Concentrations of selected immunological parameters in the serum and processing fluid of suckling piglets and the serum and colostrum of their mothers

BACKGROUND

Blood sampling from neonatal piglets is related to multiple disadvantages. Therefore, a new, alternative matrix is required to assess piglets' early immune status efficiently. The present study aimed to assess the usefulness of processing fluid for determining selected piglets' immune parameters. 264 pigs - 31 sows, 146 male piglets, and 87 female piglets from commercial indoor farrow-to-finish pig herd were included in this study. 264 serum, 31 colostrum, and 146 processing fluid samples were collected. Serum was collected from all animals, colostrum was collected from sows, and processing fluid was collected from male piglets only. Using commercial ELISA tests, the concentration of various immunoglobulins, cytokines, and acute phase proteins was assessed in each matrix. Statistical analyses were employed to determine differences in the concentration of measured indices between piglets' serum and processing fluid and correlations in the concentration of tested indices between particular sets of matrices.

RESULTS

Statistical analyses did not reveal significant differences in the IgG, IgA, IL-1β, IL-4, IL-6, and IFN-γ concentration between piglets' serum and processing fluid (p > 0.05). A positive correlation (p < 0.05) regarding the concentration of some indices between processing fluid and samples collected from sows was also observed.

CONCLUSIONS

Processing fluid can be considered a promising alternative to blood for assessing some immunological indices in piglets, such as IgG, IgA, IL-1β, IL-4, IL-6, and IFN-γ, and, possibly, in the indirect assessment of some indices in lactating sows, including IgA, IL-1β, IL-4, IL-6, IL-8, IFN-γ, or Pig-MAP.

Pre-conception maternal helminth infection transfers via nursing long-lasting cellular immunity against helminths to offspring

Maternal immune transfer is the most significant source of protection from early-life infection, but whether maternal transfer of immunity by nursing permanently alters offspring immunity is poorly understood. Here, we identify maternal immune imprinting of offspring nursed by mothers who had a pre-conception helminth infection. Nursing of pups by helminth-exposed mothers transferred protective cellular immunity to these offspring against helminth infection. Enhanced control of infection was not dependent on maternal antibody. Protection associated with systemic development of protective type 2 immunity in T helper 2 (T_H2) impaired IL-4Rα^-/- offspring. This maternally acquired immunity was maintained into maturity and required transfer (via nursing) to the offspring of maternally derived T_H2-competent CD4 T cells. Our data therefore reveal that maternal exposure to a globally prevalent source of infection before pregnancy provides long-term nursing-acquired immune benefits to offspring mediated by maternally derived pathogen-experienced lymphocytes.

Supplementing dams with both arachidonic and docosahexaenoic acid has beneficial effects on growth and immune development

Omega-3 long-chain polyunsaturated fatty acids (LCPUFAS) modulate immune cells in vitro and in vivo. This study investigated the effects of enriching the maternal diet with the n-6 and n-3 LCPUFAs, arachidonic (20:4n-6, 0.6%wt ARA) and docosahexaenoic acid (22:6n-3, 0.32%wt DHA), or 1:1 and 2:1 ratios (ARA: DHA) on total lipids in milk, total lipids, and immunophenotypes in plasma, lymph nodes, and spleen from isolated immune cells from 28d old pups. From day 15 of gestation to day 3 pp, Sprague-Dawley dams were fed a commercial chow. On day 3 pp litters were culled and pups (4 males and 2 females) randomly cross-fostered to dams who were randomized to one of the 5 experimental diets resulting in 20 male and 10 female pups/diet group. Dams fed ARA or ARA: DHA had 28-36% more 20:4n-6 in milk and feeding DHA or ARA: DHA doubled 22:6n-3 in milk lipids (P<0.05). Feeding 1:1 or 2:1 ARA: DHA resulted in greater pup weight at weaning (P<0.05). Compared to the control pups, ARA + DHA fed pups had a lower proportion of splenic CD45RA+ lymphocytes. In summary, postpartum supplementation with a combination of ARA + DHA, compared to ARA or DHA alone, resulted in a higher content of ARA and DHA in dam's milk and tissues and had positive effects on growth, accompanied by evidence of progression toward a mature immune phenotype, and suggests a need for ARA when DHA is supplemented in the early diet. Additional investigations are needed of ARA immunomodulation to better understand and estimate nutritional requirements for LCPUFAs during early development.

Effects of octreotide on jejunal hypersensitivity triggered by Cryptosporidium parvum intestinal infection in an immunocompetent suckling rat model

BACKGROUND

Similar to other bacterial or protozoan infections, human cryptosporidiosis may trigger postinfectious irritable bowel syndrome (IBS)-like symptoms, a condition in which enhanced visceral perception of pain during intestinal distension plays a pivotal role. In an immunocompetent suckling rat model which mimicks features of postinfectious IBS, Cryptosporidium parvum infection induces long-lasting jejunal hypersensitivity to distension in association with intestinal activated mast cell accumulation. The aim of the present study was to explore in this model whether octreotide, a somatostatin agonist analog, could prevent the development of jejunal hypersensitivity and intestinal mast cell/nerve fiber accumulation.

METHODS

Five-day-old Sprague-Dawley rats were infected with C. parvum and treated 10 days later with octreotide (50 g kg(-1) day(-1), i.p.) for 7 days.

KEY RESULTS

Compared with untreated infected rats, octreotide treatment of infected rats resulted in increased weight gain [day 23 postinfection (PI)], decreased food intake (day 16 PI), and a reduction in jejunal villus alterations (day 14 PI), CD3(+) IEL (day 37 PI) and mast cell (days 37 and 50 PI) accumulations, nerve fiber densities (day 50 PI), and hypersensitivity to distension (day 120 PI). In uninfected rats, the effects of octreotide treatment were limited to higher weight gain (days 16 and 23 PI) and decreased food intake (day 23 PI) compared with uninfected-untreated rats.

CONCLUSIONS & INFERENCES

Data confirms the relevance of the present rat model to postinfectious IBS studies and prompt further investigation of somatostatin-dependent regulatory interactions in cryptosporidiosis.

Transfer of maternal haptoglobin to suckling piglets

The acute phase protein haptoglobin (Hp) exerts immune modulating functions in the innate and adaptive immune system. In pigs, serum Hp concentrations are linked to impaired growth performance. There is little information on Hp in newborn piglets and the onset of endogenous Hp synthesis. In the first experiment we analyzed Hp concentrations in colostrum from sows (n=5) and serum from their off-spring (n=43) during the first 12h of life. The piglets were divided in a colostrum group which was allowed to suckle and a colostrum-deprived group which received a Hp-free milk replacer. We were able to show that serum Hp in newborn piglets increased 3h after colostrum intake whereas serum Hp remained low in colostrum-deprived littermates. The absorption of colostral Hp in the jejunum could be shown via immunohistochemistry. In colostrum suckled piglets, endogenous Hp synthesis in the liver increased 9h after birth, no increase in Hp mRNA was observable during the first 12h of life in colostrum-deprived piglets. From our results we concluded that maternal Hp is transferred to newborn pigs via colostrum and the stimulus for the increase in Hp synthesis is mediated by colostrum. In a second experiment we analyzed Hp in colostrum, milk and serum from sows (n=43) and their off-spring (n=442) from birth until weaning. Haptoglobin was high in colostrum (1.11 ± 0.10mg/ml) and declined to lower but stable milk levels (0.36 ± 0.08 mg/ml) until weaning. Colostral Hp and daily litter weight gain were negatively correlated (r=-0.5, p<0.01) whereas the relationship between piglets serum Hp and daily weight gain was weaker (r=-0.22, p<0.05). We therefore speculate that maternal Hp exerts systemic actions in piglets.

Clinical outcome of calves with failure of passive transfer as diagnosed by a commercially available IgG quick test kit

The efficacy of an IgG quick test in detecting calves with failure of passive transfer was assessed. The test was carried out on 97 male calves, 38% of which were negative (IgG < 10 mg/mL). Morbidity and mortality due to infectious diseases were significantly higher in the negative group showing that the quick test is useful in identifying calves more susceptible to infectious disease.

Prolonged exclusive breastfeeding reduces autoimmune diabetes incidence and increases regulatory T-cell frequency in bio-breeding diabetes-prone rats

BACKGROUND

Previously, we reported that exclusive breastfeeding delayed and partially protected bio-breeding diabetes-prone (BBDP) rats from spontaneous autoimmune diabetes development. To investigate whether this protection results from modulation of the (mucosal) immune system, the present study was designed to analyse the effect of nutrition early in life on the immune status of BBDP rats.

METHODS

The breastfeeding period of BBDP pups was extended or not, while allowing half of the pups to eat during that period whereas the other half received only breast milk. Cytokine profiles as well as naturally occurring regulatory T-cell frequencies were measured over time in the mesenteric lymph nodes (MLNs) and spleen.

RESULTS

Prolonged exclusive breastfeeding partially protects against autoimmune diabetes development and resulted in elevated levels of natural regulatory T cells (CD4(+) CD25(+) FoxP3(+)) in MLNs and spleen directly after weaning and throughout life. Stimulation of MLN cells from rats that ingested solid food during the nursing period showed massive secretion of interferon gamma (IFN-gamma), interleukin (IL)-4 and IL-10, whereas MLN cells from exclusive breastfed rats did not. In contrast, transforming growth factor beta (TGF-ss) was secreted equally by all groups.

CONCLUSIONS

Prolonged exclusive breastfeeding partially protects BBDP rats from autoimmune diabetes development. Interestingly, ingestion of solid food during the weaning period completely abolishes this protective effect. The protective effect of exclusive breastfeeding correlates with higher levels of naturally occurring regulatory T cells throughout life and low cytokine secretion at weaning.

The development of microflora and production of short-chain fatty acids in the digestive tract of suckled piglets and replacer-fed piglets

The objective of this study was to obtain knowledge about the postnatal development of microflora and the production of short-chain fatty acids in 24 piglets suckled by sows and 26 piglets fed on milk replacement. On day 14 piglets which had received no colostrum had higher counts of Enterobacteriaceae (p < 0.001) and coliform bacteria (p <0.001) in the jejunum contents than piglets suckled by their mother sow. Depending on age, concentrations of both lactic and acetic acid were higher in the contents of the small intestine of piglets suckled by sows compared to milk replacer-fed piglets. Replacement of maternal milk by artificial feeding adversely affected the postnatal development of the piglets. This resulted in higher morbidity and mortality in those piglets.

A proteomic approach to analysis of antimicrobial activity in marsupial pouch secretions

We have documented the antimicrobial activity of pouch secretions of the tammar wallaby, Macropus eugenii, over the period leading up to birth and after birth of the young animal. This activity was greatest against the Gram-negative Escherichia coli and highest at the time of birth. Fractionation of the pouch secretions showed that activity at different times over the reproductive periods was associated with different molecular-weight (MW) components, with compounds in the range up to 50 kDa active immediately prior to and at the time of birth. Proteomic analysis using 1 and 2DE PAGE and LC-MS/MS identified the major components of the pouch secretions at these times, at a range of pI's and MWs. The majority of high-confidence identifications, at a wide range of pI's and MW, were beta-lactoglobulin, a known component of marsupial milk. We subsequently conducted a proteomic analysis of mammary gland secretions and digest products from the gut of the young animal, using 2DE PAGE and MALDI MS/MS, to confirm its source and compare it with the observed MW and pI's of beta-lactoglobulin. Although we did not directly identify an effector molecule responsible for antimicrobial activity, these results lead us to propose that beta-lactoglobulin plays a role in the protection of the young marsupial, a role previously thought to be primarily due to specific secretions from the epithelial surface of the pouch.

Long-term effect of early protein malnutrition on growth curve, hematological parameters and macrophage function of rats

To evaluate the long-term effect of mild-early maternal protein malnutrition on weight gain, hematological parameters and macrophage function in rats at adult age, we compared rats whose dams were fed diets containing either 9.5% (low protein-LPD) or 23% protein (normal-NPD) for the first 12 d of lactation. At 80 d of age, the functions of spreading, phagocytosis and killing Candida albicans were determined in resident peritoneal macrophages, whereas leukocytes and red blood cells were counted in peripheral blood. The number of resident peritoneal macrophages from LPD was the same as from NPD, but the ability of spreading and phagocytosing opsonised yeast was impaired. Besides, they were not able to block the germ tube formation or kill C. albicans to the same extent as in the control group. The low protein diet produced a significant reduction in the pups' growth and in hematological parameters although no difference was found in leukocyte counts. Taken together the data suggest that protein malnutrition during early lactation induces permanent alterations in macrophage function, body composition and hematological status, which are not restored completely even after a normal protein diet is supplied.

Maternal milk contains antimicrobial factors that protect young rabbits from enteropathogenic Escherichia coli infection

Enteropathogenic Escherichia coli (EPEC) colibacillosis represents a major cause of lethal diarrhea in young children in developing countries. EPEC strains also infect numerous mammal species and represent a major economical problem in rabbit industry. Protection against this pathogen is a challenging goal both in humans and in other mammal species. Despite a good knowledge of the pathogenicity mechanisms of EPEC, the intrinsic and environmental factors that control the expression of EPEC virulence in mammals remain unknown. For instance, the exacerbated sensitivity of young mammals to EPEC infection is still unexplained. Our goal was to investigate if age or other factors, like milk consumption, could be determinants that trigger the disease. We used rabbits as an animal model to study the role of milk in the sensitivity to an EPEC infection. Weaned and suckling rabbits were orally inoculated with EPEC strain E22 (O103:H2:K-) at 28 days of age, and the evolution of the disease was investigated in the two groups. In addition, in order to better characterize the interactions between milk and EPEC, we determined in vitro bacterial growth and the abilities of EPEC cells to adhere to epithelial cells in the presence of milk. Our results demonstrate a protective role of milk in vivo in association with in vitro antibacterial activity. These effects are independent of the presence of specific anti-EPEC antibodies.

Transfer of maternal cytokines to suckling piglets: in vivo and in vitro models with implications for immunomodulation of neonatal immunity

Maternal cytokines may play instructive roles in development of the neonatal immune system. However, cytokines in colostrum and milk and their transfer from mothers to neonates have not been well documented, except for TGF-beta. Swine provide a unique model to study lactogenic cytokines because the sow's impermeable placenta prohibits transplacental passage. We investigated IL-6 and TNF-alpha (pro-inflammatory), IFN-gamma and IL-12 (Th1), IL-10 and IL-4 (Th2) and TGF-beta1 (Th3) concentrations in sow serum and colostrum/milk and serum of their suckling and weaned piglets and in age-matched colostrum-deprived gnotobiotic piglets. All cytokines were detected in colostrum/milk and correlated with concentrations in sow serum except for mammary-derived TNF-alpha and TGF-beta1. Detection of IL-12 and TGF-beta1 in pre-suckling and colostrum-deprived gnotobiotic piglet serum suggests constitutive production: other cytokines were undetectable confirming absence of transplacental transfer. Peak median cytokine concentrations in suckling piglet serum occurred at post-partum days 1-2 (IL-4>IL-6>IFN-gamma>IL-10). The effects in vitro of physiologically relevant concentrations of the two predominant lactogenic cytokines (TGF-beta1 and IL-4) on porcine naive B cell responses to lipopolysaccharide (LPS) and rotavirus (RV) were investigated. High (10 ng/ml) TGF-beta1 suppressed immunoglobulin secreting cell responses to LPS and rotavirus; low concentrations (0.1 ng/ml) promoted isotype switching to IgA antibody. Interleukin-4 induced inverse dose-dependent (0.1 ng>10 ng/ml) isotype switching to IgA and enhanced IgM secreting cell responses to LPS and rotavirus. In summary, we documented the transfer and persistence of maternal cytokines from colostrum/milk to neonates and their potential role in Th-2 biased IgA responses and reduced immunologic responsiveness of neonates.

Identification of lipopolysaccharide-binding proteins in porcine milk

Septicemia and endotoxemia initiated by bacterial lipopolysaccharide (LPS) are relatively common in suckling and weaned piglets. Maternal milk is a source of both nutrition and immune protection for piglets. Passive transfer of colostral antibodies is necessary for protection of neonatal piglets against diseases, but the concentration of immunoglobulins in milk rapidly declines during the 1st wk of lactation in all mammals. We hypothesized, therefore, that nonimmunoglobulin substances in milk contribute to the innate protection of neonates against septicemia during the suckling period. Using LPS-affinity chromatography for isolation of LPS-binding proteins and liquid chromatography-mass spectrometry for their identification, we identified in porcine milk the following proteins with LPS-binding capacity: lactoferrin, soluble CD14, serum amyloid A, alpha-S1 casein, beta-casein, and kappa-casein. For lactoferrin, alpha-S1 casein, and kappa-casein, in vitro pepsin digestion did not inhibit LPS-binding activity, whereas combined digestion with pepsin and pancreatin abolished it. The biologic functions of these LPS-binding proteins and peptides were not determined.

Immunization of sows in an integrated pig-breeding herd using a homologous inactivated Salmonella vaccine decreases the prevalence of Salmonella typhimurium infection in the offspring

The efficacy of a homologous vaccination in preventing infection of suckling piglets with Salmonella (S.) Typhimurium was evaluated after an immunization of pregnant sows using an inactivated herd-specific S. Typhimurium vaccine. Twenty-five pregnant sows were vaccinated three times antepartum. The efficiency of this vaccine regime was assessed by comparison with a control group of 37 sows and their suckling piglets, which were daily treated with enrofloxacin from day 14 antepartum until the day of weaning. From the first day of life until day 142 post-partum, faecal samples of the piglets were collected and analysed for Salmonella shedding. In parallel, systemic antibody responses were monitored using a whole cell-based isotype-specific enzyme-linked immunosorbent assay (ELISA). The bacteriological investigation showed marked effects of vaccination. Salmonella Typhimurium could not be detected in any of the faecal samples of the piglets from the vaccinated sows. In contrast, the piglets of the group with long-time antibiotic treatment shed salmonellae rating to 47.4% of the animals. Furthermore, the offspring from vaccinated sows showed significantly decreased antibody activities of immunoglobulin (Ig)A and IgG. These bacteriological and serological results indicate a significantly lower Salmonella prevalence in piglets of the vaccinated group. As this study shows, the presented strategy of vaccination of pregnant sows with an inactivated Salmonella vaccine seems to be a suitable measure in decreasing Salmonella prevalence in offspring of infected sows.

Antibody response to Mycoplasma hyopneumoniae infection in vaccinated pigs with or without maternal antibodies induced by sow vaccination

Vaccination with bacterins is an important tool for the control of Mycoplasma hyopneumoniae infection of pigs. Because such vaccination often involves piglets that have suckled M. hyopneumoniae antibody-positive dams it is important to understand the effect of pre-existing (passively acquired) antibody on vaccine-induced immunity. To investigate this issue experimentally, 20 sows that were seronegative for M. hyopneumoniae were selected from a M. hyopneumoniae-infected herd and then randomly allocated to one of four treatment groups (five sows/group): Group A, vaccinated sows/vaccinated piglets; Group B, vaccinated sows/non-vaccinated piglets; Group C, non-vaccinated sows/vaccinated piglets; Group D, non-vaccinated sows/non-vaccinated piglets. Sows (Groups A and B) were vaccinated 14 days before farrowing and seroconverted within the next 14 days. Conversely, none of the non-vaccinated sows was seropositive at farrowing. Piglets (Groups A and C) were vaccinated when they were 7 days of age. Regardless of treatments none of the piglets had any evidence of an active immune response until many of those of Groups A and C and a few of those of Groups B and D seroconverted after it had been shown that at least some pigs of all groups had been naturally infected with a field strain of M. hyopneumoniae. This pattern of immune responsiveness (i.e. the collective results of Groups A, B, C and D) suggested that vaccination of pigs had primed their immune system for subsequent exposure to M. hyopneumoniae, and that passively acquired antibody had little or no effect on either a vaccine-induced priming or a subsequent anamnestic response. According to the statistical analysis sow serological status did not interfere with the antibody response in early vaccinated piglets. In conclusion, the results pointed out that early vaccination of piglets may assist M. hyopneumoniae control independently from the serological status of sows.

Immunoglobulin concentrations in feline colostrum and milk, and the requirement of colostrum for passive transfer of immunity to neonatal kittens

The purpose of this study was to clarify whether cats have a colostral and milk phase of lactation differentiated by concentrations of immunoglobulins, and whether colostrum ingestion by newborn kittens is essential for optimal transfer of passive immunity. Milk from specific pathogen-free queens was analyzed for IgG and IgA concentrations from parturition through 6 weeks of lactation. Serum IgG and IgA concentrations from birth through 8 weeks of age were determined for colostrum-fed kittens, colostrum-deprived kittens that were fed a milk replacer, and colostrum-deprived kittens that were fostered onto queens in the milk phase of lactation. The total IgG and IgA concentrations in milk were significantly higher on the day of parturition than on day 7 of lactation, indicating cats do have a colostral phase of lactation. The predominant immunoglobulin in both colostrum and milk was IgG. The serum IgG concentrations in colostrum-deprived kittens fostered on queens in the milk phase of lactation were similar to colostrum-deprived kittens fed a milk replacer, and the concentrations were significantly lower than in colostrum-fed kittens for the first 4 weeks of life. The serum IgA concentrations in both colostrum-deprived groups were significantly lower than colostrum-fed kittens on day 2 after parturition, but were similar thereafter. Colostrum-deprived kittens fostered onto queens in the milk phase of lactation had failure of passive transfer of maternal antibodies. Protective concentrations of immunoglobulins can be restored in kittens with failure of passive transfer of immunity by parenteral administration of adult cat serum, but not by fostering on queens in mid-lactation.

Effect of passive transfer status on preweaning growth performance in dairy lambs

OBJECTIVE

To evaluate the effect of passive transfer status, determined by measuring serum IgG concentration 24 hours after parturition, on preweaning growth performance in dairy lambs.

DESIGN

Prospective observational study.

ANIMALS

20 healthy Sardinian dairy lambs.

PROCEDURES

Serum IgG concentration was measured 24 hours after birth. Body weight was measured at birth and at the time of weaning 28 days (ie, 27 to 29 days) after birth. Mean daily gain from birth to day 28 and day 28 weight were used as measures of preweaning growth performance. Regression analysis was used to evaluate associations between serum IgG concentration 24 hours after birth and measures of preweaning growth performance.

RESULTS

Mean +/- SD serum IgG concentration 24 hours after birth was 24.6 +/- 17.5 mg/mL. Mean body weights at birth and weaning were 2,696 +/- 937 g and 9,253 +/- 2,116 g, respectively, and mean daily gain was 234 +/- 63 g/d. No significant association was detected between serum IgG concentration 24 hours after birth and birth weight. However, serum IgG concentration 24 hours after birth was significantly associated with mean daily gain (R(2) = 0.25). Each 1 mg/mL increase in serum IgG concentration 24 hours after birth was associated with a 1.8 g/d increase in mean daily gain and a 60.8-g increase in day 28 weight.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that passive transfer status, determined as serum IgG concentration 24 hours after birth, was a significant source of variation in preweaning growth performance in dairy lambs.

Evaluation of surrogate markers for passive transfer of immunity in kittens

OBJECTIVE

To identify surrogate markers of passive transfer of immunity in kittens.

DESIGN

Prospective clinical trial.

ANIMALS

55 kittens from 12 specific-pathogen-free queens.

PROCEDURE

Kittens were allocated at birth into colostrum-fed (n = 27) and colostrum-deprived (28) groups. Blood was collected at birth and on days 1, 2, 4, 7, 14, 28, and 56. Serum samples were analyzed for activities of alkaline phosphatase (ALP), alanine aminotransferase, aspartate aminotransferase, creatine kinase, lactate dehydrogenase, gamma-glutamyltransferase, amylase, and lipase and for concentrations of albumin, total protein, bilirubin, urea nitrogen, creatinine, cholesterol, glucose, calcium, phosphorus, and triglycerides by use of an automated analyzer. Total serum solids concentrations were estimated by use of refractometry. Serum IgG concentrations were quantified by use of radial immunodiffusion.

RESULTS

All kittens were agammaglobulinemic at birth. Colostrum-fed kittens had significantly higher IgG concentrations than did colostrum-deprived kittens from 1 though 28 days of age. Transient significant differences in serum biochemical variables between the colostrum-deprived and colostrum-fed groups were substantially resolved by day 4. Passive transfer of immunity could be reliably determined at 1 day of age and to a lesser extent at 2 days of age only by measurement of serum activity of ALP.

CONCLUSIONS AND CLINICAL RELEVANCE

Adequacy of passive transfer in kittens initially correlated with serum activity of ALP, but quantification of serum IgG concentration was necessary after 2 days of age.

Effects of feeding antibiotic-free creep feed supplemented with oligofructose, probiotics or synbiotics to suckling piglets increases the preweaning weight gain and composition of intestinal microbiota

The objective of this study was to determine whether feeding an antibiotic-free creep feed supplemented with either oligofructose, probiotics or synbiotics to suckling piglets influences growth performance, the gut microflora, gut morphology and hematological traits at weaning. Twenty sows with 10 piglets each were randomly assigned to one of four treatments. The treatments consisted of a control (antibiotic-free) diet, 0.2% oligofructose (OF), 0.3% probiotics or 0.5% synbiotics (mixture of 0.2% OF+0.3% probiotics). Piglets were offered the diet ad libitum from 7 d after birth until one day after weaning (21 d of age). At the day after weaning, blood samples were collected from the jugular vein to determine the immune response. Digesta samples of the ileum and colon were collected to determine the microbial composition. Tissue segments from the duodenum and ileum were collected for morphometric measurements of the small intestine. The average daily weight gain was significantly higher for piglets fed the OF or synbiotics diet compared with the pigs fed the control diet. The hematological traits (the concentration of lymphocytes and neutrophils in whole blood) were not affected by the diet. Piglets fed the OF, probiotics or synbiotics diet had a significantly decreased number of total coliform bacteria in the colon. Feeding OF, probiotics or synbiotics significantly increased the population of bifidobacteria in the ileum compared to the control. In the colon, the probiotics and synbiotics diet significantly increased the number of bifidobacteria compared with the control diet. The results of this experiment showed that supplementation of oligofructose or synbiotics to an antibiotic-free creep feed during the preweaning period affected gut microbial population and performance of piglets.

Influence of supplementation of all-rac-α-tocopheryl acetate preweaning and vitamin C postweaning on α-tocopherol and immune responses of piglets1

This study was designed to test whether dietary maternal supplementation of all-rac-alpha-tocopheryl acetate during lactation and dietary vitamin C supplementation after weaning could increase the alpha-tocopherol status pre- and postweaning and the immune responses of piglets postweaning. The experiment involved 12 crossbred sows that were fed increasing levels of all-rac-alpha-tocopheryl (70, 150, and 250 IU/kg, as-fed basis) during lactation. After weaning (d 28 of age), litters were divided into two groups that were supplemented with or without vitamin C (500 mg/kg of feed, as-fed basis). Milk and blood samples were obtained from the sows during lactation. Pigs were bled at 4, 16, 28, 35, 42, and 49 d of age. Liver, heart, muscle, and s.c. adipose tissues were collected (on 28, 35, 42, and 49 d of age) and analyzed for alpha-tocopherol. On the same days, alveolar macrophages of the lungs were collected, and analyzed for the concentration of alpha-tocopherol and its stereoisomer composition, fatty acid composition, and release of prostaglandin E2, leukotriene B4, and thromboxane B2. Increasing dietary all-rac-alpha-tocopheryl acetate concentration increased the concentration of alpha-tocopherol in plasma (P = 0.02) and milk (P = 0.007) of sows, and the sow milk concentrations of alpha-tocopherol and vitamin A were greater on d 2 of lactation than later on during lactation. The plasma concentration of alpha-tocopherol in piglets decreased from d 4 to later on during suckling (P < 0.001) and again as the postweaning period progressed (P < 0.001). When lipid-standardized, plasma alpha-tocopherol was increased in piglets of sows fed 250 IU of all-rac-alpha-tocopheryl acetate compared with other sow-groups (P = 0.005). At 28 d of age, alpha-tocopherol concentrations in tissues were increased with supplementation of the high dietary all-rac-alpha-tocopheryl acetate levels to the sows; however, after weaning, a decrease in alpha-tocopherol concentration in most tissues (except liver) was observed, but the decrease tended to be less in the muscle (P = 0.099) and adipose tissue (P = 0.11) of piglets suckling sows fed 150 and 250 IU of all-rac-alpha-tocopheryl acetate. Vitamin C supplementation after weaning increased liver alpha-tocopherol (P = 0.01) and serum immunoglobulin M concentration (P = 0.04), and vitamin C supplementation increased the proportion of the RRR-alpha-tocopherol (P = 0.03) at the expense of the RRS-stereoisomer form (P = 0.05) of alpha-tocopherol in alveolar macrophages of the piglets. In conclusion, this study on maternal all-rac-alpha-tocopheryl acetate and postweaning vitamin C supplementation suggests a nutritional strategy for increasing alpha-tocopherol status and immune responses of weaned piglets.

Immunization protocols against Cryptosporidium parvum in ovines: protection in suckling lambs

Ovine colostrum and milk from immunized ewes were tested for their ability to prevent cryptosporidiosis in the lambs experimentally infected with 10(6) oocysts of Cryptosporidium parvum at 36-48 h of age (day 0 post-infection). All lambs became infected and developed clinical cryptosporidiosis. However, lambs fed by immunized dams have shown shedding involved, significantly, fewer oocysts and lasted for a shorter period than in control lambs. In addition, diarrhoea was less severe. The best results emerged in lambs of ewes immunized by intramuscular injection of an emulsion of 2 ml of Freund's complete adjuvant and 2 ml of C. parvum antigen in sterile phosphate buffered saline solution, administrated four weeks before parturition, together with an intramammary infusion of 25 microg of antigen in 2 ml of sterile PBS emulsified in 2 ml of Freund's incomplete adjuvant, which showed the highest anti-C. parvum titres in lacteal secretions. In their case, the onset of output of oocysts was delayed by two days, the patent period was shortened by three days, their diarrhoea continued for only three days, and the quantity of oocysts shed decreased by 77%. The outcome was that at the end of the study they had a live weight gain of 2 kg more than the lambs in the control group. These results indicate that lactogenic immunoprophylaxis should help mitigate the financial losses caused by cryptosporidiosis in small ruminants, as well as reducing the risk of infection of humans through the decreased contamination of the environment with oocysts.

Evaluation of serum enzyme activities as predictors of passive transfer status in lambs

OBJECTIVE

To determine the associations between serum IgG concentration and serum activities of gamma-glutamyltransferase (GGT), alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and pseudocholinesterase for the potential use of these serum enzymes as predictors of passive transfer status in neonatal lambs.

DESIGN

Prospective observational study.

ANIMALS

47 Sardinian lambs from birth to 2 days old.

PROCEDURE

Serum enzyme activities were measured by use of commercially available kits and a clinical biochemical analyzer. Serum IgG concentration was determined by single radial immunodiffusion. Associations between serum IgG concentration and the activity of each serum enzyme were established by use of regression analysis.

RESULTS

A significant correlation was detected between serum IgG concentration and serum GGT activity in 1- and 2-day-old lambs. Minimal correlations were detected between serum IgG concentration and serum alkaline phosphatase activity in 1-day-old lambs and serum pseudocholinesterase activity in 1- and 2-day-old lambs. No significant associations were detected between serum IgG concentration and serum activities of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase. A multiple linear regression model was accurate for the estimation of the natural logarithm of serum IgG concentration as a function of the natural logarithm of serum GGT activity and of the age of lambs at the time of sampling (adjusted R2 = 0.89). This model was then used to calculate the serum GGT activity equivalent to various serum IgG concentrations for 1- and 2-day-old lambs.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that passive transfer status in neonatal lambs can be successfully predicted by measurement of serum GGT activity but not by measurement of the other enzymes tested.

Resistance of Santa Inês and Ile de France suckling lambs to gastrointestinal nematode infections

A trial was carried out to determine the resistance to natural infection by gastrointestinal nematodes in 12 Santa Inês and nine Ile de France lambs before weaning. Faecal samples were obtained for faecal nematode egg counts (FEC). Blood samples were collected to determine packed cell volume (PCV), total plasma protein levels and peripheral eosinophil counts. Most Ile de France lambs (77.8%) were treated with an anthelmintic at 43 days of age, while 50% off Santa Inês lambs were treated at weaning, 57 days of age. The mean PCV values were normal in Santa Inês lambs, while in Ile de France lambs showed lower values reaching 22.3% at 43 days of age. The lowest mean plasma protein values were observed in Ile de France lambs (4.13 g/dl) at 43 days of age and in Santa Inês lambs (5.0 g/dl) at 57 days of age. Before weaning, Santa Inês lambs were susceptible to natural infections by gastrointestinal nematodes but with a greater capacity to stand the adverse effects of parasitism compared to Ile de France lambs.

Passive protection to bovine rotavirus (BRV) infection induced by a BRV VP8* produced in plants using a TMV-based vector

We have previously reported on the use of a tobacco mosaic virus (TMV) vector TMV-30B to express foreign viral antigens for use as experimental immunogens. Here we describe the development of an improved TMV-30B vector that adds a sequence of 7 histidine residues to the C-terminus of recombinant proteins expressed in the vector. We used this TMV-30B-HISc vector to express the VP8* fragment of the VP4 protein from bovine rotavirus (BRV) strain C-486 in plants. Recombinant VP8* protein was purified from N. benthamiana leaves at 7 days post-inoculation by immobilized metal affinity chromatography. The plant-produced VP8* was initially detected using anti-His tag mAb and its antigenic nature was confirmed using both monoclonal and polyclonal specific antisera directed against BRV. Adult female mice, inoculated by the intraperinoteal route with an immunogen containing 4 microg of recombinant VP8*, developed a specific and sustained response to the native VP8* from the homologous BRV. Eighty five percent of suckling mice from immunized dams that were challenged with the homologous virus at the fifth day of age were protected from virus as compared to 35% of the pups from mothers immunized with a control protein. These results demonstrate that the plant-produced VP8* was able to induce passive protection in the new born through the immunization of dams. This suggests that the technology presented here provides a simple method for using plants as an inexpensive alternative source for production of recombinant anti-rotavirus antigens.

Binding of a monoclonal antibody positively correlates with bioactivity of the F4 fimbrial adhesin FaeG associated with post-weaning diarrhoea in piglets

Piglets are susceptible to F4 (K88)+ enterotoxigenic Escherichia coli (ETEC)-induced neonatal and post-weaning diarrhoea. The F4 fimbriae are composed of some minor subunits and the major subunit FaeG that also constitutes the adhesin. Parenteral vaccination of sows with an F4-containing vaccine protects the suckling piglets against neonatal F4+ ETEC-induced diarrhoea, but no commercial (mucosal) vaccine exists against F4+ ETEC-induced weaning diarrhoea. To develop a vaccine, a bioactive F4-receptor (F4R) binding FaeG molecule is required that binds to the F4R following oral immunization and induces a FaeG-specific immune response. The present study reports the altered binding of the FaeG-specific monoclonal antibody IMM01 with bioactive versus non-bioactive F4 fimbrial adhesin FaeG. The correlation of altered IMM01 binding with altered FaeG bioactivity permits the use of an IMM01-based ELISA as a fast, specific and sensitive in vitro selection for potent F4 or (recombinant) FaeG antigen formulations, useful in an F4+ ETEC vaccine.

Postpartum maternal corticosterone decreases maternal and neonatal antibody levels and increases the susceptibility of newborn mice to herpes simplex virus-associated mortality

The effects of corticosterone on the transmammary transfer of herpes simplex virus (HSV)-specific antibody and the ability of the neonate to survive HSV-2 infection were assessed. Increased postpartum maternal corticosterone reduced the levels of total and HSV-specific IgG in the serum and milk of mothers. Neonates nursed by these mothers received increased levels of corticosterone and decreased levels of total and HSV-specific IgG. Accordingly, these neonates were more susceptible to HSV-2-associated mortality; however, survival was restored through passive immunization with HSV-specific antibody. These studies demonstrate that postpartum elevations in corticosterone compromise a mother's ability to provide protective antibody to their offspring.

The effect of abrupt weaning of suckler calves on the plasma concentrations of cortisol, catecholamines, leukocytes, acute-phase proteins and in vitro interferon-gamma production

The objective of this study was to examine the effect of abrupt weaning (inclusive of social group disruption and maternal separation) on the physiological mediators of stress and measures of immune function. Thirty-six male and 36 female calves (Limousin and Charolais crosses), habituated to handling, were blocked by sex, weight, and breed of dam and randomly assigned, within block, to either a control or abruptly weaned group. Animals were separated into the respective treatment groups at 0 h. Calves were bled at -168, 6 (males only), 24, 48, and 168 h after weaning, and the behavioral reaction of calves to handling was scored. Cortisol, catecholamine (not sampled at -168 h), acute-phase protein concentrations, and in vitro interferon-gamma production and neutrophil:lymphocyte ratio were measured. The effects of weaning, calf sex, time, and their respective interactions were described. Disruption of the established social group at 0 h increased (P < 0.001) the plasma cortisol concentration and neutrophil:lymphocyte ratio and decreased the leukocyte concentration (P < 0.001) and the in vitro interferon-gamma response to the mitogen concanavalin-A (P < 0.001) and keyhole limpet hemocyanin (P < 0.001) for weaned and control animals compared with -168 h. There was no effect of weaning or sex on the behavioral reaction of calves to handling. Plasma cortisol and adrenaline concentrations were not affected by weaning or sex. Plasma noradrenaline concentration was influenced by weaning x sex (P < 0.05) and time x sex (P < 0.05). The response increased for male calves with weaning and increased with each sampling time after weaning. For heifers, the response was not affected by weaning and plasma concentrations decreased at 168 h after weaning. There was no effect of weaning or sex on leukocyte concentration. The neutrophil:lymphocyte ratio increased after weaning (P < 0.01) and was affected by sex (P < 0.05). Weaning decreased (P < 0.05) the in vitro interferon-gamma response to the antigen keyhole limpet hemocyanin. There was a time x weaning x sex (P < 0.05) interaction for fibrinogen concentration but no effect of treatment on haptoglobin concentration. Abrupt weaning increased plasma cortisol and noradrenaline concentrations that were accompanied by attenuation of in vitro interferon-gamma production to novel mitogen and antigen complexes up to 7 d after weaning.

The Role of the 19-kDa Region of Merozoite Surface Protein 1 and Whole-Parasite-Specific Maternal Antibodies in Directing Neonatal Pups’ Responses to Rodent Malaria Infection

Maternal Abs generated as a result of prior exposure to infectious agents such as the malaria parasite are transferred from the mother through the placenta to the fetus. Numerous studies have attributed the resistance to malaria infection observed in neonates and infants up to 6 mo of age to the presence of maternally derived Abs. However, recent studies have produced conflicting results suggesting that alternative protective mechanisms may be responsible. Although the presence of maternally derived Abs in the infant is not disputed, their exact role in the infant is unknown. Even less clear is the effect that maternally derived Abs, if generated in response to vaccination, may have on the infant's ability to respond to malaria infection. Studies on mouse pups were performed to determine the role of the 19-kDa region of merozoite surface protein 1 (MSP1(19)) and Plasmodium yoelii-specific Abs in neonatal malaria infection and to examine their effect on the development of a specific immune response in the pup. It was shown that P. yoelii- and MSP1(19)-specific Abs transferred to the pup from the mother act to suppress the growth of the parasite in the pup. However, the maternally derived Abs interfered with the development of the pups' own Ab response to the parasite by altering the fine specificity of the response. These results suggest that immunizing women of child-bearing age with a malaria vaccine candidate such as MSP1(19) would not prevent the infant from producing Abs in response to malaria infection, but it may affect the region of the Ag to which it responds.

Health status and risk factors associated with failure of passive transfer of immunity in newborn beef calves in Québec

Risk factors associated with failure of passive transfer of immunity (FPT) were evaluated among newborn beef calves in Québec. Physical examination was performed on calves born of a normal calving and blood samples were collected for determination of health status and measurement of serum concentration of immunoglobulin (Ig) G1. Of 225 calves, from 45 herds, 19% showed FPT (serum IgG1 concentration < 10.0 g/L). Calves born in a stanchion-stall were more likely to show FPT (OR: 10.2). Calves bottle-fed colostrum were less at risk for FPT (OR: 0.06). Calf gender, month of birth, dam parity, and dam body condition score were not associated with FPT. No association was detected between FPT and health status. Special care should be given to calves born from cows in a stanchion-stall to ensure adequate colostrum intake. Failure of passive transfer of immunity should be considered with other risk factors when investigating morbidity.

Neutrophil function and plasma opsonic capacity in colostrum-fed and colostrum-deprived neonatal kittens

OBJECTIVE

To determine whether passive transfer of IgG in neonatal kittens affects plasma opsonic capacity and neutrophil phagocytic and oxidative burst responses to bacteria in vitro.

ANIMALS

22 kittens from 6 specific pathogen-free queens.

PROCEDURE

Kittens were randomized at birth into the following treatment groups: colostrum-fed, colostrum-deprived, or colostrum-deprived supplemented with feline or equine IgG. Blood samples were collected at intervals from birth to 56 days of age. Plasma IgG concentrations were determined by radial immunodiffusion assay. Neutrophil function was assessed by a flow cytometry assay providing simultaneous measurement of bacteria-induced phagocytosis and oxidative burst. The opsonic capacity of kitten plasma was determined in an opsonophagocytosis assay with bacteria incubated in untreated or heat-inactivated plasma.

RESULTS

Among treatment groups, there were no significant differences in neutrophil phagocytic and oxidative burst responses to bacteria or opsonic capacity of plasma. In all samples of plasma, inactivation of complement and other heat-labile opsonins significantly reduced the opsonic capacity. Plasma IgG concentrations in kittens did not correlate with neutrophil function or plasma opsonic capacity before or after inactivation of complement.

CONCLUSIONS AND CLINICAL RELEVANCE

The plasma opsonic capacity and neutrophil phagocytic and oxidative burst responses in vitro of kittens receiving passive transfer of IgG via colostrum intake or IgG supplementation and those deprived of colostrum were similar. The alternate complement pathway or other heat-labile opsonins may be more important than IgG in bacterial opsonization and phagocytosis.

Effects of prenatal stress on corticosteroid receptors and monoamine concentrations in limbic areas of suckling piglets (Sus scrofa) at different ages

The present study was conducted in order to reveal the effects of prenatal stress on the central stress regulation in domestic pigs by measuring changes in corticosteroid receptor binding and monoamine concentrations in different limbic brain regions. Pregnant sows were subjected to a restraint stress for 5 min daily during the last 5 weeks of gestation. Maternal stress resulted in a significantly higher number of glucocorticoid receptors in the hippocampus, but decreased glucocorticoid receptors in the hypothalamus of the offspring at the first postnatal day. No alterations of hippocampal mineralocorticoid receptors were found. There was also no significant effect of prenatal stress on the brain monoamine concentrations. Prenatally stressed piglets showed lower basal plasma cortisol and increased corticosteroid binding globulin concentrations at the third postnatal day indicating decreased free cortisol concentrations after birth. Morbidity and mortality during the suckling period were significantly increased in prenatally stressed litters, as shown by a higher frequency of diseased and died piglets per litter. In conclusion, the results indicate that in pigs restraint stress during late gestation affects the ontogeny of the foetal neuroendocrine feedback system with consequences for the regulation of the hypothalamo-pituitary-adrenal function and the vitality of the offspring.

Blood and colostrum/milk serum gamma-glutamyltransferase activity as a predictor of passive transfer status in lambs

The importance of blood and colostrum/milk serum gamma-glutamyl transferase (gamma-GT) enzyme activity was evaluated to assess passive transfer status in healthy lambs. Thirty Akkaraman sheep (3-6 years old) were used which had normal pregnancy period and the same conditions, and the age of the lambs ranged between 0 and 15 days. Blood and colostrum/milk samples were collected from sheep and lambs after birth, before suckling (0) and after on 1st, 3rd, 7th and 15th days. Serum immunoglobulin G (IgG) concentration was determined by the use of Single Radial Immunodiffusion method. Serum gamma-GT activity was measured, using a commercially available kit in blood and colostrum/milk samples. Correlations were carried out between immunoglobulin and gamma-GT levels. Regression models (simple and multiple) were calculated with significant data. Linear correlation was determined between colostrum/milk gamma-GT activity and IgG concentrations and between serum gamma-GT activity and IgG concentrations in lambs on the 0 day. (r: 0.607, P: 0.001), 1st (r: 0.768, P: 0.001) and the 3rd (r: 0.603, P: 0.001) days and on the 1st (r: 0.637, P: 0.001) and 3rd (r: 0.478, P: 0.012) days in the experiment, respectively. Multivariate regression models were developed to estimate sample IgG concentration. Serum and colostrum/milk IgG concentration could be predicted using the formula: lamb serum IgG = 825 + 0.688 (lamb gamma-GT) + 52 (days); colostrum/milk IgG = 832 + 0.505 (colostrum/milk gamma-GT) - 167 (days). The regression models were moderately accurate in predicting serum IgG concentration (R2 = 0.51) and colostrum/milk IgG concentration (R2 = 0.55). Test sensitivity and positive predictive values for serum gamma-GT enzyme activity were found to be 96 and 100% and for colostrum/milk gamma-GT enzyme activity were found to be 100 and 68% to prediction IgG concentration. Serum and colostrum/milk gamma-GT activity can be used to assess passive transfer status of lambs. Along with this, regression models used to calculate serum and colostrum/milk gamma-GT activities found to be useful to estimate sample IgG concentration. The use of serum and colostrum/milk gamma-GT enzyme activity was found useful especially after birth on the 0, 1st and 3rd days.

Feline immunodeficiency virus is concentrated in milk early in lactation

We studied mother-to-offspring transmission of feline immunodeficiency virus (FIV), focusing on milk-borne virus transmission in order to assess its similarities to perinatal HIV transmission. We also attempted to evaluate the influence of intragestational treatment with 9-[2-(phosphono-methoxy)-propyl]adenine (PMPA) on virus transmission to offspring. Eleven female cats (queens), chronically infected with FIV-B-2542 and bred to an FIV-negative male, produced a total of 25 viable and 18 nonviable term kittens. Overall, the vertical transmission rate by untreated queens was 22%, similar to that for HIV, which unfortunately precluded adequate assessment of PMPA efficacy. However, at delivery 9 of 10 queens (90%) had higher viral RNA loads in milk (4 x 10(4) to 4 x 10(8) viral copies/ml) than in plasma (5 x 10(3) to 2.5 x 10(6) viral copies/ml). Conversely, 10 of 11 queens (91%) had lower proviral loads in milk cells (0 to 10(2) proviral copies/microg DNA) than blood cells (10(2) to 10(4) proviral copies/microg DNA). Thus, FIV is concentrated in early milk despite relatively low proviral loads in milk cells, suggesting that virus may be actively secreted by the mammary gland for dissemination to offspring. FIV provides a model for the study of milk-borne lentivirus transmission and assessment of strategies to reduce postnatal HIV vertical transmission.

Immunoglobulin derived from bovine plasma as a replacement for colostrum in newborn lambs

Newborn lambs (n = 45) at the Agricultural Research Institute of Northern Ireland were fed either 50 grams of commercial lamb milk replacer or 50 grams of commercial colostrum replacer (bovine origin) in 200 ml of water four times during the first 24 hours of life or were given ad libitum access to the ewe. Total plasma protein at 24 hours of age was highest in lambs allowed to suckle the ewe (76.9 g/L). However, by 14 days of age, there were no differences in plasma protein levels among the three treatments. Bovine IgG was measured in lambs fed colostrum replacer and ovine IgG was measured in other lambs. Mean plasma IgG concentrations at 24 hours of age were 0.7 (milk replacer), 18.0 (colostrum replacer), and 26.6 (dam's milk) g/L. Bovine IgG administered orally to newborn lambs was adequately absorbed, and circulating IgG concentrations were sufficiently maintained throughout this study.

Lambs prevented from suckling their mothers display behavioral, immune and endocrine disturbances

The aim of the experiment was to assess the effects of either maternal deprivation or prevented suckling on lambs. Thirty Comisana lambs were assigned to a control dam-suckled group (DS) and two test groups of 10 each. Test lambs were maintained with their mothers 24 to 30 h after parturition and subsequently offered ewe milk from buckets: EM lambs were separated from their mothers, while EM+D animals were reared with their dams but suckling was denied by covering ewe udders with juta bags. Behavioral, immune and cortisol responses of lambs were assessed throughout the experiment. EM+D lambs spent less time (P<.001) on investigative behavior compared to the two other groups. When isolated in a novel environment, EM+D lambs exhibited a shorter duration of movement (P<.01) and a longer latency time compared to DS and EM lambs (P<.001 and P<.05, respectively) as well as a higher number of bleats (P<.01) than EM lambs. EM+D lambs also displayed higher (P<.001) plasma cortisol levels than the other two groups when isolated at 4 days of age. When subjected to discrimination tests, EM+D lambs spent less time near their companions (P<.01) than EM lambs and took a longer time to reach their pen mates (P<.01) than DS and EM lambs. EM+D lambs displayed reduced growth (P<.001) compared to DS animals during the 0-7 and 8-14-day periods. We conclude that frustration arising from maternal feeding deprivation results in altered endocrine and behavioral responses and reduced growth suggesting emotional disturbances of lambs.

Uptake of colostral immunoglobulins by the compromised newborn farm animal

Neonatal mortality is very high in farm animals (approximately 10%) and disease resistance is greatly influenced by an adequate passive immunisation just after birth. In piglets, foals, calves and lambs, the intestinal absorption of immunoglobulins from their mother's colostrum occurs mainly by a non-specific endocytosis of macromolecules, but the details of the absorption process, and the mechanisms regulating its cessation after 1-2 days of colostrum exposure, remain poorly understood. In both normal and 'compromised' (premature, growth-retarded, hypoxic, lethargic) newborn farm animals, the intestinal capacity to absorb macromolecules is influenced by both diet- and animal-related factors. Thus, macromolecule uptake is severely reduced in response to premature birth and when macromolecules are to be absorbed from diets other than species-specific colostrum. On the other hand, fetal growth retardation, in vitro embryo production, or a stressful birth process are unlikely to reduce the ability of the intestine to absorb immunoglobulins from colostrum. More knowledge about the diet- and animal-related factors affecting intestinal immunoglobulin uptake will improve the clinical care of 'compromised' newborn farm animals. The present text gives a brief introduction to the process of intestinal immunoglobulin absorption in large farm animals and describe some recent results from the author's own studies in pigs, calves and lambs.

Generation of adult-like antibody avidity profiles after early-life immunization with protein vaccines

The capacity to induce high-avidity antibodies following early-life immunization has long been questioned, and the possibility of inducing such antibodies soon after birth is a recognized goal for a number of vaccination strategies. Therefore, we assessed the capacity to develop high-avidity antibodies to peptidic vaccines in 1-week-old BALB/c mice. The dynamics of the generation of antibody molecules of increasing avidity were analyzed on circulating serum antibodies and, where feasible, at the single-cell level on spleen and bone marrow antibody-secreting cells. Two alum-adsorbed protein-based human vaccines, tetanus toxoid (TT) and pertussis toxin, induced neonatal antibody responses with adult-like avidity profiles. This was confirmed at the level of spleen and bone marrow ASC. In contrast, immunization with TT-P30, a 21-mer synthetic peptide containing a TT-immunodominant epitope, trinitrophenyl hapten (TNP) conjugated to ovalbumin or TNP conjugated to Ficoll, induced a much lower avidity profile in early life than in adults. These observations indicate that in murine models the avidity maturation of T cell-dependent antibody responses induced by structurally complex protein vaccines can be fully elicited after early life immunization, as opposed to the maturation of responses induced with short peptides or hapten-based vaccines.

Use of adult cat serum to correct failure of passive transfer in kittens

OBJECTIVE

To evaluate the use of adult cat serum as an immunoglobulin supplement in kittens with failure of passive transfer.

DESIGN

Randomized controlled study.

ANIMALS

11 specific pathogen-free queens and their 43 kittens.

PROCEDURE

Kittens were removed from the queens at birth, prior to suckling colostrum, and randomly assigned to 1 of 4 groups: colostrum-deprived, colostrum-fed, colostrum-deprived and administration of pooled adult cat serum i.p., and colostrum-deprived and administration of pooled adult serum s.c.. Colostrum-fed kittens were returned to the queen and allowed to suckle normally. Colostrum-deprived kittens were isolated from the queen and fed a kitten milk replacer for 2 days to prevent absorption of colostral IgG. All colostrum-deprived kittens were returned to the queen on day 3. Serum IgG concentrations were measured by radial immunodiffusion in the kittens at birth and 2 days and 1, 2, 4, 6, and 8 weeks after birth.

RESULTS

None of the kittens had detectable serum IgG at birth. Both i.p. and s.c. administration of adult cat serum resulted in peak serum IgG concentrations equivalent to those in kittens that suckled normally. Untreated colostrum-deprived kittens did not achieve serum IgG concentrations comparable to those for kittens in the other groups until 6 weeks of age.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that adult cat serum may be used as an immunoglobulin supplement in colostrum-deprived kittens. Although the minimum concentration of IgG necessary to protect kittens from infection is unknown, concentrations achieved were comparable to those in kittens that suckled normally.

Passive transfer of maternal immunoglobulin isotype antibodies against tetanus and influenza and their effect on the response of foals to vaccination

Influenza and tetanus-specific antibodies of the IgG sub-isotypes are posively transferred to foals via colostrum and inhibit their response to inactivated influenza vaccines and tetanus toxoid. High titres of influenza antibodies of IgGa and IgGb subisotypes and tetanus antibodies of the IgGa, IgGb and IgG(T) subisotypes were detected in postsucking serum samples collected from foals born to mares that had received booster doses of multicomponent vaccines during the last 2 months of gestation. Thereafter, titres declined in an exponential manner but were still detectable in all foals at age 26 weeks, regardless of whether they had been vaccinated prior to age 26 weeks. Mean +/- s.e. half-life of decline of influenza IgGa antibodies (27.0 +/- 2.3 days) was significantly shorter than that of influenza IgGb antibodies (39.1 +/- 2.7 days; P<0.005). Tetanus IgGa and IgGb antibodies declined with half-lives of 28.8 +/- 3.0 and 34.8 +/- 5.1 days, respectively. Titres of tetanus IgG(T) antibodies were substantially higher than those of influenza IgG(T) antibodies in postsucking samples and remained so through age 26 weeks, declining with a half-life of approximately 35 days. Postsucking titres of tetanus and influenza antibodies of the IgA isotype were low and declined rapidly to undetectable levels. Yearlings showed significant increases in titre of influenza IgGa, IgGb and IgG(T) subisotype antibodies but no increase in influenza IgA antibodies in response to 2 doses of multicomponent vaccines containing tetanus toxoid and inactivated influenza A-1 and A-2 antigens. Yearlings also showed strong tetanus IgGa, IgGb and IgG(T) subisotype responses to one dose of vaccine and a substantial further rise in titre in response to administration of a second dose 3 weeks later, but failed to show an increase in titre of tetanus IgA antibodies. The influenza and tetanus IgGa, IgGb and IgG(T) subisotype responses of 6-month-old foals to vaccination followed the same pattern as those shown by yearlings but titres were generally lower. In contrast, 3-month-old foals failed to show increases in titre of either influenza or tetanus IgG subisotypes in response to 2 doses of vaccine and generally needed 1-3 additional booster doses of vaccine to achieve titres similar to those achieved by yearlings after 2 doses. Based on the finding that maternal antibodies exert a significant inhibitory effect on the response of foals to tetanus toxoid and inactivated influenza antigens, it is recommended that primary immunisation of foals born to vaccinated mares should not commence before age 6 months.

Immune modulation in suckling rat pups by a growth factor extract derived from milk whey

Oral tolerance to foreign enteral antigens is not fully developed in early neonatal life. Epidemiological evidence supports a role for maternal milk in the development of immune responses, including oral tolerance. Formula fed infants have an increased susceptibility to food allergy and the later development of autoimmune disease. This may relate to the lack in infant formula of growth factors found in maternal milk. Bovine milk contains proteins, growth factors and cytokines. Various studies have outlined the immune modulating potential of bovine milk-derived products. Fractionated whey extracts have therapeutic potential in disease states where there is an excessive inflammatory reaction, and disease preventive potential for infants who are not breast-fed. We have shown that daily oral administration of a growth factor-enriched fraction from milk whey to naturally suckling rat pups between days 4-9 postnatal can down-regulate immune activation to a specific orally administered food antigen, ovalbumin, assessed by lymphocyte proliferation. In addition, non-specific down-regulation in the intestine was observed as assessed by the expression of MHC I. Treatment of rat pups with whey extract at the time of oral sensitisation to ovalbumin also resulted in an increased secretion of TGF-beta into the culture supernatant of spleen cells incubated with specific antigen. TGF-beta is an immuno-down-regulatory cytokine involved in tolerance induction. Immune modulation by extracts derived from milk whey could be of potential benefit for formula-fed and pre-term infants in reducing susceptibility to inappropriate activation to food antigens.

The influence of parenterally administered alpha-tocopheryl acetate to sows on the vitamin E status of the sows and suckling piglets and piglets after weaning

The main aim of the study was to test if parenteral administration of alpha-tocopheryl acetate twice before farrowing and weaning could increase the vitamin E status of the newborn piglets and piglets after weaning. In Trial I eight sows were given 1.5 g alpha-tocopheryl acetate intramuscularly 7 and 2 days before farrowing. Eight sows were untreated controls. The experimental sows had a higher vitamin E concentration in colostrum than the controls. No significant difference between the groups existed in milk at weaning. The serum vitamin E concentration in the experimental piglets 2 and 5 days after farrowing was higher than in the controls. Fifteen days after farrowing the difference between the groups had nearly disappeared. The serum vitamin E concentration in the piglets in the control group was higher during the first days after farrowing than later, and was gradually reduced until at least 2 weeks after weaning. In Trial II, eight sows were given 1.5 g of alpha-tocopheryl acetate 7 and 2 days before weaning of their piglets. They had higher vitamin E concentrations in milk and serum than untreated control sows at weaning. The increase did not, however, influence the serum vitamin E concentration of the piglets. The lowest concentration of vitamin E in serum of the piglets was reached at 45 days after farrowing. The activity of the selenium-dependent enzyme glutathione peroxidase in the serum of piglets was very low during the first week of life in both groups despite the fact that the sows' feed had been supplemented with 0.35 mg selenium/kg. This indicates that the selenium status of newborn piglets might be more critical for their health than their vitamin E status.

[Serum gammaglobulin titer in goat kids after colostrum administration: effect of commercial colostrum replacers]

Seven commercially available colostrum replacers were tested for their ability to substitute for goat colostrum as a source of gammaglobulin for goat kids. One hundred kids were fed with goat colostrum or colostrum replacer after separation from their mothers at birth. Blood samples were taken from ten kids at birth, and from all kids at 48 hours after birth. Samples were used to measure the total protein content and gammaglobulin concentration of serum. Kids fed with goat colostrum had higher gammaglobulin concentrations than newborn kids or kids fed with replacer. For three replacers, the gammaglobulin concentrations were the same as those of newborn kids. For three other replacers, the gammablobulin concentrations were similar but higher than those of newborn kids. For one replacer, the levels of gammaglobulin were higher than those of in newborn kids and higher than those measured after feeding of the other replacers. None of the replacers was an adequate substitute for goat colostrum as a source of gammaglobulins.

Serum immunoglobulin G concentrations in calves fed fresh and frozen colostrum

OBJECTIVE

To determine whether serum IgG concentrations in neonatal calves are adversely affected by short-term frozen storage of colostrum.

DESIGN

Prospective study.

SAMPLE POPULATION

Experiment 1 consisted of 10 pairs of Holstein calves (n = 20) fed matched aliquots of either fresh (n = 10) or frozen and thawed (10) colostrum. In experiment 2, 26 Holstein calves were fed either fresh (n = 13) or frozen and thawed (n = 13) colostrum.

PROCEDURE

Experiment 1 consisted of calves resulting from observed parturitions; calves were randomly assigned to treatment groups (fresh or frozen and thawed colostrum) in pairs. Calves were fed 4 L aliquots of colostrum via oroesophageal intubation at 3 hours of age. Serum IgG concentrations at 2 days of age were compared between the 2 groups by use of a paired t-test. Experiment 2 consisted of calves resulting from observed parturitions; calves were randomly assigned to treatment groups (fresh or frozen and thawed colostrum). Calves were fed 4 L aliquots of colostrum via oroesophageal intubation at 3 hours of age. Regression analysis was used to determine whether calf serum IgG concentration was a function of colostral IgG concentration and colostrum storage group.

RESULTS

Significant differences were not observed between the 2 groups in experiment 1. No significant relationship was observed between colostrum storage group and serum IgG concentration in experiment 2. The model that best predicted serum IgG concentrations accounted for 20% of the variability in serum IgG concentration.

CONCLUSION AND CLINICAL RELEVANCE

Frozen colostrum is an adequate source of IgG for calves.

The role of the Type I interferon response in the resistance of mice to filovirus infection

Adult immunocompetent mice inoculated with Ebola (EBO) or Marburg (MBG) virus do not become ill. A suckling-mouse-passaged variant of EBO Zaire ’76 (‘mouse-adapted EBO-Z’) causes rapidly lethal infection in adult mice after intraperitoneal (i.p.) inoculation, but does not cause apparent disease when inoculated subcutaneously (s.c.). A series of experiments showed that both forms of resistance to infection are mediated by the Type I interferon response. Mice lacking the cell-surface IFN-α/β receptor died within a week after inoculation of EBO-Z ’76, EBO Sudan, MBG Musoke or MBG Ravn, or after s.c. challenge with mouse-adapted EBO-Z. EBO Reston and EBO Ivory Coast did not cause illness, but immunized the mice against subsequent challenge with mouse-adapted EBO-Z. Normal adult mice treated with antibodies against murine IFN-α/β could also be lethally infected with i.p.-inoculated EBO-Z ’76 or EBO Sudan and with s.c.-inoculated mouse-adapted EBO-Z. Severe combined immunodeficient (SCID) mice became ill 3–4 weeks after inoculation with EBO-Z ’76, EBO Sudan or MBG Ravn, but not the other viruses. Treatment with anti-IFN-α/β antibodies markedly accelerated the course of EBO-Z ’76 infection. Antibody treatment blocked the effect of a potent antiviral drug, 3-deazaneplanocin A, indicating that successful filovirus therapy may require the active participation of the Type I IFN response. Mice lacking an IFN-α/β response resemble primates in their susceptibility to rapidly progressive, overwhelming filovirus infection. The outcome of filovirus transfer between animal species appears to be determined by interactions between the virus and the innate immune response.

[Serum gamma globulin concentration in goat kids after colostrum administration: effect of time of administration, volume and type of colostrum]

In this study, which was performed on a Dutch dairy goat farm, several aspects of the administration of colostrum to new-born goat kids were examined. Time of colostrum administration and amount and type of colostrum administered were compared. Effectiveness was measured as total serum protein content and gamma globulin fraction. No significant differences in serum gamma globulin titre were observed between kids that received colostrum at 30 or 60-90 minutes post partum, respectively. Titres were significantly lower in kids that received 100 ml of colostrum instead of 150-200 ml. The effect of sheep colostrum replacer or cow colostrum was also examined. Gamma globulin titres were significantly high with goat colostrum than with cow colostrum or sheep colostrum replacer, and titres were higher with cow colostrum than with sheep colostrum replacer. Based on the results of this experiment, the following protocol is suggested for colostrum administration to goat kids: single administration of 150-200 ml of goat colostrum within 90 minutes of birth. Use of cow colostrum is not advised because it may lead to transmission of paratuberculosis. Use of sheep colostrum replacer as a source of passive immunity is not recommended.

Immunological protection of the vulnerable marsupial pouch young: two periods of immune transfer during lactation in Trichosurus vulpecula (brushtail possum)

Marsupial young are born with an underdeveloped immune system and are dependent upon passively acquired immune protection provided by the mother's milk. Colostrum and milk samples were collected from the brushtail possum throughout lactation and the concentration of secretory IgA (sIgA), IgG and transferrin was determined by Western blotting. Two periods of immune transfer were identified. The first, a colostral phase, occurs immediately after birth and involves sIgA, IgG and transferrin. During the early lactation stage, pouch young receive milk of a unique composition as they undergo developmental changes in the pouch that occur in utero for eutherian mammals. At the end of this external gestation, the composition of the milk changes (switch phase) to resemble that of eutherian mammals in the late lactation phase. The second transfer of immunity consists of IgG and transferrin, and occurs during the switch phase prior to maturation of the immune response.

Development of the immune system and immunological protection in marsupial pouch young

At birth the tissues of marsupial immune system are underdeveloped. The young animal is not immunocompetent. Histological and immunohistochemical studies of pouch young epithelial tissues provide a clear picture of tissue development but the timing of onset of immunocompetence awaits definition. The survival of the neonatal marsupial in a microbially rich environment is dependent on maternal strategies, including immunoglobulin transfer via milk and, in some species, prenatally via the yolk sac placenta. It is also likely that pouch secretions play a role. This review summarizes our current knowledge of the pathway of immunological development in marsupials and the protection and threats afforded by the pouch environment.