Evaluation of immune system function in neonatal pigs born vaginally or by Cesarean section

Full term crossbred sows were selected to study the interaction of the immune system, hypothalamus-pituitary-adrenal axis, and growth in pigs born by Cesarean section (c-section; n=4 sows) or vaginal birth (n=4 sows). Gestation length and birth weight did not differ between vaginal birth and c-section pigs (P=0.34 and 0.62, respectively). Blood and tissue samples were collected from 44 pigs at birth. Forty-five pigs were weaned at 13 d. On d 14, pigs received an i.p. injection of lipopolysaccaride (LPS; 150 microg/kg) or saline at min 0, and blood samples were collected at -20, -10, 0, 5, 10, 20, 40, 60, 90, and 120 min. Vaginal birth pigs had 21% greater average daily gain than c-section pigs on d 14 (P<0.01). Basal serum concentrations of adrenocorticotrophin (ACTH) and cortisol were greater in c-section than vaginal birth pigs at birth (P<0.01) but were not different at 14 d (P=0.99 and 0.80, respectively). LPS increased serum concentrations of ACTH, cortisol, interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha; P<0.01) but the response was not different between c-section and vaginal birth (P>0.22). Basal serum concentrations of TNF-alpha tended to be greater in c-section vs vaginal birth pigs at 14 d (P=0.0967); however, basal serum concentrations of IFN-gamma tended to be lower in c-section pigs vs vaginal birth pigs at 14 d (P=0.0787). Expression of interleukin (IL)-6, IL-6 receptor, IL-1beta, and TNF-alpha mRNA did not differ between vaginal birth and c-section pigs but changed in an age and tissue dependent manner. Thus, reduced growth rate of c-section pigs is associated with altered immune system function.     

Birth by caesarian section alters postnatal function of the hypothalamic-pituitary-adrenal axis in young pigs

Eight crossbred sows were selected for the present study (n = 4 vaginal delivery and n = 4 Caesarian section [C-section]). Gestation length did not differ between vaginal delivery and C-section pigs (113.6 +/- .1 and 113.2 +/- .3 d, respectively; P > .16). Blood and tissue samples from 38 pigs were collected at birth. All remaining pigs were sustained with vaginal-delivery sows until 2 wk of age (n = 39). At 2 wk of age, remaining pigs were catheterized for blood sample collection to assess pituitary-adrenal responsiveness to an injection of corticotropin-releasing hormone (CRH; 10 microg/kg). Blood samples were collected at -30, -15, 0, 5, 10, 20, 40, 60, and 90 min; pigs received CRH or saline at time 0. Pigs were killed and tissue samples were collected immediately following the last blood sample. Serum concentrations of ACTH and cortisol (CS) were measured. Total RNA was isolated from the pituitary and adrenal glands to evaluate gene expression for mRNA specific for pro-opiomelanocortin (POMC) and for the ACTH receptor. Centrifuged clot:blood ratio was reduced in the C-section pigs at birth (P < .001) and at 2 wk of age (P < .043), compared with the vaginally delivered pigs. Basal serum concentration of ACTH was greater in C-section than in vaginally delivered pigs at birth (P = .01) but did not differ at 2 wk of age (P = .42). Basal serum concentration of CS was not different at birth (P = .86) but was greater in C-section pigs than in vaginally delivered pigs at 2 wk of age (P < .04). Serum concentration of ACTH was not different (P > .99) between the two groups of pigs following the CRH challenge. However, serum concentration of CS was greater (P < .05) in C-section pigs following the CRH challenge. Expression of ACTH receptor mRNA tended to be greater in C-section pigs at birth (P < .063) and at 2 wk of age (P < .016). There was no difference in POMC mRNA between treatments (P > .73); however, there was a developmental increase (P < .001) from birth to 2 wk of age. These data indicate that the birth process plays an important role in postnatal function of the hypothalamic-pituitary-adrenal axis in young pigs.     

Evaluation of lung function in pigs either experimentally or naturally infected with Chlamydiaceae

This study evaluated the influence of chlamydial infections on lung function in conventionally raised pigs. Eight pigs aged 39-44 days were included in an aerogeneous challenge model (4 were exposed to Chlamydia suis; 4 served as controls). Nineteen pigs aged 5-27 weeks without clinical symptoms (but partly PCR-positive for chlamydial species) were examined over 6 months. For lung function testing, impulse oscillometry was used. In total, all 27 pigs underwent 465 lung function tests. Variables of ventilation (respiratory rate, tidal volume, minute volume), respiratory impedance (expressed as resistance and reactance within the frequency range 3-15 Hz), and model derived resistance of proximal and distal airways were measured. Experimental exposure to C. suis significantly affected lung function. Early distal airway obstruction (3-5 days after infection) was followed by an obstruction of proximal airways (7 days after infection). The breathing pattern was significantly changed (decreased tidal volume; increased respiratory rate). In symptom-free pigs having a naturally acquired presence of different chlamydial species in the respiratory system, no deterioration in lung function could be determined up to the age of 6 months. In conclusion, the consequences of respiratory chlamydial infections appear to vary from clinical inapparence to severe respiratory distress.     

Evaluation of lung function in pigs either experimentally or naturally infected with Chlamydiaceae

This study evaluated the influence of chlamydial infections on lung function in conventionally raised pigs. Eight pigs aged 39–44 days were included in an aerogeneous challenge model (4 were exposed to Chlamydia suis; 4 served as controls). Nineteen pigs aged 5–27 weeks without clinical symptoms (but partly PCR-positive for chlamydial species) were examined over 6 months. For lung function testing, impulse oscillometry was used. In total, all 27 pigs underwent 465 lung function tests. Variables of ventilation (respiratory rate, tidal volume, minute volume), respiratory impedance (expressed as resistance and reactance within the frequency range 3–15 Hz), and model derived resistance of proximal and distal airways were measured. Experimental exposure to C. suis significantly affected lung function. Early distal airway obstruction (3–5 days after infection) was followed by an obstruction of proximal airways (7 days after infection). The breathing pattern was significantly changed (decreased tidal volume; increased respiratory rate). In symptom-free pigs having a naturally acquired presence of different chlamydial species in the respiratory system, no deterioration in lung function could be determined up to the age of 6 months. In conclusion, the consequences of respiratory chlamydial infections appear to vary from clinical inapparence to severe respiratory distress.     

The role of the somatotrophic axis in the metabolism of the chicken.

As it is for mammalian species, growth hormone (GH) is indispensable for normal growth and development of avian species. In contrast to mammals, exogenous GH administration has little, if any, potential for improving the growth rate and feed efficiency of rapidly growing broilers; it is more likely to do so in older birds. This is at least partly because of age-related changes in tissue GH-binding activity and GH-receptor mRNA expression. The effects of GH on lipid deposition depends on the age of the bird and pattern of GH administration. Pulsatile, but not continuous, GH administration to older broilers seems to reduce fat deposition. As in rats, the bioactivity of GH might also depend on the pulse-induced cyclicity in GH receptors and GH-binding proteins. In chickens, GH is also a very potent lipolytic hormone, but seems to have no diabetogenic effect, which is reported in mammalian species. Both insulin-like growth factors have apparently no growth-promoting effects in normal growing broilers, but seem to have opposite effects on fat deposition. In contrast to GH, both insulin-like growth factors have a marked hypoglycemic effect. Whether all these effects are direct effects, or are mediated by secondary mechanisms, awaits further investigations.     

Caesarian section and neonatal care in the aardvark (Orycteropus afer)

A 5-yr-old aardvark (Orycteropus afer) was presented with dystocia as a result of fetal oversize. A caesarian section was performed using the technique used in domestic dogs. Anesthesia was induced with medetomidine and ketamine and maintained with isoflurane. The neonate was initially unable to suckle because of swelling and paralysis of the face and tongue following the prolonged pressure of the dystocia. A Haberman feeder was used successfully from 5 days of age, and the calf suckled unassisted after 9 days, from which point it was parent-reared. Most captive aardvark calves have been hand-reared. Although all four of this female's calves have required some initial medical assistance, only the first was hand-reared. A management strategy of overnight separation of the calves and dam has allowed the neonates sufficient rest and reduced injury and has reduced the need for hand-rearing.     

Pre-pubertal measurements of the somatotrophic axis as predictors of milk production in Holstein-Friesian dairy cows

This study investigated possible relationships between measurements of the somatotrophic axis in pre-pubertal dairy calves and subsequent milk yields. Endogenous growth hormone (GH) release was measured through a fed and fasted period in fifty 6-month-old Holstein-Friesian heifers and they were then challenged with growth hormone-releasing factor (GRF) to assess their GH release pattern. Insulin-like growth factor-I (IGF-I), insulin and glucose concentrations were measured in relation to time of feeding. Cows were subsequently monitored through their first three lactations to record peak and 305-day milk yields. In the first lactation, milk energy output for the first 120 days of lactation was also calculated. The mean 305-day milk yield increased from 7417 +/- 191 kg in the first lactation (n=37) to 8749 +/- 252 kg in the third (n=25). There were no significant relationships between any measures of GH secretion and peak or 305-day yield in any lactation. A highly significant positive relationship was established between the GH peak measured 10 min post-GRF challenge and 120-day milk energy values in the first lactation. This relationship was, however, only present in the sub-population of 12 cows culled after one or two lactations and was absent in the 25 animals remaining for the third lactation. There were no significant relationships between pre-pubertal IGF-I and fed or fasted insulin or glucose concentrations and any subsequent measurement of yield. The usefulness of GH secretagogue challenges in calves as a predictive test for future milk production is thus limited but may have some bearing on nutrient partitioning and longevity.     

Regulation of the bacterial intestinal implantation in infant born by caesarean section.

Studies were undertaken to determine the regulation of the bacterial intestinal implantation in 19 newborns delivered by caesarean section. Correlation was made with the infant feeding mode. The effect of human milk seemed to be the result of B. bifidum proliferation, in contrast to artificial alimentation that seemed to favour C. perfringens implantation. The question was raised by us as to whether this opposition was only related to alimentation. In fact, B. bifidum itself also had an effect as demonstrated by the lower mean counts of C. perfringens in bottle-fed infants carrying the bifido-bacterial flora (P = 0.05). None of the other faecal bacteria investigated in this study led to the same decrease.     

Proportion of litters of purebred dogs born by caesarean section

Objectives : To describe the frequency of caesarean sections in a large sample of pedigree dogs in the UK. Methods : Data on the numbers of litters born in the previous 10 years were available from a cross-sectional study of dogs belonging to breed club members (2004 Kennel Club/BSAVA Scientific Committee Purebred Dog Health Survey). In this survey 151 breeds were represented with data for households that had reported on at least 10 litters (range 10–14,15): this represented 13,141 bitches which had whelped 22,005 litters. The frequency of caesarean sections was estimated as the percentage of litters that were reported to be born by caesarean section (caesarean rates) and are reported by breed. The dogs were categorised into brachycephalic, mesocephalic and dolicocephalic breeds. Results : The 10 breeds with the highest caesarean rates were the Boston terrier, bulldog, French bulldog, mastiff, Scottish terrier, miniature bull terrier, German wirehaired pointer, Clumber spaniel, Pekingese and Dandie Dinmont terrier. In the Boston terrier, bulldog and French bulldog, the rate was > 80%. Clinical Significance : These data provide evidence for the need to monitor caesarean rates in certain breeds of dog.     

Postnatal ossification centers of the atlas and axis in miniature schnauzers

Postnatal ossification of the atlas and axis was studied in Miniature Schnauzers by examining alizarin-stained bone clearings, cleaned dry bones, radiographs, histologic sections, and arterially perfused bone clearings. Sixty-two pups (1 day to 16 weeks old) and 4 adults were examined. In 1-day-old pups, the atlas consisted of 3 separate ossification centers: a left and right neural arch center and midventrally, the intercentrum 1, which formed the body of the atlas. The axis contained 4 separate ossification centers: a left and right neural arch center; centrum 2 in the main part of the axis body; and centrum 1, which formed the caudal part of the dens and the cranial part of the axis body. By 6 weeks of age, the epiphysis on the caudal end of the axis body had begun to ossify. At this time, the intercentrum 2, which developed as a cuboidal ossification center intercalated between centrum 1 and centrum 2 in the middle of the cranial half of the axis body, also began to ossify. The centrum of the proatlas, which formed the apex of the dens, was first seen ossified in a 9-week-old pup. These 10 ossification centers were seen as constant and separate elements. In all dogs, the dens developed from 2 separate ossification centers: the centrum of the proatlas formed the cranial one-quarter, and centrum 1 formed the caudal three-quarters. Dens dysplasia is unlikely to be a result of failure of development of one of the ossification centers for the dens.(ABSTRACT TRUNCATED AT 250 WORDS)     

Detection and genotyping of porcine circovirus in naturally infected pigs by oligo-microarray

A rapid and reliable method for the identification of porcine circovirus (PCV) genotypes based on oligonucleotide microarray hybridization has been developed. The genotype-specific oligonucleotides (22-30 mer) immobilized on the surface of glass slides were selected to bind to the multiple target sites within the replication gene that are conserved among individual PCV genotypes. Cy5-labeled DNA targets were amplified in a PCR with primers common to both genotypes. The identification of PCV genotype was based on hybridization with several individual genotype-specific oligonucleotides. This approach combines the high sensitivity of PCR with the selectivity of DNA-DNA hybridization. The utility and feasibility of oligonucleotide microarray hybridization was evaluated by testing standard and 87 clinical isolates. Analysis of the specimens showed that this microarray-based method is capable of unambiguous identification of both genotypes and fivefold more sensitive than gel electrophoresis. Our results indicated that the oligonucleotide array is useful for the identification and discrimination of PCV from clinical isolates and specimens in a clinical laboratory.     

猪圆环病毒检测与分型寡核苷酸芯片的建立及应用

本研究应用寡聚核苷酸基因杂交技术建立了一种快速可靠的检测猪圆环病毒(PCV)基因型的方法.在PCV保守序列复制酶基因内设计了2对特异性引物,在此物之间设计了2种基因型特异的核苷酸探针(22～30 mer).通过PCR扩增Cy5标记的DNA片段与固定在玻片表面的探针杂交进行PCV基因分型.该技术结合了PCR方法的高度敏感性和DNA-DNA杂交技术的选择特异性.利用该方法对58倒临床样品进行了检测鉴定.结果显示,该技术能准确鉴别PCV病毒基因型.且其灵敏度是凝胶电泳的5倍.试验结果表明寡核苷酸基因芯片技术可有效地应用于PCV临床诊断和分子流行病学调查.     

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.     

Studies on maternally derived antibodies to Aujeszky's disease virus in piglets born to naturally or experimentally infected sows

The concentration of maternally derived antibodies to Aujeszky's disease virus was compared in 10 litters born to infected sows. Four sows had been naturally infected and six were experimentally infected. Both IgG and IgM were present in piglet sera during the first days of life. IgM antibodies went rapidly to undetectable levels; IgG persisted much longer. The duration was dependent upon the original concentration. There was a clear relationship between the clinical disease experienced by the sow and the titre of antibodies in serum and colostrum; sows which had been naturally infected or experimentally infected with a highly virulent strain passed onto their litters a high amount of specific antibodies while sows which after experimental infection presented only mild clinical signs had very low titres of neutralizing antibodies and their litters were virtually devoid of specific antibodies at 3 weeks after birth. A return to detectable levels of IgM was noticed in some litters at around 9 weeks postcolostrum intake suggesting a development of a specific immune response.     

Effect of fenbendazole and pyrantel tartrate on the induction of protective immunity in pigs naturally or experimentally infected with Ascaris suum

An experiment was conducted with 96 weanling pigs (avg initial wt 18.5 kg) divided into six treatment with two replicates of eight pigs each. Pigs in Treatments 1, 2 and 3 were penned in outside pens with dirt lots that previously were contaminated with A. suum ova to induce a natural ascaris infection. Pigs in Treatments 4, 5 and 6 were penned in an open-front building with solid concrete floors and were experimentally infected with 2,000 embryonated A. suum. ova on d 1, 15 and 29 of the experiment. Pigs in Treatments 1 and 4 were medicated with fenbendazole (FBZ, 3 mg/[kg BW.d]) for three consecutive days during three consecutive time periods. Pigs in Treatments 2 and 5 were medicated with pyrantel tartrate (PT, 106 mg/kg feed) for 28 d. Pigs in Treatments 3 and 6 served as infected, unmedicated controls. All pigs were challenged with 100 A. suum eggs 7 d after termination of the final FBZ treatment. All pigs were killed 66 d after challenge and worms were recovered. Fenbendazole treatment resulted in greater (P less than .07) average daily gain than PT treatment in pigs penned outside. Among inside pigs, FBZ treatment resulted in better (P less than .02) feed utilization than in controls. The FBZ and PT treatments reduced (P less than .03) the total number of A. suum, the length and weight of female ascarids and the length of male ascarids compared with controls. A natural continual infection with A. suum was less effective than experimental infection in inducing protective immunity in pigs.     

Microbial diversity in the large intestine of pigs born and reared in different environments

Pigs born outdoors and reared on deep litter (straw) have been reported to experience less of a growth check after weaning and have a higher dressing percentage than counterparts born and reared under conventional (indoor) systems. The reason(s) for this difference is/are presently unknown, but differences in the gut environment might contribute to these observations. PCR-DGGE techniques were used in this study to examine microbial diversity and banding patterns in the large intestine of piglets that were reared under different rearing conditions. Six piglets per treatment were euthanised at weaning (21 days) and at 7 days and 21 days after weaning from two extreme treatments [indoor-born: conventionally-raised after weaning (‘Indoor’) or outdoor-born, deep-litter raised after weaning (‘Outdoor’)]. The Shannon diversity index was calculated, and multivariate analysis of banding patterns was performed. Indoor pigs had a more diverse bacterial population at weaning and 21 days after weaning than Outdoor pigs. However at the end of the first week after weaning, outdoor-born and deep-litter pigs had a more diverse microbiota. The Shannon diversity index continued to increase with time after weaning in Outdoor pigs, which did not occur in Indoor pigs. Multivariate analysis of banding patterns showed there was a trend (P = 0.109) for a difference in microbial structure depending on housing type. There was also a significant (P < 0.001) effect of sampling time after weaning and a significant interaction (P < 0.001) between housing and time after weaning.     

Postnatal changes in lymphocyte function of dairy calves

Lymphocyte blastogenic response, B-lymphocyte population and antibody-producing activity of lymphocytes were determined to evaluate the lymphocyte function in neonatal calves during the first 4 weeks of life. The mean percentage of B-lymphocytes ranged from 10.2 to 12.5% during the first 14 days of life and from 15.3 to 17.5% in calves from the day 21 to day 28 after birth. The absolute number of B-lymphocytes increased significantly (P less than 0.05) from 370/microliters at birth to 736/microliters on day 28 after birth. The mean stimulation index of blastogenic response, measured by fluorometric assay, ranged from 5.75 to 6.61 with Con A, from 5.29 to 5.98 with PHA and from 1.89 to 2.50 with PWM. The mean (+/- S.D.) number of plaque forming cells ranged from 22.0 (+/- 12.0) to 24.7 (+/- 9.2) in cultured lymphocytes from 5 calves at birth to 14 days after birth and their levels increased markedly from 137.8 (+/- 88.3) to 162.0 (+/- 57.8) in lymphocytes from 20 days to 28 days after birth. The present study showed that antibody-producing activity of lymphocytes is lower in calves within 3 weeks after birth compared to that of calves 3 weeks after birth, indicating that neonatal calf lymphocytes have a low antibody-producing activity at least up to 1 month after birth.     

Effect of enrofloxacin in the carrier stage of Haemophilus parasuis in naturally colonized pigs

The purpose of this study was to determine the effect of enrofloxacin in the carrier stage of Haemophilus parasuis in naturally colonized weaned pigs. Twenty-three pigs colonized by H. parasuis received either 7.5 mg/kg body weight (BW) of enrofloxacin or a saline solution intramuscularly at weaning. Nasal and tonsillar swab samples were collected daily throughout the study and at necropsy and tested by quantitative polymerase chain reaction (qPCR). The H. parasuis isolates obtained from samples collected at necropsy were subjected to genotyping by enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) and a multiplex PCR for the detection of the virulence-associated trimeric autotransporter (vtaA) genes. Haemophilus parasuis was detected in the nasal cavity and tonsils of pigs in the control group throughout the study. Antibiotic-treated pigs tested negative for H. parasuis at 1 d post-treatment and the proportion of nasal samples that tested positive was higher for control pigs than for treated pigs at 1, 2, 3, 4, 5, 6, and 7 d post-treatment and at 2, 4, and 5 d post-treatment for tonsil samples (P < 0.003). Genotyping by ERIC-PCR demonstrated that pigs were colonized with a common H. parasuis strain at the end of the study. Isolates were negative for the vtaA gene, which indicates the absence of vtaA virulence factor. In conclusion, enrofloxacin significantly reduced the H. parasuis load in naturally colonized pigs, but was unable to completely eliminate the organism.