Adsorption of colostral antibodies against classical swine fever, persistence of maternal antibodies, and effect on response to vaccination in baby pigs.

OBJECTIVE: To determine kinetics of antibody absorption, persistence of antibody concentrations, and influence of titers on vaccination of baby pigs with a vaccine against classical swine fever (CSF). ANIMALS: 15 sows and their litters. PROCEDURE: Farrowings were supervised. Initial time of suckling was recorded. In the first experiment, blood samples were collected at farrowing, 2 and 4 hours after suckling, and hourly until 10 hours after initial suckling. Samples were assayed for CSF antibodies, using a serum neutralizing (SN) test. A second experiment included 33 baby pigs vaccinated as follows: 10 prior to ingestion of colostrum, 18 between 1 and 4 hours after ingestion of colostrum, and 5 at 12 hours after ingestion of colostrum. Fourteen pigs were vaccinated when 7 weeks old, and 15 pigs were not vaccinated. At 10 weeks of age, pigs were challenge-exposed with virulent CSF virus. Blood samples were collected and assayed for CSF antibodies and p125 antigen and p125 antibodies. RESULTS: CSF antibodies were detected in pigs beginning 2 hours after suckling. Colostral antibodies persisted for > 7 weeks (half-life, 79 days). Vaccination of pigs before suckling provided effective protection from severe disease after challenge-exposure. However, vaccination of neonates with antibody titers was not effective, because 19 of 23 (82%) pigs succumbed after challenge-exposure. All pigs vaccinated when 7 weeks old resisted challenge-exposure, whereas all unvaccinated control pigs succumbed. CONCLUSIONS AND CLINICAL RELEVANCE: Vaccination before ingestion of colostrum conferred good protection against CSF in baby pigs. Vaccination of 7-week-old pigs that had decreasing concentrations of passively acquired antibodies was efficacious.     

Studies on the age resistance of swine to group A rotavirus infection.

To determine whether swine become naturally age resistant to group A rotavirus infection, colostrum-deprived, rotavirus-naive newborn pigs that were raised in isolation (n = 34) were studied. Neonatal pigs and pigs 1, 2, 4, 6, 8, 10, and 12 weeks of age were inoculated orally with group A porcine rotavirus or mock inoculum and euthanatized at 24, 31, or 48 hours post-infection. Nine sections of small intestine, cecum, and colon were harvested and immunohistochemically examined for evidence of rotavirus replication within enterocytes. Infectivity was semiquantified by intestinal segment, and a composite score was obtained for each animal. In pigs inoculated at 1 week of age, enterocyte infection was mild and scattered; all other pigs became infected regardless of age or region of intestine, and older animals that became infected had infectivity scores similar to those of younger animals. In a second more limited study, pigs raised in the same isolation environment (n = 11) but previously exposed to virus and demonstrating rotavirus serum antibody had a much lower degree of enterocyte infection at 8, 10, and 12 weeks of age (2, 4, and 6 weeks, respectively, after initial exposure to virus). Age resistance to clinical rotavirus disease in swine is due to factors other than an age-dependent development of resistance of enterocytes to infection, at least through 12 weeks of age.     

Age-dependent occurrence of the intestinal ciliate Balantidium coli in pigs at a Danish research farm

A cross sectional study of the prevalence and intensity of Balantidium coli in pigs was carried out on a Danish research farm. The prevalence of B. coli infection increased from 57% in suckling piglets to 100% in most pig groups > or = 4 weeks old. The mean number of cysts per gram faeces (CPG) of pigs aged 12 weeks and younger were < or = 206, whereas pigs aged 28 weeks and > 52 weeks had significantly higher counts of > or = 865 CPG. Although some lactating sows had very high CPG's, no significant differences in CPG could be detected between the intensities of pregnant sows, lactating sows and empty and dry sows. No human cases of B. coli infection have been published in Denmark though it is zoonotic.     

Effect of weaning age and commingling after the nursery phase of pigs in a wean-to-finish facility on growth, and humoral and behavioral indicators of well-being

Pigs from one farrowing group in which gilts were bred to farrow pigs that would be either 14 or 21 d of age at weaning, were divided into older and younger age groups (108 pigs per group) and penned 12 pigs per pen in a wean-to-finish facility. At the end of the nursery phase, half the pigs in each age group were removed, rerandomized, and commingled for the finishing phase. The other half remained in their original pens. Pigs were fed common Phase 1 (d 0 to 14) and Phase 2 (d 14 to 35) nursery diets, and a common 4-phase program diet during growing/finishing, with transitions at 45, 68, and 90 kg of BW. The study ended when the lightest weight block averaged 107 kg. Blood was obtained on d 0, 2, 10, 27, 37, 44, and 65 after weaning to determine leukocyte concentrations. In addition, behavior was monitored during the nursery period at weaning (d 0), on d 7, 14, and 27 after weaning, and during the growing/finishing phase on d 35 (after commingling following the nursery phase), 38, 44, and 65 after weaning. Older pigs were heavier (P < 0.001) throughout the nursery period, and the BW difference between younger and older pigs increased from 2 to 6.5 kg at the start and end of the nursery period, respectively. Older pigs had a greater concentration of white blood cells (P < 0.05) and lymphocytes (P < 0.10) on d 0, 2, and 10 after weaning than younger pigs. Younger pigs spent less (P < 0.05) time resting on the day of weaning, and more (P < 0.05) time active during the overall nursery phase. During Phase 3 and in the overall finishing phase, younger pigs had greater (P < 0.01) ADG and G:F than older pigs. Moreover, during Phase 3, ADFI (as fed) decreased (P < 0.05) when older pigs were commingled compared with older pigs that were not commingled. There was no difference in ADFI of younger pigs, regardless of commingling (interaction; P < 0.10). Results of this study indicate that weaning age affects growth performance in a wean-to-finish facility, as well as behavioral and immunological responses to weaning and commingling after the nursery phase. Management strategies should be further explored to optimize these benefits without the detrimental effects on health observed during the nursery period in this study.     

Lesions of transmissible gastroenteritis virus infection in experimentally inoculated pigs suckling immunized sows

Intestinal lesions of transmissible gastroenteritis (TGE) virus infection in conventionally reared pigs suckling either nonvaccinated, vaccinated, or previously infected sows were studied by scanning electron microscopy, light microscopy, and immunofluorescent microscopy for TGE viral antigen. Pigs were inoculated with virulent TGE virus when they were 5 or 21 days old and were euthanatized shortly after the onset of diarrhea or 96 hours after inoculation if no diarrhea developed. Pigs inoculated when they were either 5 or 21 days old and suckling nonvaccinated sows developed severe lesions, including swelling and necrosis of enterocytes and severe villus atrophy. Pigs inoculated when they were 5 days old and suckling sows vaccinated with attenuated vaccines developed less-severe villus atrophy, and those suckling sows immunized by exposure to nonattenuated TGE virus developed moderate or no villus atrophy. Pigs inoculated when they were 21 days old and suckling sows vaccinated with attenuated vaccines had severe villus atrophy, whereas those suckling sows immunized by exposure to nonattenuated virus had more-moderate villus lesions. Villus atrophy was inhibited to various degrees in pigs suckling immunized sows, depending in part on the antibody titer in the colostrum and milk.     

Effect of recombinant DNA-derived bovine alpha-1 interferon on transmissible gastroenteritis virus infection in swine

Recombinant DNA-derived bovine interferon alpha 1-1 (BoIFN) inhibited replication of both vesicular stomatitis virus and transmissible gastroenteritis virus in cultures of swine testicular cells. Newborn pigs were orally inoculated with BoIFN and subsequently had interferon in their gastric contents and serum; however, interferon was found only occasionally in intestinal washings. Incubation of BoIFN with gastric contents from a newborn suckling pig did not affect antiviral activity, whereas intestinal (small intestine) contents from the same animal inactivated BoIFN within 1 minute. Beginning at 6 hours of age, newborn, colostrum-deprived pigs were given 1 mg of BoIFN orally every 12 hours. These pigs were not protected against challenge exposure to virulent transmissible gastroenteritis virus at 48 hours of age; disease and mortality were similar for these pigs and for control pigs not given BoIFN prior to challenge exposure. The BoIFN did not impair growth rate of pigs and did not cause obvious disease or lesions.     

The influence of age on the pharmacokinetics of aditoprim in pigs after intravenous and oral administration

Some pharmacokinetic parameters of aditoprim were determined in 3- and 6-month-old pigs. After intravenous administration of 5 mg/kg body weight, the mean total body clearance of the older pigs was smaller than that of the younger pigs. This difference was not reflected in the elimination half-life. After oral administration of 5 mg/kg body weight, the mean absorption rate constant was smaller and the mean absorption half-life was longer in the older pigs. The age-related changes in the pharmacokinetics of aditoprim were not sufficiently pronounced to suggest the necessity of modifying the oral dosage regimen in pigs of this age range. The favourable pharmacokinetics of aditoprim in pigs (large apparent volume of distribution, long elimination half-life and high bioavailability) may permit introduction of this drug into swine practice, after safety and residue depletion studies.     

Effects of pig age at market weight and magnesium supplementation through drinking water on pork quality

Thirty-two halothane-negative pigs (109 +/- 0.6 kg of BW) were used to determine the effect of pig age at marketing (and thus growth rate), and magnesium supplementation through drinking water, on pork quality. Two initial groups of 50 pigs that differed by 30 +/- 2 d of age were fed diets to meet or exceed nutrient requirements beginning at 28 kg of BW. Sixteen average, representative pigs were selected from each group to represent older, slow-growing pigs and younger, fast-growing pigs. For the duration of the study, pigs were individually penned, provided 2.7 kg of feed (0.12% Mg) daily, and allowed free access to water. After 7 d of adjustment, pigs were blocked by sex and BW and allotted to 0 or 900 mg of supplemental Mg/L as MgSO4 in drinking water for 2 d before slaughter. All 32 pigs were then transported (110 km) to a commercial abattoir on the same day and slaughtered 2.5 h after arrival. Longissimus and semimembranosus (SM) chops were packaged and stored to simulate display storage for fluid loss and Minolta color determinations at 0, 2, 4, 6, and 8 d. Two remaining sections of the LM were vacuum-packaged and stored at 4 degrees C for 25 or 50 d. Fast- (younger) and slow- (older) growing pigs differed by 27 +/- 0.3 d of age (153 and 180 +/- 0.3 d; P < 0.001) at similar BW (108 and 110 +/- 0.6 kg of BW; P = 0.13). Supplementation of Mg tended to increase plasma Mg concentration (24.1 vs. 21.8 +/- 0.8 ppm; P = 0.06) but did not affect Mg concentration in LM or SM. Fluid loss of displayed LM or SM, and purge loss, color, and oxidation of vacuum-packaged LM or SM were not affected by age or Mg (P > 0.10). Surface exudate of the SM from older pigs was lower than that of younger pigs (61 vs. 74 +/- 6 mg; P = 0.05) but was not different for the LM (P = 0.22). The LM from older pigs displayed for 4 and 8 d; P < 0.05) were less yellow (lower b*) than younger pigs. The SM from older pigs had lower lightness (L*) initially (47.9 vs. 49.5 +/- 0.4) and after 2 d (49.7 vs. 51.1 +/- 0.4), 6 d (52.1 vs. 53.7 +/- 0.4) and 8 d (54.5 vs. 55.9 +/- 0.4) of display storage. Younger pigs had greater oxidation of the LM than older pigs on d 8 of display (P < 0.01), and Mg decreased oxidation on d 8 within younger pigs (P < 0.05). Pork quality was improved in older pigs as indicated by less exudate, reduced yellowness of the LM, reduced paleness of the SM, and reduced oxidation of the LM. However, Mg supplementation through the water for 2 d did not affect pork quality of either older, slower growing pigs or younger, faster growing pigs.     

Exploratory field study on Mycoplasma hyopneumoniae infection in suckling pigs

The present study focused on Mycoplasma hyopneumoniae (M. hyopneumoniae) detection by nPCR in nasal swabs of 507 suckling pigs. These animals came from 69 sows (from 1 to 8 parity number) of a farrow-to-finish herd with Enzootic Pneumonia (EP) problems at finishing stages. At 1 and 3 weeks of age (still in the farrowing units), nasal swabs and blood samples were taken from all piglets. Moreover, from these 507 animals, 37 randomly selected pigs were necropsied at 3 weeks of age. From those necropsied pigs, M. hyopneumoniae presence was tested in bronchial and tonsillar swabs. At 1 week post-farrowing, blood samples from sows were collected and used to detect M. hyopneumoniae antibodies. From the 69 analysed sows, 19 (27.5%) were seropositive. Global percentage of pigs with M. hyopneumoniae detection in nasal swabs at 1 and 3 weeks of age was 1.5% (8 out of 507) and 3.8% (19 out of 507), respectively. From these nPCR positive pigs, 89% (24 out of 27) were seronegative and 11% were seropositive. From necropsied animals, the pathogen DNA was detected in two pigs at bronchus level and in another pig at tonsil. In this study, sow parity was not statistically related with sow seropositivity and piglet colonization. These results confirm that M. hyopneumoniae infection may be detected not only in nasal cavities of naturally infected suckling piglets but also at their low respiratory tract airways. Our results suggest that M. hyopneumoniae detection in lower and upper respiratory tract could be an indicator that respiratory problems associated to EP may start relatively early in the production system. In consequence, sow-to-piglet and/or piglet-to piglet transmission in farrowing barns should not be underestimated.     

Pharmacokinetics, inhibition of lymphoblast transformation, and toxicity of cyclosporine in clinically normal pigs

Pharmacokinetic variables were calculated from time-concentration data obtained after IV (10 mg/kg of body weight; n =9) and oral (12.5 mg/kg to group A [n = 3]; 25 mg/kg to group B [n = 3]; and 50 mg/kg to group C [n = 3] pigs) cyclosporine (formerly, cyclosporine A) administration. Resulting mean (+/- SD) pharmacokinetic variables were as follows: half life of distribution, 0.96 (+/- 0.7) hours; half life of elimination, 7.71 (+/- 2.6) hours; volume of distribution at steady state, 4.47 (+/- 2.22) L/kg; volume of the central compartment, 1.71 (+/- 0.78) L/kg; and systemic clearance, 8.95 (+/- 2.7) ml/kg/min. Oral bioavailability was: overall 57 (+/- 19) %; group A, 44 (+/- 11) %; group B, 78 (+/- 15) %; group C, 48 (+/- 6) %. Time to peak concentration was 3.55 (+/- 0.88) hours. During the 22 days of daily oral cyclosporine administration, blood 24-hour trough concentrations were: group A, 224.3 (+/- 78.4) ng/ml; group B, 640.7 (+/- 174.6) ng/ml; and group C, 2,344 (+/- 1,095) ng/ml. Lymphoblast transformation stimulation index was suppressed in all pigs except 1, which had a corresponding cyclosporine concentration of 92.4 ng/ml. Minimal, although statistically significant, decreases in serum albumin and magnesium concentrations and increases in serum creatinine and urea nitrogen concentrations were evident in pigs of some treatment groups. Histologic examination of necropsy specimens revealed mild hepatic necrosis (n = 1 pig), renal tubular dilatation (n = 5), and pulmonary inflammation (n = 2). Pigs given 25 and 50 mg of cyclosporine/kg failed to gain weight.     

A comparative efficacy test of 1 versus 2 doses of CIRCOQ PCV2 subunit vaccine against naturally occurring PCV2-type d in piglets with high maternally derived antibodies (MDAs) on a Vietnamese swine farm

The aim of this study was to evaluate the protective efficacy of the CIRCOQ porcine circovirus type 2 (PCV2) subunit vaccine in piglets with high maternally derived antibodies (MDAs) against disease caused by natural infection with PCV2d. A total of 130 weaned, 21-day-old healthy pigs was allocated into 3 trial groups. The signs of respiratory disorder were higher in unvaccinated pigs than in vaccinated pigs at 13 to 17 weeks old (P < 0.05), 18 to 22 weeks old (P < 0.001), and 23 to 27 weeks old (P < 0.01). The unvaccinated pigs had an early rate of dermatitis at 8 to 12 weeks old (10.0%), 13 to 17 weeks old (30.0%), 18 to 22 weeks old (46.7%), and 23 to 27 weeks old (33.3%), while there were no cases of dermatitis in vaccinated pigs. There was a significant difference (P < 0.05) in the mortality of pigs in the unvaccinated group and the 2-dosed vaccinated group. PCV2 viremia was detected in the blood and peaked at 105 days old in both unvaccinated pigs (Ct-adj = 8.40) and pigs vaccinated with 1 dose (Ct-adj = 6.37), while no detectable PCV2 virus was found in the blood of pigs vaccinated with 2 doses. At 77 and 105 days old, the PCV2 viremia load (Ct-adj) of unvaccinated pigs and those vaccinated with 1 dose was significantly higher (P < 0.05) than that of the 2-dosed vaccinated pigs. The body weight (BW), average weight gain (AWG), and average daily gain (ADG) in both groups of vaccinated pigs were significantly higher (P < 0.05) than those of unvaccinated pigs. The study vaccine was significantly efficacious in protecting vaccinated pigs against clinical symptoms, blood viral load, and mortality, as well as improving productivity, compared with unvaccinated pigs.     

Weight gains in rats of different ages after administration of insulin]

An experiment was made to examine the body weight gains after administration of deposit insulin (40 units per kg of live weight) in rats at the age of 1-12 days, 8-10 weeks and 18-20 weeks. The administration of insulin to suckling young (aged 11-12 days) did not influence the weight gains. Eight- to ten-week old rats showed a reduction and 18- to 20-week old rats showed a reduction and 18- to 20-week old rats an increase of weight gains in the course of the experiment.     

Leptospirosis in pigs: The effectiveness of streptomycin in stopping leptospiruria

A trial was conducted to assess the efficacy of a single intra-muscular injection of 25mg per kg of streptomycin in stopping leptospiruria in growing pigs exposed to a natural infection.

The investigation involved 54 pigs, 10–12 weeks old, that were free of serological evidence of infection with serotypes pomona or tarassovi at the start of the trial. The animals were kept in pens in a finishing house through which flowed effluent from other pens containing infected pigs. Urine samples were collected from each pig three times weekly until it was slaughtered for bacon at 20–24 weeks old.

Leptospiruria was first detected between 16 and 74 days after exposure. Twenty-one of 37 pigs which showed leptospiruria were injected with streptomycin. Leptospirae were detected in 11 of 185 (5.9%) subsequent urine samples from these 21 treated animals and serotype pomona was cultured from the kidney of 1 of the 10 animals that were examined from this group at slaughter.

Following the initial detection of leptospiruria in the 16 un-treated pigs, 179 of 211 (84.8%) subsequent urine samples con-tained leptospirae, which were also cultured from the kidneys of 4 out of 11 of these animals.     

Colostral transfer of Clostridium perfringens type C beta antitoxin in swine

Nine bred gilts were vaccinated with 2 doses of a Clostridium perfringens type C toxoid at a 5-week interval. Time of vaccination during gestation differed among the gilts. Clostridium perfringens beta antitoxin in colostral samples and in serum samples was titrated in mice. Blood was collected from 2 to 5 neonatal pigs from each dam (total = 32 pigs) when the pigs were 36 to 48 hours old. Antitoxin titers in colostrum were 123 to 4.5 IU/ml, indicating considerable variation in individual responses of the gilts to toxoid. Serum titers of neonatal pigs reflected colostrum titers of their dams. This colostrum-to-serum titer correlation was essentially a straight-line fit by least-squares linear regression analysis, establishing a direct proportional relationship between colostrum titers and serum titers of neonatal pigs. In the dams, a correlation was not found between colostral titers and serum titers of blood samples collected 2 weeks after collection of colostrum.     

Fasting plasma hormones and metabolites in feral and domestic newborn pigs

Newborn Yorkshire and Ossabaw (feral) pigs were examined under thermoneutral conditions to determine whether survival rate during fasting differs between these breeds and whether any blood-borne factors are associated with improved survival. Newborn pigs were removed from the sow before suckling. Body composition was determined on 10 newborn Ossabaw and 12 newborn Yorkshire pigs. Another group of animals (eight Ossabaw, 12 Yorkshire) was fasted for 72 hr, with blood samples drawn at birth and 12 and 24 hr into fasting. Glucose, free fatty acid (FFA), growth hormone (GH), insulin, thyroxine (T4), triiodothyronine (T3), cortisol and glucagon concentrations were measured in plasma of fasted pigs. Concentrations of carcass lipid, dry matter and ash were higher in newborn Ossabaw pigs than in newborn Yorkshire pigs. Survival through 72 hr of fasting was lower among Yorkshire pigs. Yorkshire and Ossabaw pigs had similar concentrations of metabolites and hormones at birth, with the exceptions of lower plasma GH and higher T3 concentrations in Ossabaw pigs. Higher plasma T3 concentrations would indicate a greater potential for fatty acid oxidation. During fasting, Ossabaw pigs had lower plasma GH and T4 concentrations and higher glucagon and FFA concentrations. Increased survival among newborn Ossabaw pigs may have been due to increased availability of FFA during fasting, and to a greater potential for gluconeogenesis through increased oxidation of fatty acids and higher plasma glucagon concentrations. This would suggest that maternal treatments that would increase storage of fat and(or) increase the capacity for oxidation of fat in utero would improve survival of newborn pigs.     

The effect of stress on blood levels of vitamin A and E in piglets

In five trials with 99 suckling or weaned piglets, the effects of the increased adrenocortical function, caused by cold, weaning from the sow or fasting or by stimulation with exogenous adrenocorticotrophic hormone (ACTH) were studied as exerted on vitamin A and vitamin E concentrations in the blood serum. Three hours after an exposure of three-day and four-day piglets to the temperature of 8-12 degrees C, a small drop of the concentrations of both vitamins occurred. In four-week weanling piglets a decrease in vitamin E concentration was observed in two days, the trend being slight in vitamin A concentration. At the same time some sibs were left fasting, which considerably reduced the concentrations of both vitamins. The situation was similar in two hours after ACTH administration to suckling piglets, however the difference was insignificant in vitamin E concentrations. In seventeen hours elapsing from two administrations of the adrenocorticotrophic hormone (ACTH) when the increased secretion of corticosteroids was fading out, only the vitamin A concentration in suckling piglets was found to drop. The response in weanling piglets was negligible. The suppressive effects of stress on vitamin A concentrations were usually observed when the levels of circulating corticosteroids were high or in the period immediately following this status. The changes in nutrition after early weaning exert large negative effects on vitamin E concentrations in the blood serum. The differences in the response of the organism to the two vitamins may be due to various types of transport mechanisms in the blood circulation. The specific effects of stress factors are mentioned.     

Therapeutic effects of various concentrations of lincomycin in drinking water on experimentally transmitted swine dysentery

Three experimental studies were conducted in 232 growing pigs (8 to 12 weeks old) to evaluate the therapeutic effects of various concentrations of lincomycin in drinking water, against swine dysentery experimentally transmitted, by oral inoculation or by contact-commingling exposure. Four or 5 concentrations of lincomycin were used in each experiment (132, 66, 33, 16.5 or 0.0 mg/L of drinking water). Medication was initiated 7 to days after exposure and was continued for 6 to 10 days. Both methods of exposure were capable of transmitting the disease successfully. A more marked dose response was noticed in pigs inoculated orally than in pigs that were exposed by contact. All concentrations of lincomycin were effective for the treatment of swine dysentery by oral or by contact exposure. At the smaller concentration of 16.5 mg/L of drinking water, lincomycin was less effective for treating the disease than it was at greater concentrations. The suggested optimal concentration was 33 mg of lincomycin/L of drinking water for the treatment of swine dysentery.     

Shedding pattern and serological profile of porcine circovirus type 2 infection in cesarean-derived, colostrum-deprived and farm-raised pigs

Six 5-week-old porcine circovirus type 2 (PCV2)-free, cesarean-derived, colostrums-deprived (CDCD) pigs were inoculated intranasally with 10(6) TCID(50) of PCV2. Four CDCD pigs were untreated cohabitants. Forty farm-raised pigs from two PCV2-contaminated herds were randomly selected for PCV2 trace investigations. Blood, nasal, oropharyngeal and fecal samples were collected from all tested pigs weekly. The PCV2 DNA shed at 6-11 and 7-12 weeks of age for PCV2-inoculated pigs and cohabitants, respectively. All the CDCD pigs exhibited seroconversion after PCV2 exposure. In the farm-raised animals, PCV2 shed at 9-15 weeks of age and seroconversion started at 11 weeks of age. Collectively, the pigs had a prolonged PCV2 shedding period following viral exposure, and growing pigs were the source of horizontal PCV2 transmission in PCV2-infected herds.     

Variability of neutrophil and pulmonary alveolar macrophage function in swine

Neutrophils and alveolar macrophages are essential defence mechanisms against bacterial infection of the lung. The purpose of this study was to evaluate the variability of a panel of neutrophil and alveolar macrophage function assays in swine, and to determine if the function of these leukocytes differed at various stages of production. Measured neutrophil functions included chemotaxis, phagocytosis, oxidative burst, and degranulation. Phagocytosis and oxidative burst were measured in alveolar macrophages isolated from bronchoalveolar lavage fluid (BALF). Both neutrophil and alveolar macrophage functions were highly variable from day-to-day and between pigs. Individual pigs did not have consistently high or low neutrophil and macrophage responses over time when compared to their cohorts. Older grower-finisher pigs had significantly greater neutrophil oxidative burst responses than younger suckling and weaner pigs (P < 0.001). Similarly, alveolar macrophages from suckling and early weaner pigs less than 40 days of age had significantly lower oxidative burst responses than those from older pigs (P = 0.02). Age-related variation in phagocytosis, chemotaxis, or granule secretion were not detected. These results establish baseline data for individual and age-related variation in swine leukocyte function, and form a basis for further evaluation of the contribution of non-infectious factors to development of the porcine respiratory disease complex.     

Postnatal changes of plasma amino acids in suckling pigs

Amino acids, ammonia, urea, orotate, and nitrate plus nitrite (stable oxidation products of nitric oxide) were determined in plasma of 1- to 21-d-old suckling pigs. Jugular venous blood samples were obtained from pigs at 1, 3, 7, 14, and 21 d of age for analysis of plasma amino acids and metabolites by HPLC and enzymatic methods. Plasma concentrations of arginine and its immediate precursors (citrulline and ornithine) decreased (P < 0.01) progressively (20 to 41%) with increasing age from 3 to 14 d. Plasma concentrations of glutamine declined (P < 0.01) progressively (10 to 31%) during the 1st wk of life. Plasma concentrations of branched-chain amino acids, threonine, and alanine decreased (P < 0.01) (5 to 12%) in 14- and 21-d-old pigs, compared with 1- and 3-d-old pigs. There were no postnatal changes (P > 0.05) in plasma concentrations of other amino acids. Plasma concentrations of ammonia increased (P < 0.01) by 18 and 46%, whereas those of nitrate plus nitrite decreased (P < 0.01) by 16 and 29%, in 7- and 14-d-old pigs, respectively, compared with 1- to 3-d-old pigs. Because arginine plays a crucial role in ammonia detoxification via the hepatic urea cycle and is the physiological substrate for nitric oxide synthesis, our results of the decreased plasma concentrations of arginine and nitrate plus nitrite, as well as the increased plasma ammonia concentration, indicate a hitherto unrecognized deficiency of arginine in 7- to 21-d-old suckling pigs. Arginine is an essential amino acid for piglets and has a great potential to enhance neonatal growth; therefore, further studies are necessary to elucidate the mechanism responsible for arginine deficiency in sow-reared piglets and to identify hormonal and metabolic means for improving neonatal arginine nutrition and growth.