs have not been established. Bones and growth cartilages from pigs were examined for the presence of lesions using radiological, angiomicrographical and histological techniques. Lesions were in 10 of 11 pigs at 15 days of age and 12 of 21 pigs at one day of age, indicating that the condition was congenital. The simplest and apparently earliest lesion was an area of persistent hypertrophied chondrocytes and matrix which extended from the articular-epiphyseal complex or physis into the epiphysis or metaphysis, respectively. Since the prevalence of lesions was high it was considered that the dyschondroplasia may be part of the usual growth pattern of cartilages in contemporary pigs.