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Life history theory assumes there are trade-offs between competing functions such as reproduction and immunity. Although well studied in birds, studies of the trade-offs between reproduction and immunity in small mammals are scarce. Here we examined whether reduced immunity is a consequence of reproductive effort in lactating Brandt's voles (Lasiopodomys brandtii). Specifically, we tested the effects of lactation on immune function (Experiment I). The results showed that food intake and resting metabolic rate (RMR) were higher in lactating voles (6≤ litter size ≤8) than that in non-reproductive voles. Contrary to our expectation, lactating voles also had higher levels of serum total Immunoglobulin G (IgG) and anti-keyhole limpet hemocyanin (KLH) IgG and no change in phytohemagglutinin (PHA) response and anti-KLH Immunoglobulin M (IgM) compared with non-reproductive voles, suggesting improved rather than reduced immune function. To further test the effect of differences in reproductive investment on immunity, we compared the responses between natural large (n≥8) and small litter size (n≤6) (Experiment II) and manipulated large (11-13) and small litter size (2-3) (Experiment III). During peak lactation, acquired immunity (PHA response, anti-KLH IgG and anti-KLH IgM) was not significantly different between voles raising large or small litters in both experiments, despite the measured difference in reproductive investment (greater litter size, litter mass, RMR and food intake in the voles raising larger litters). Total IgG was higher in voles with natural large litter size than those with natural small litter size, but decreased in the enlarged litter size group compared with control and reduced group. Our results showed that immune function is not suppressed to compensate the high energy demands during lactation in Brandt's voles and contrasting the situation in birds, is unlikely to be an important aspect mediating the trade-off between reproduction and survival.

It has been hypothesized that the maternal immune response to infection may influence fetal brain development and lead to schizophrenia. Animal experimentation has supported this notion by demonstrating altered sensorimotor gating (prepulse inhibition, PPI) in adult rats prenatally exposed to an immune challenge. In the present study, pregnant rats were exposed to the bacterial endotoxin lipopolysaccharide (LPS) throughout gestation and the offspring were examined by evaluating the PPI, dopaminergic function, brain protein expression and cytokine serum levels from weaning to late adulthood. Prenatal LPS exposure induced a deficit in PPI that emerged at ‘puberty’ and that persisted throughout adult life. This prenatal insult caused age-specific changes in accumbal dopamine levels and in synaptophysin expression in the frontal cortex. Moreover, serum cytokine levels were altered in an age- and cytokine-dependent manner. Here we show that prenatal LPS administration throughout pregnancy causes maturation-dependent PPI deficits and age-dependent alterations in dopamine activity, as well as in synaptophysin expression and cytokine levels.

To investigate the influence of maternal Se supply and plane of nutrition on lamb morbidity, mortality, and passive transfer of IgG, pregnant ewe lambs were used in 2 experiments with 2 x 3 factorial treatment arrangements. Supplementation of Se began at breeding and was either adequate Se (ASe, 9.5 µg/kg of BW) or high Se (HSe, 81.8 µg/kg of BW) in Exp. 1 or ASe (11.5 µg/kg of BW) or HSe (77.0 µg/kg of BW) in Exp. 2. On d 50 or 40 of gestation for Exp. 1 or 2, respectively, ewes were assigned randomly to 1 of 3 nutritional planes: 60% (RES), 100% (control, CON), or 140% (HI) of NRC requirements. This resulted in the following treatments: ASe-RES, ASe-CON, ASe-HI, HSe-RES, HSe-CON, and HSe-HI. Upon parturition, lambs were separated from their dams and serum samples obtained. Lambs were fed artificial colostrum for the first 20 h and then placed on milk replacer and grain pellets until completion of the study (Exp. 1, 57 d; Exp. 2, 21 d). Twenty-four hours after parturition, lamb serum samples were collected for IgG analysis. All lambs were reared similarly and morbidity and mortality assessed. Main effects were considered significant when P ≤ 0.05. In Exp. 1, there was a Se x plane of nutrition interaction (P ≤ 0.01) for lamb morbidity from birth to weaning and for 24-h IgG concentration. Lambs from ASe-RES and HSe-HI ewes were treated more frequently (P < 0.01) for respiratory and gastrointestinal disease, and lambs from HSe-HI ewes had the smallest (P < 0.01) 24-h serum IgG concentration. In Exp. 1, lambs from HI ewes also had the greatest (P < 0.01) mortality rates from birth to weaning compared with lambs from CON and RES ewes. In Exp. 2, there was an effect (P < 0.01) of maternal plane of nutrition with lambs from RES ewes having increased 24-h IgG compared with lambs from CON and HI ewes. There was no effect of maternal Se supplementation on lamb 24-h IgG in Exp. 2; however, there was a Se x plane of nutrition interaction (P < 0.01) for morbidity. From birth to 21 d of age, lambs from ASe-CON ewes had fewer (P < 0.01) treatment days compared with lambs from any of the other treatment groups. There also tended (P = 0.08) to be an effect of maternal Se supplementation on lamb mortality with increased mortality observed in lambs from HSe ewes. Results from the studies show a restricted maternal plane of nutrition can increase lamb serum IgG concentration. Selenium results were not consistent between the 2 experiments and may be due to differences in maternal Se.

Majorera goat kids (n=200) were used to evaluate the effects of litter size, birth body weight, sex, and suckling duration on serum IgG concentrations. Kids were assigned to 1 of 3 experimental groups: litter size and sex were equally distributed in each group. In the first group, kids (n=67) stayed with their dams for 24h; in the second group, kids (n=66) stayed with their dams for 48h; and in the third group, kids (n=67) stayed with their dams for 120h. Blood samples were obtained every 24h for 5 d, and serum IgG concentration was measured using radial immunodiffusion. In litter sizes of 1 to 2 kids, IgG blood serum concentration was significantly higher (18.30±5.40mg/mL) than in litters of 3 kids (9.85±4.23mg/mL). Kid sex did not affect IgG blood serum concentrations. Suckling duration did not affect kid serum IgG concentrations. In conclusion, kids with low birth body weight (<2.8kg) or from litters of 3 may need special attention. If newborn goat kids are allowed to suckle colostrum for at least 24h from their dams, this seems to be sufficient time to ingest enough IgG from colostrum to achieve an adequate serum IgG concentration and passive immune protection to avoid failure of passive immune transfer.

Japanese Encephalitis Virus (JEV) is considered an important reproductive pathogen in pigs. Most studies of the reproductive impact of JEV have been conducted in areas where the disease occurs in seasonal epidemics. In this study, the associations between seropositivity for JEV, measured with an IgG ELISA, and the number of piglets born alive and stillborn were investigated in a tropical area endemic for JEV in Vietnam. Sixty percent of sows from four farms in the Mekong delta of Vietnam were seropositive to JEV and the Odds Ratio for a sow being infected was highest (6.4) in sows above 3.5 years (95% confidence interval 2.2–18.3). There was an association between increasing Optical Density (OD) values from the ELISA and the number of stillborn piglets in sows less than 1.5 years, but no effect of seropositivity could be shown when all sows were studied. OD values had an effect ( p  = 0.04) on the number of piglets born alive in the statistical analysis only when interacting with the effect of the breeds. An increase in mean OD value of the herd was correlated ( p  < 0.0001) with an increase in the number of piglets born alive. In this study, there was evidence of a negative association between seropositivity for JEV and the reproductive performance only in sows less than 1.5 years in endemic areas. This could be explained by a year-round infection with the virus, which would lead to immunity in many gilts before their first pregnancy. This, in turn, may imply that JEV infection in pigs is of minor importance for the reproductive performance in endemic areas.

Two experiments were conducted to evaluate the effects of the immunization of gilts against ovarian steroids on ovulation rate and litter size. In Exp. 1, gilts (n = five gilts/treatment) at 165+/-1.6 d of age were immunized against either carrier (Control), androstenedione, or 17alpha-hydroxyprogesterone. Age at puberty and estrous cycle length averaged 208+/-5.5 (P = 0.67) and 20.3+/-2.8 d (P = 0.41), respectively, and were not affected by treatment. The androstenedione- and 17alpha-hydroxyprogesterone immunized gilts had higher (P < 0.02) ovulation rates than Controls (14.2, 14.2, and 11.4+/-0.8, respectively). Total pigs born (P = 0.66) and pigs born live (P = 0.65) for the androstenedione-treated group were not different from Controls. Gestation length was not different (P = 0.36) between any of the treatments and the Controls (115+/-0.9 d). Procedures used in Exp. 2 were similar to those in Exp. 1, except that only Control (n= 18) and 17alpha-hydroxyprogesterone (n = 16) treatments were included and only litter size at farrowing was measured. Total pigs and pigs born live were higher in the 17a-hydroxyprogesterone-treated gilts than in the Controls (12.6 vs 10.5+/-0.6, P < 0.02; and 11.4 vs 9.2+/-0.6; P < 0.01, respectively). Data from this study indicate that litter size in gilts can be increased by immunization against 17alpha-hydroxyprogesterone.

Inhibin is a gonadal hormone that inhibits the release of follicle stimulating hormone (FSH) from the anterior pituitary gland. The objective of this study was to determine whether active immunization of male and female rats against inhibin rich, steroid-free bovine follicular fluid would increase inhibin antibody titre, onset of female puberty, pregnancy rate, litter size, testis weights, testosterone concentration and serum FSH. Immunization of rats with steroid free bovine follicular fluid stimulated production of anti-inhibin antibodies that immunoneutralized endogenous inhibins and increased levels of circulating FSH in immunized males. Inhibin immunoneutralization resulted in early vaginal opening in immunized females compared with controls and pregnancy rates were increased when immunized female rats were mated with immunized males. However, serum testosterone, testis weights and potential litter size remained unchanged. We conclude that methods to immunoneutralize inhibin may have merit as therapeutic procedures to enhance reproductive performance in domestic animals.

Neonatal infections are a leading cause of mortality in dogs, with up to 30% of puppies dying within the first 3 weeks of life. During this critical period of immune development, protection is highly dependent on maternal antibodies (MatAbs) transferred across the placenta and via colostrum. Despite the critical importance of this transfer, limited information is available regarding the biological or clinical factors that determine its magnitude, whether specific antibodies are preferentially transferred, or how these processes vary across a broad population of dogs. To quantify and explore the determinants of MatAb transfer in dogs, we analyzed matched maternal serum, cord blood, and colostrum samples collected from 44 client-owned dams undergoing cesarean section at a university veterinary hospital. Total immunoglobulin G (IgG) and virus-specific antibodies against canine parvovirus (CPV) and canine distemper virus (CDV) were analyzed. We also evaluated the influence of maternal factors, including age, breed, body weight, parity, and litter size, on MatAb transfer efficiency. Across this diverse population, we observed limited transplacental transfer of MatAbs (4.5%-6% of the maternal titer), consistent with previous studies and as expected given the endotheliochorial placenta of dogs. In contrast, virus-specific IgG was highly enriched in colostrum, with 10.7-fold (CPV) and 8.1-fold (CDV) increases relative to serum. Transfer efficiency was significantly greater for virus-specific antibodies than for total IgG (3.2-fold), suggesting selective enrichment of antiviral antibodies during colostrogenesis. Maternal serum antibody titer emerged as the primary factor influencing antibody transfer efficiency. These findings provide the most comprehensive quantification to date of MatAb transfer routes in dogs, revealing preferential transfer of virus-specific IgG to colostrum and highlighting the crucial role of colostrum intake in neonatal immunity. This work establishes a foundation for identifying antibody characteristics that influence MatAb transfer efficiency and reinforces the importance of ensuring that dams have adequate titers of virus-specific IgG prior to breeding.

The present study was conducted to evaluate the impact of dietary fully oxidised β-carotene (OxBC, C40H60O15) supplementation during the perinatal period on immune status and productivity in a sow model. At day 85 of pregnancy, 150 sows were allocated to one of three dietary treatments with fifty sows per treatment. The three experimental diets were supplemented with 0, 4 or 8 mg/kg OxBC in the basal diet. The feeding trial was conducted from gestation day 85 until day 21 of lactation. Dietary OxBC supplementation greatly enhanced colostrum IgM, IgA and IgG levels, and the IgM and IgG content of 14-d milk. Dietary OxBC supplementation decreased the TNF-α and IL-8 levels in colostrum, as well as the TNF-α and IL-18 levels in 14-d milk. There was also a tendency towards an increase in the soluble CD14 level in 14-d milk. Although dietary treatments did not affect average daily feed intake nor backfat thickness loss during lactation, dietary OxBC supplementation tended to enhance litter weight and individual piglet weight at weaning. There was a trend towards increased lactose concentration in 14-d milk with increasing dietary OxBC. It is concluded that dietary supplementation with OxBC during the perinatal period enhances the lactose concentration of sow milk and the immune status of sows, which is reflected by improved cytokine status and immunoglobulin concentrations in colostrum and milk, and thus tending to increase litter weight and individual piglet weight at weaning. The results also provide a scientific nutritional reference for perinatal mothers due to the biological similarity between pigs and humans.

Rift Valley fever virus (RVFV) causes significant disease in humans and livestock. Immunogenicity of candidate vaccines rMP-12 and RVax-1 show promise, but their placental tropism and potential effects on fetal outcomes remain incompletely understood, particularly across different animal models. Understanding species-specific placental replication is essential to optimize vaccine safety in pregnant populations. To evaluate the placental tropism and fetal outcomes of RVFV candidate vaccines rMP-12 and RVax-1 in pregnant Sprague–Dawley (SD) rats and C57BL/6 mice. Pregnant SD rats and C57BL/6 mice were vaccinated intramuscularly at embryonic day 14 (E14) with 1 × 105 or 1 × 106 PFU of rMP-12 or RVax-1. Viral replication in maternal, placental, and fetal tissues was assessed at E18 in rats and at E17 or E19–21 in mice using viral RNA quantification and antigen detection. Fetal outcomes, including litter size, placental histopathology, and fetal demise, were recorded. In rats, both vaccines showed minimal replication in placental and fetal tissues, indicating limited vertical transmission. In contrast, mice were more susceptible: viral RNA and antigens were detected in maternal livers, placentas, and fetal compartments. rMP-12–vaccinated mice showed reduced litter sizes and autolyzed placental tissues, whereas RVax-1–vaccinated mice exhibited fetal demise, with viral antigens detected in spongiotrophoblasts, syncytiotrophoblasts, and trophoblast giant cells of the junctional and labyrinth zones. RVFV vaccines rMP-12 and RVax-1 exhibit residual placental tropism in mice but minimal replication in rats, highlighting species-specific differences. Mouse models may be useful for studying placental tropism, and these findings inform future optimization of vaccine safety during pregnancy. •RVFV vaccines rMP-12 and RVax-1 showed minimal placental replication in rats.•Both vaccines replicated in mouse placentas, causing fetal demise in some cases.•Mouse model may be useful to study placental tropism of RVFV vaccines.