Breast Milk-Derived Antibodies Impair Vaccine Immunity in Suckling Mice.

Breast milk confers multiple benefits to the neonate, including passive immunity against multiple microorganisms via Abs. However, it remains unclear whether breast milk-derived Abs affect vaccine-induced immunity in the neonate. We evaluated in C57BL/6 and BALB/c mice whether breastfeeding from an mRNA-SARS-CoV-2-vaccinated dam affects vaccine-induced immunity in neonate mice. Using an experimental model that allows the distinction of maternal Abs and neonate Abs based on their allotype, we show that breastfeeding from an immune dam is associated with reduced vaccine immunity in the neonate. Importantly, mice that breastfed from an immune dam showed reduced numbers of plasma cells after vaccination, relative to mice that breastfed from a naive dam. Our subsequent studies using an mRNA-luciferase reporter system show that passive transfer of Abs through breastfeeding accelerates the clearance of vaccine Ag in suckling mice, resulting in reduced Ag availability. Altogether, maternal Abs transferred through breast milk can protect against infectious microorganisms, but they may also interfere with the neonate's response to vaccination by accelerating the clearance of vaccine Ag. These findings are important for understanding the effects of maternal Abs on the neonate's response to vaccines and may provide insights for improving neonatal vaccines.

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-1ß, 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-1ß, IL-4, IL-6, and IFN-γ, and, possibly, in the indirect assessment of some indices in lactating sows, including IgA, IL-1ß, IL-4, IL-6, IL-8, IFN-γ, or Pig-MAP.

Leptin and adiponectin supplementation modifies mesenteric lymph node lymphocyte composition and functionality in suckling rats.

At birth, when immune responses are insufficient, there begins the development of the defence capability against pathogens. Leptin and adiponectin, adipokines that are present in breast milk, have been shown to play a role in the regulation of immune responses. We report here, for the first time, the influence of in vivo adipokine supplementation on the intestinal immune system in early life. Suckling Wistar rats were daily supplemented with leptin (0·7 µg/kg per d, n 36) or adiponectin (35 µg/kg per d, n 36) during the suckling period. The lymphocyte composition, proliferation and cytokine secretion from mesenteric lymph node lymphocytes (on days 14 and 21), as well as intestinal IgA and IgM concentration (day 21), were evaluated. At day 14, leptin supplementation significantly increased the TCRαß + cell proportion in mesenteric lymph nodes, in particular owing to an increase in the TCRαß + CD8+ cell population. Moreover, the leptin or adiponectin supplementation promoted the early development CD8+ cells, with adiponectin being the only adipokine capable of enhancing the lymphoproliferative ability at the end of the suckling period. Although leptin decreased intestinal IgA concentration, it had a trophic effect on the intestine in early life. Supplementation of both adipokines modulated the cytokine profile during (day 14) and at the end (day 21) of the suckling period. These results suggest that leptin and adiponectin during suckling play a role in the development of mucosal immunity in early life.

Preweaned heifer management on US dairy operations: Part I. Descriptive characteristics of preweaned heifer raising practices.

The objective of this study was to describe preweaned dairy heifer calf management practices on dairy operations across the United States that were used to analyze factors associated with colostrum quality and passive transfer, Cryptosporidium and Giardia, morbidity and mortality, and average daily gain. This study included 104 dairy operations in 13 states that participated in the National Animal Health Monitoring System's Dairy 2014 calf component study. This 18-mo longitudinal study focused on dairy heifer calves from birth to weaning, and data were collected on 2,545 heifer calves. Descriptive statistics were generated regarding colostrum feeding, preweaning housing, milk feeding and consumption, growth, morbidity and mortality, and weaning practices. The majority of calves enrolled were Holsteins (89.4%). Over half the calves (63.2%) enrolled in the study received the majority of their colostrum via bottle; however, 22.1% of calves from 51.0% of operations received colostrum via suckling from their dams. For all calves, the mean time to the first colostrum feeding was 2.8 h, and the average amount of colostrum at the first feeding was 2.9 L, with 4.5 L provided in the first 24 h. The mean serum IgG of all calves was 21.7 g/L; however, 76.0% of operations had at least 1 calf with failure of passive transfer of immunity with a serum IgG below 10 g/L. The majority of calves in the study were housed individually (86.6%). Nonetheless, 20.2% of operations housed some calves in groups, representing 13.4% of all calves. Approximately one-half of the calves in the study (52.3%) were dehorned or disbudded during the preweaning period, with only 27.8% of these calves receiving analgesics or anesthetics during the procedure. Whole or waste milk was the liquid diet type fed to 40.1% of calves, and milk replacer was fed to 34.8% of calves. A combination of milk and milk replacer was fed to 25.1% of calves. Calves, on average, were fed 2.6 L per feeding and fed 2.6 times/d, resulting in a total of 5.6 L of liquid diet fed per day. The mean average daily gain for all calves enrolled in the study was 0.7 kg/d. Fecal samples were collected and almost all operations had at least 1 calf positive for Cryptosporidium (94.2%) or Giardia (99.0%), and 84.6% of operations had calves that tested positive for both Cryptosporidium and Giardia. Over one-third of calves (38.1%) had at least one morbidity event during the preweaning period and the mortality rate was 5.0%. The mean age at weaning was 65.7 d. This study provides an update on dairy heifer raising practices in the United States.

Increased frequency of porcine epidemic diarrhea virus shedding and lesions in suckling pigs compared to nursery pigs and protective immunity in nursery pigs after homologous re-challenge.

Porcine epidemic diarrhea virus (PEDV) causes enteric disease in pigs and spreads rapidly after entering naïve pig populations. The objectives were to (1) compare the disease course following inoculation with PEDV isolate US/Colorado/2013 in naïve 10 day and 8 week-old pigs, and (2) contrast the naïve response to homologous challenge in 8 week-old pigs. Pigs were randomly assigned into group 1 (n = 40, no PEDV exposure), group 2 (n = 43, PEDV inoculation at 10 days of age) and group 3 (n = 48, PEDV inoculation at 8 weeks of age). Thirty-three group 2 pigs received a homologous challenge at 8 weeks of age. Following primary or secondary inoculation, 3-10 pigs were euthanized at days post-inoculation (dpi) 1, 2, 3, 7 or 14. Clinical signs were more pronounced in 10 day-old pigs compared to 8 week-old pigs at dpi 2 and 3, a higher number of 10 day-old pigs shed PEDV RNA in feces compared to 8 week-old pigs. Typical severe atrophic enteritis of PEDV infection was observed at dpi 3 in both age groups, and at dpi 4 and 14 fecal shedding patterns were also similar. While both age groups had seroconverted to PEDV by dpi 14, IgG levels were higher in 8 week-old pigs. PEDV IgA antibodies were detected in feces of approximately 50% of the pigs at dpi 44. In homologous challenged pigs, no clinical signs or lesions were found, and PEDV fecal shedding was restricted to less than 10% of the pigs indicating the existence of homologous protection 44 days after initial PEDV exposure.

Feeding a diet devoid of choline to lactating rodents restricts growth and lymphocyte development in offspring.

The nutrient choline is necessary for membrane synthesis and methyl donation, with increased requirements during lactation. The majority of immune development occurs postnatally, but the importance of choline supply for immune development during this critical period is unknown. The objective of this study was to determine the importance of maternal supply of choline during suckling on immune function in their offspring among rodents. At parturition, Sprague-Dawley dams were randomised to either a choline-devoid (ChD; n 7) or choline-sufficient (ChS, 1 g/kg choline; n 10) diet with their offspring euthanised at 3 weeks of age. In a second experiment, offspring were weaned to a ChS diet until 10 weeks of age (ChD-ChS, n 5 and ChS-ChS, n 9). Splenocytes were isolated, and parameters of immune function were measured. The ChD offspring received less choline in breast milk and had lower final body and organ weight compared with ChS offspring (P<0·05), but this effect disappeared by week 10 with choline supplementation from weaning. ChD offspring had a higher proportion of T cells expressing activation markers (CD71 or CD28) and a lower proportion of total B cells (CD45RA+) and responded less to T cell stimulation (lower stimulation index and less IFN-γ production) ex vivo (P<0·05). ChD-ChS offspring had a lower proportion of total and activated CD4+ T cells, and produced less IL-6 after mitogen stimulation compared with cells from ChS-ChS (P<0·05). Our study suggests that choline is required in the suckling diet to facilitate immune development, and choline deprivation during this critical period has lasting effects on T cell function later in life.

The content of docosahexaenoic acid in the maternal diet differentially affects the immune response in lactating dams and suckled offspring.

PURPOSE: The objective of this study was to determine the effect of feeding a maternal diet supplemented with docosahexaenoic acid (DHA) while also containing adequate amounts of arachidonic acid on immune system development and function in suckled offspring and lactating rats. METHODS: Sprague-Dawley dams were randomized to one of the two nutritionally adequate experimental diets 24-48 h prior to parturition: control diet (N = 12, 0 % DHA) or high DHA diet (N = 8, 0.9 % DHA of total fatty acids). Diets were fed throughout the lactating/suckling period (21 days), and then, dams and pups were terminated, and immune cell phenotypes and cytokine production by mitogen- or ovalbumin-stimulated splenocytes were measured. RESULTS: Feeding dams a high DHA diet resulted in a higher proportion of 18:3n-3, 22:5n-3 and 22:6n-3 found in pup's stomach content (breast milk; P < 0.01). Feeding the high DHA diet had no impact on growth parameters or the ex vivo cytokine production by mitogen-stimulated splenocytes in both dams and pups. There was a higher proportion of OX12+CD80+ cells and a lower production of TGF-ß by splenocytes after ovalbumin stimulation in pups from dams fed the DHA diet (both P < 0.05) while maintaining a similar IL-2 production. LPS-stimulated splenocytes from dams fed the high DHA diet produced more TNF-α versus control diet (P < 0.05). CONCLUSIONS: Overall, our results suggest that DHA supplementation in the maternal diet does not change the immune response to mitogens but positively affects the activation of B cells as well as the response to a potential food antigen upon challenge in suckled offspring.

Gestation and breastfeeding in schistosomotic mothers differently modulate the immune response of adult offspring to postnatal Schistosoma mansoni infection.

Schistosoma mansoni antigens in the early life alter homologous and heterologous immunity during postnatal infections. We evaluate the immunity to parasite antigens and ovalbumin (OA) in adult mice born/suckled by schistosomotic mothers. Newborns were divided into: born (BIM), suckled (SIM) or born/suckled (BSIM) in schistosomotic mothers, and animals from noninfected mothers (control). When adults, the mice were infected and compared the hepatic granuloma size and cellularity. Some animals were OA + adjuvant immunised. We evaluated hypersensitivity reactions (HR), antibodies levels (IgG1/IgG2a) anti-soluble egg antigen and anti-soluble worm antigen preparation, and anti-OA, cytokine production, and CD4+FoxP3+T-cells by splenocytes. Compared to control group, BIM mice showed a greater quantity of granulomas and collagen deposition, whereas SIM and BSIM presented smaller granulomas. BSIM group exhibited the lowest levels of anti-parasite antibodies. For anti-OA immunity, immediate HR was suppressed in all groups, with greater intensity in SIM mice accompanied of the remarkable level of basal CD4+FoxP3+T-cells. BIM and SIM groups produced less interleukin (IL)-4 and interferon (IFN)-g. In BSIM, there was higher production of IL-10 and IFN-g, but lower levels of IL-4 and CD4+FoxP3+T-cells. Thus, pregnancy in schistosomotic mothers intensified hepatic fibrosis, whereas breastfeeding diminished granulomas in descendants. Separately, pregnancy and breastfeeding could suppress heterologous immunity; however, when combined, the responses could be partially restored in infected descendants.

Passive transfer of maternal immunity in the dromedary (Camelus dromedarius), involvement of heavy chain antibodies.

In many mammalian species, newborns are agammaglobulinemic; thus, colostrum and milk are the main sources of early protective antibodies. These antibodies are produced in the mother's serum and transferred to mammalian glands a few days before parturition. Here, we have studied the transfer of immunity from a she-camel immunized with human serum albumin (HSA) to her calf via colostrum and milk. Our results show that HSA-specific antibodies are produced in the mother's serum and are subsequently transferred to her colostrum. These specific antibodies are then transferred by suckling to the calf. The calf serum did not contain HSA-reactive antibodies at parturition and before the first feed, after suckling, a rise in reactivity was observed peaking at 24 h postpartum. The involvement of heavy chain antibodies (HCAbs) in the process of immunity transfer was also examined, and it was found that they were also transferred from the colostrum to the calf serum like conventional antibodies.

Effect of L-arginine on HSP70 expression in liver in weanling piglets.

BACKGROUND: This study was conducted to evaluate the effects of L-arginine (Arg) on photomicrographs and HSP70 expression in the liver of weanling piglets. Twelve healthy Landrace × Yorkshire piglets that had been weaned at 21 d (average body weight 5.56 ± 0.51 kg) were randomly divided into a control group and an Arg group (6 g/kg feed). At age 28 d, all of the piglets were slaughtered to obtain liver samples to determine HSP70 expression by real-time PCR, western blot and immunohistochemistry. RESULTS: The results showed that, compared to control piglets, treatment with Arg decreased inflammatory reactions caused by weaning. The immunohistochemical localization of HSP70 in liver revealed strong expression in the Arg group. Arg increased HSP70 mRNA and HSP70 expression in the liver (P < 0.05). CONCLUSIONS: These findings suggest that dietary supplementation with Arg could maintain liver health by inducing HSP70 expression in weanling piglets.

Effect of feeding maternal colostrum or plasma-derived or colostrum-derived colostrum replacer on passive transfer of immunity, health, and performance of preweaning heifer calves.

The objective of this study was to evaluate the effect of feeding maternal colostrum (MC), a plasma-derived (PDCR) or colostrum-derived colostrum replacer (CDCR) on passive transfer of immunity, health, and performance of preweaning heifer calves. Preplanned contrasts were performed for MC versus CR (PDCR combined with CDCR) and PDCR versus CDCR. At birth, calves were randomly assigned to 1 of 3 treatment groups: MC (n=49), 3.8L of maternal colostrum; PDCR (n=49), 550 g (1 dose; 150 g of IgG) of a PDCR; or CDCR (n=49), 470 g (1 dose; 100g IgG) of a CDCR. The best total protein cutoff for determining passive transfer was >5.2, 5.6, and 5.1g/dL for MC, PDCR, and CDCR, respectively. Serum total protein was greater for calves fed MC (mean ± SE; 6.14 ± 0.11 g/dL) than for calves fed PDCR (5.29 ± 0.11 g/dL) and CDCR (5.27 ± 0.11 g/dL). Serum IgG concentrations were greater for calves fed MC (2,098 ± 108 g/dL) than for calves fed PDCR (927 ± 107 g/dL) or CDCR (1,139 ± 108 g/dL). Apparent efficiency of absorption was greater for CDCR than PDCR (38.8 ± 3.0 vs. 21.6 ± 3.0%). Adequate passive transfer was greatest for MC (91.8%), followed by CDCR (49%) and PDCR (28.6%). Calves fed MC had greater weaning weights and body weight gain than calves fed CR. Morbidity was lower for calves fed MC (46.9%) than for calves fed PDCR (71.4%) or CDCR (67.3%). Calves fed MC tended to have lower mortality than calves fed CR. Given the conditions of this trial, feeding 3.8L of MC was superior to feeding one dose of CR. Further research is needed to evaluate calf performance when a higher dose of CR is fed.

Multiple-dose therapy with bovine colostrum confers significant protection against diarrhea in a mouse model of human rotavirus-induced gastrointestinal disease.

Rotavirus is the most important etiologic agent of severe gastroenteritis. Previously, we reported that skimmed and concentrated bovine late colostrum (SCBLC) obtained from normal unimmunized cows at 6 to 7d after parturition effectively prevented against human rotavirus (HRV)-induced severe gastroenteritis in vivo, when administered as a single dose 60 min before viral inoculation. In the present study, we examined the efficacy of multiple administrations of SCBLC at smaller dosages after viral inoculation in vivo. We demonstrate that multiple administrations within 24h after virus inoculation resulted in earlier recovery from diarrheal symptoms, in an administration frequency-dependent manner. Furthermore, we investigated whether isolated IgG anti-HRV activity in SCBLC was equivalent to that of IgG isolated from bovine mature milk as measured by in vitro activity assays. We found that IgG-containing fractions from SCBLC and mature milk exhibited approximately the same level of anti-HRV activity. We concluded that the SCBLC contains a high level of IgG against HRV-induced severe gastroenteritis, which will be possible to use in protective effects in immunocompromised hosts, such as children and the elderly. Multiple doses of SCBLC during the early stages of infection or lower dosage of SCBLC given as a single dose both resulted in relief of diarrheal symptoms.

Effect of calf starter feeding on gut microbial diversity and expression of genes involved in host immune responses and tight junctions in dairy calves during weaning transition.

Calf starters are usually offered to dairy calves to facilitate the weaning process, however, the effect of solid feed consumption on gut health has not been well studied. This study aimed to investigate the effect of calf starter feeding on the gut bacterial community and mucosal immune functions in dairy calves during weaning transition. Mucosal tissue and digesta samples were collected from rumen, jejunum, ileum, cecum, and colon upon slaughtering of calves (n=8) after feeding the experimental diets [milk replacer (MR) or milk replacer + calf starter (MR+S)] for 6 wk. Expression of toll-like receptor (TLR) 10 was downregulated along the gut, whereas TLR2 in colon and TLR6 along the gut were upregulated in MR+S-fed calves compared with MR-fed calves. Ileal TLR9 and TLR10 showed higher expression compared with the other regions regardless of the diet. Peptidoglycan recognition protein 1 demonstrated a diet- and gut-regional dependent expression pattern, whereas ß-defensin did not. The diet and gut region also affected the expression of tight junction-regulating genes claudin 4 and occludin. Bacterial diversity tended to be different between the 2 diets, whereas the bacterial density was different among gut regions and sample type. The present study revealed that changes in bacterial diversity, expression of genes encoding host mucosal immune responses, and barrier functions were associated with the MR+S diet, and suggests that solid feed consumption may alter gut microbiome and host mucosal functions during weaning transition.

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.

Myelin basic protein serum factor. An endogenous neuroantigen influencing development of experimental allergic encephalomyelitis in Lewis rats.

Age-related concentrations of myelin basic protein serum factor (MBP-SF), an endogenous neuroantigen detected and quantitated by inhibition of binding of rat myelin basic protein (RMBP) antibody with 125I-RMBP reagent antigen and immunochemically indistinguishable from native RMBP in this respect, reach peak levels as high as 21 ng/microliter among 2-3-wk-old normal suckling Lewis rats. Levels then progressively decline to low, usually undetectable levels of less than or equal to 0.6 ng/microliter MBP-equivalents in adult animals by 7 wk of age. MBP-SF levels are inversely related to the age-related increasing capacity of maturing Lewis rats to develop experimental allergic encephalomyelitis (EAE) after sensitization to MBP of syngeneic, but not xenogeneic, origin. MBP-SF appears to be an endogenous neuroimmunoregulatory product of potential importance for immunologic tolerance to autologous RMBP in Lewis rats.

Transport of immunoglobulins from serum into colostrum.

Oligomeric, J-chain-containing immunoglobulins were observed to be transferred selectively from serum into colostrum. These studies suggest that, in the case of the mammary gland secretion, a significant role for extraglandular synthesis of IgA merits consideration. Thus, for example, colostrum may contain antibodies synthesized locally as well as antibodies synthesized in the much larger lymphoid tissues such as the gut lamina propria.

Adoptive transfer studies demonstrating the antiviral effect of natural killer cells in vivo.

We carried out adoptive transfer studies to determine the role of natural killer (NK) cells in resistance to murine cytomegalovirus (MCMV) and lymphocytic choriomeningitis virus (LCMV). We transferred leukocytes from adult mice into suckling mice 1 d before injecting them with virus. Resistance was measured by enhancement of survival and reduction of virus multiplication in the spleens of recipient mice. The phenotype of the cell population capable of mediating resistance to MCMV was that of a nylon wool-nonadherent, asialo GM1+, NK 1.2+, Ly-5+, Thy-1-, Ia-, low density lymphocyte; this is the phenotype of an NK cell. Cloned NK cells, but not cloned T cells, provided resistance to MCMV in suckling mice. Cloned NK cells also provided resistance to MCMV in irradiated adult mice, and antibody to asialo GM1, which depletes NK cell activity in vivo, enhanced the synthesis of MCMV in athymic nude mice. Neither adult leukocytes nor cloned NK cells influenced LCMV synthesis in suckling mice. We conclude that a general property of NK cells may be to provide natural resistance to virus infections, and that NK cells can protect mice from MCMV but not from LCMV.

The postnatal maternal environment affects autoimmune disease susceptibility in A/J mice.

The postnatal maternal environment is known to increase susceptibility to a number of autoimmune diseases. Here we asked whether the postnatal maternal environment could influence autoimmune disease development to day 3 thymectomy (d3tx)-induced autoimmune ovarian disease (AOD) and experimental allergic encephalomyelitis (EAE) in cross-fostered A/J and B6 mice. A/J pups foster-nursed by B6 mothers exhibit an increase in autoimmune disease development while cross-fostering B6 pups on A/J mothers did not alter their susceptibility. The increase in AOD incidence seen in foster-nursed d3tx A/J mice correlated with a decrease in the total number of CD4(+) T cells in the lymph nodes of these animals. Analysis of the cellular composition in the milk revealed that B6 mice shed significantly more maternally derived lymphocytes into their milk compared to A/J mothers. These data suggest that there are maternally derived postnatal factors that influence the development of autoimmune disease in A/J mice.

Neonatal tolerance under breastfeeding influence: the presence of allergen and transforming growth factor-beta in breast milk protects the progeny from allergic asthma.

Once the umbilical cord has been cut, immunologists have often looked at the neonate as an entity that develops on its own. For years, breast milk was considered mainly as a source of nutrients for the developing child. The extensive observations that breastfeeding affords protection toward infectious diseases and could reduce by more than the half the mortality rate because of common infections have added another key role to breastfeeding. This protection relies in great part on the passive transfer through breast milk of high amounts of microbe-specific immunoglobulins that compensate for the deficiency of immunoglobulins synthesis during the first year of life. Here, we will present and discuss our data showing how breast milk can actively shape the immune response of the progeny, particularly in the context of allergic disease. Indeed, our data obtained in a mouse model suggest that the protection attributed to breastfeeding toward asthma development might rely on immune tolerance induction. For this to occur, the mother mice needed to be exposed to the allergen by aerosol or oral route during the lactation period, which resulted into the transfer of the allergen to breast milk. The presence of the allergen together with transforming growth factor-beta in breast milk was necessary and sufficient to induce the development of regulatory T lymphocytes in the progeny and their protection from asthma development. If confirmed in human beings, this study may suggest new strategies for asthma prevention such as deliberate exposure of mother to allergens during breastfeeding and qualitative modification of artificial milks.

Genome wide association study of passive immunity and disease traits in beef-suckler and dairy calves on Irish farms.

Calves with lower concentrations of immunoglobulin G (IgG) in their blood, have a greater risk of developing diseases. There is a lack of knowledge on genetic markers known to be associated with immunological variability or disease resistance. Therefore, the objective of this study was to identify SNP markers associated with passive immunity measures (serum IgG, serum protein, albumin, globulin and total protein concentrations, total solids Brix percentage, zinc sulphate turbidity units) and disease (pneumonia, diarrhoea, crude illness) traits in Irish commercial beef-suckler and dairy calves through genome wide association studies (GWAS). Genotyping was performed on DNA samples from beef-suckler (n = 698) and dairy (n = 1178) calves, using the IDBv3 chip. Heritability of passive immunity associated traits (range 0.02-0.22) and the disease traits (range 0.03-0.20) were low-to-moderate. Twenty-five and fifteen SNPs approached genome wide significance (P < 5 × 10-5) for the passive immunity and the disease traits, respectively. One SNP "ARS-BFGL-BAC-27914" reached Bonferroni genome wide significance (P < 1.15 × 10-6) for an association with serum IgG concentration in beef calves. Further work will evaluate these SNPs in larger cattle populations and assess their contribution to genomic selection breeding strategies, aimed towards producing more disease resistant livestock.