Revisão de literatura sobre os aspectos fisiológicos e nutricionais em bezerros alimentados com colostro acidificado / Literature review on physiological and nutritional aspects in calves fed acidified colostrum / Revisión de la literatura sobre aspectos fisiológicos y nutricionales en terneros alimentados con calostro acidificado

A colostragem é essencial para a saúde dos bezerros neonatos, uma vez que não há a transferência de imunidade através da placenta, ou seja, o contato inicial do organismo com anticorpos se dá através da primeira mamada, onde há transferência da imunidade passiva. Sendo assim, o objetivo do trabalho é revisar os benefícios da acidificação ou silagem do colostro para otimizar a conservação da dieta líquida em fazendas; analisar o impacto no desempenho de bezerros em comparação com o colostro tradicional refrigerado em aleitamentos convencionais. O volume ideal preconizado é, no mínimo, 10% do peso vivo do animal nas primeiras duas horas e mais 5% do peso vivo nas seis a oito horas seguintes a primeira ingestão, para que se obtenha um bom desenvolvimento durante o crescimento, caso contrário, a falta da administração do colostro nas primeiras horas de vida predispõe enfermidades, tais como pneumonia e diarreia, prejudicando assim a saúde e consequentemente o desempenho em relação a outros animais que receberam uma colostragem adequada. Problemas com a qualidade do colostro surgem devido ao armazenamento inadequado, especialmente em propriedades sem refrigeração. A falta de sistemas de congelamento resulta em administração de leite em temperatura ambiente por períodos prolongados, prejudicando assim a imunidade e nutrição dos bezerros durante a colostragem. Todavia, há alternativas para o problema tal como o fornecimento de silagem de colostro. Em alguns casos, o processo de acidificação demanda a adição de ácidos no leite, a fim de evitar o crescimento de microrganismos patogênicos. O principal aspecto positivo do leite acidificado é a manutenção em temperatura ambiente, ou seja, não há a necessidade de passar por processos de refrigeração.

Colostrum is essential for the health of newborn calves, since there is no transfer of immunity through the placenta, that is, the body's initial contact with antibodies occurs through the first feeding, where there is a transfer of passive immunity. Therefore, the objective of the work is to review the benefits of acidifying or colostrum silage to optimize the conservation of liquid diets on farms; analyze the impact on calf performance compared to traditional refrigerated colostrum in conventional sucklers. The recommended ideal volume is at least 10% of the animal's live weight in the first two hours and a further 5% of its live weight in the six to eight hours following the first ingestion, so that good development is achieved during growth, otherwise, the lack of colostrum administration in the first hours of life predisposes diseases, such as pneumonia and diarrhea, thus harming health and consequently performance in relation to other animals that received adequate colostrum. Problems with colostrum quality arise due to inadequate storage, especially in unrefrigerated properties. The lack of freezing systems results in milk being administered at room temperature for prolonged periods, thus damaging the calves immunity and nutrition during colostrum. However, there are alternatives to the problem such as the supply of colostrum silage. In some cases, the acidification process requires the addition of acids to the milk in order to prevent the growth of pathogenic microorganisms. The main positive aspect of acidified milk is that it remains at room temperature, that is, there is no need to undergo refrigeration processes.

El calostro es esencial para la salud de los terneros recién nacidos, ya que no existe transferencia de inmunidad a través de la placenta, es decir, el contacto inicial del cuerpo con los anticuerpos ocurre a través de la primera alimentación, donde existe una transferencia de inmunidad pasiva. Por lo tanto, el objetivo del trabajo es revisar los beneficios de acidificar o ensilar el calostro para optimizar la conservación de dietas líquidas en granjas; analizar el impacto en el rendimiento de los terneros en comparación con el calostro refrigerado tradicional en lechones convencionales. El volumen ideal recomendado es al menos el 10% del peso vivo del animal en las dos primeras horas y otro 5% de su peso vivo en las seis a ocho horas siguientes a la primera ingesta, para que se consiga un buen desarrollo durante el crecimiento, en caso contrario. la falta de administración de calostro en las primeras horas de vida predispone a enfermedades, como neumonía y diarrea, perjudicando la salud y consecuentemente el rendimiento en relación a otros animales que recibieron el calostro adecuado. Los problemas con la calidad del calostro surgen debido a un almacenamiento inadecuado, especialmente en propiedades no refrigeradas. La falta de sistemas de congelación provoca que la leche se administre a temperatura ambiente durante períodos prolongados, dañando así la inmunidad y la nutrición de los terneros durante el calostro. Sin embargo, existen alternativas al problema como el suministro de ensilaje de calostro. En algunos casos, el proceso de acidificación requiere la adición de ácidos a la leche para evitar el crecimiento de microorganismos patógenos. El principal aspecto positivo de la leche acidificada es que se mantiene a temperatura ambiente, es decir, no es necesario someterse a procesos de refrigeración.

Effect of Supplementation with Saccharomyces cerevisiae and ß-glucans to Mares During Late Gestation on Colostrum Quality and Passive Transfer of Immunity in Foals.

The objective of this study was to determine whether supplementation with Saccharomyces cerevisiae or ß-glucan, in the maternal diet during late pregnancy affects the concentration of total IgG in the colostrum of mares and influences the concentration of IgG in its foals. A total of 21 pregnant mares were used, aged 6±2 years, 3±1 pregnancies, 450±50kg in weight, and they were distributed into three groups: the control group (n=7); the S. cerevisiae group (n=7), which received 1010CFU of S. cerevisiae orally; and the ß-glucan group (n=7), which received 0.35g of ß-glucan orally. All groups started from the 300th day of their pregnancies until delivery. Samples of colostrum and serum from the mares were collected immediately after delivery. Blood samples from their foals were collected 12h after birth. The IgG measurement was performed using radial immunodiffusion. The results underwent a variance analysis. Higher concentrations of IgG were observed in the colostrum of mares that were supplemented with ß-glucans (74.14±15.25 g/L) when compared to the control group (53.80g±10.95g/L). Serum IgG concentrations of foals born to mares supplemented with Saccharomyces cerevisiae (11.57±5.05 g/L) showed a significant difference, with a higher concentration of IgG in the serum compared to the control group. Therefore, this study provides evidence that manipulation of the mares' diets in late gestation to add ß-glucan increased the IgG concentration in their colostrum. The addition of S. cerevisiae appears to improve the concentration of IgG in their foals within 12h after birth.

Colostrum management practices that improve the transfer of passive immunity in neonatal dairy calves: A scoping review.

The objective of this scoping review was to describe the literature on the characteristics and management practices of colostrum feeding and their associations with the level of transfer of passive immunity (TPI) in dairy calves. Observational and experimental studies were searched in 5 electronic databases and 3 conference proceedings. Two reviewers independently screened primary studies, either analytic observational or experimental studies written in English. Studies on dairy or dual-purpose calves with passive immunity analyzed by blood sampling between 1 to 9 days of age were included. All studies had to compare at least one colostrum intervention or risk factor and their association with passive immunity. Of the 3,675 initially identified studies, 256 were included in this synthesis. One hundred and ninety-five were controlled trials, 57 were cohort studies, and 4 were cross-sectional studies. The effect of colostral quantity at first feeding was investigated in 30 controlled studies including studies that were comparable to each other. The effect of colostral quality was explored in 24 controlled studies with inconsistent criteria used to define the quality. The effect of the timing of first feeding of colostrum was investigated in 21 controlled studies, where the timing of feeding ranged widely from immediately after birth to 60 h of age. Only 4 controlled studies evaluated the relationship between bacterial load in the colostrum and TPI in dairy calves. Of the 256 total studies, 222 assessed blood IgG concentration while 107 measured blood total protein concentration. We identified a gap in knowledge on the association between passive immunity in dairy calves and the bacterial load in colostrum, or the timing of harvesting colostrum from the dam. A possible quantitative synthesis could be conducted among the studies that evaluated colostral quantity at the first feeding in relation to TPI in dairy calves.

Efficacy of passive immunization in broiler chicks via an inactivated Escherichia coli autogenous vaccine administered to broiler breeder hens.

Avian pathogenic Escherichia coli (APEC) cause extra-intestinal infections called colibacillosis, which is the dominant bacterial disease in broilers. To date, given the diversity of APEC strains and the need for an acceptable level of protection in day-old chicks, no satisfactory commercial vaccine is available. As part of a French nationwide project, we selected three representative strains among several hundred APEC that cause colibacillosis disease. We first performed experiments to develop colibacillosis in vivo models, using an inoculum of 3 × 107 CFU of each E. coli strain per chick. Two APEC strains (19-381 and 19-383-M1) were found to be highly virulent for day-old chicks, whereas the third strain (19-385-M1) induced no mortality nor morbidity.We then produced an autogenous vaccine using the (Llyod, 1982; MaCQueen, 1967) 19-381 and 19-383-M1 APEC strains and a passive immunization trial was undertaken. Specific-pathogen-free Leghorn hens were vaccinated twice 2 weeks apart, the control group receiving a saline solution. The vaccinated and control hens exhibited no clinical signs, and egg production and fertility of both groups were similar. Fertile eggs were collected for 2 weeks after the second vaccination and chicks were obtained. After challenge with each APEC (19-381 and 19-383-M1), chicks appeared to be partially protected from infection with the 19-383-M1 strain, with 40% mortality compared with 80% for the non-vaccinated chicks. No protection was found when the chicks were challenged with the 19-381 strain. Now, further work is needed to consider some aspects: severity of the pathogen challenge model, persistence of the protection, number of APEC strains in the autogenous vaccine, choice of adjuvants, and heterologous protection by the vaccine made from strain 19-383-M1.RESEARCH HIGHLIGHTS Three APEC strains were characterized and selected to develop in vivo models of colibacillosis.A bivalent autogenous vaccine was produced and a passive immunization trial was carried out.Protection of chicks was demonstrated when challenged with the 19-383-M1 APEC strain (homologous challenge).Further work is needed in particular to evaluate the protection against heterologous challenge.

The transfer of passive immunity in calves born at pasture.

Calf and dam separation is an area of growing public interest, and timely separation is also a practical challenge for pastoral farmers to achieve for all calves. Very few studies have investigated the success of leaving calves with their dams in pastoral conditions, so this observational study assessed serum total protein (STP) in calves born at pasture and left to suckle from their dams for up to 24 h. It also investigated failure of transfer of passive immunity (FPT) once calves had been provided colostrum from the farmer and some factors that may contribute to the risk of FPT. Over 2 years, 8 farms (4 in the North Island, 4 in South Island of New Zealand) were involved in an observational study where cows and calves were observed for 24 h a day for 2 wk per farm. Observers recorded the time from birth to first suckling, number of suckling events, time of calf removal from the dam, and ambient temperature. Calves were blood sampled on arrival at housing, before receiving colostrum from the farmer (d 1), and again 2 d later (d 3) to test for STP concentration. On d 1, 689 calves had blood samples collected, at a median of 11.5 (interquartile range 5.6 to 19.2) hours postbirth. Of these, 283 calves [41.1%; 95% confidence interval (CI) 37.4 to 44.9%] had STP >52 g/L (proportion by farm ranged from 10 to 78%). On d 3, 680 blood samples were collected, of which 16.0% (95% CI 13.5 to 19.0) had FPT (STP ≤52 g/L) with proportion by farm ranging from 2.5 to 31.6%. The FPT risk at d 3 in calves that did not suckle before housing was 2.91 (95% CI 2.04 to 4.13) times the risk in calves that suckled. For every hour longer postbirth that it took for a calf to have its first suckling event, odds of FPT at d 3 increased by 1.21 (95% CI 1.08 to 1.36) times, and compared with calves that only suckled once, calves that suckled 2, 3-5, or >5 times had 0.42 (95% CI 0.15 to 0.99), 0.35 (95% CI 0.15 to 0.76), and 0.10 (95% CI 0.005 to 0.47) times the odds of FPT, respectively. For every 1-percentage-point increase in the Brix % of the colostrum, the odds of FPT decreased by 33% (95% CI 24- to 42). Calves that suckled in the paddock and were fed colostrum with ≥22% Brix had the highest STP, and lowest odds of FPT, of any suckling/Brix % combination. There was a trend for STP to be greater in calves that suckled in the paddock and fed <22% Brix compared with calves that did not suckle in the paddock and fed ≥22% Brix. However, the calves in the former group also tended to have a greater risk of FPT at d 3, and a greater STP variability. There were very large between-farm variabilities for rates of suckling, colostrum feeding, and FPT risk that urgently require further investigation for calves born at pasture.

Prevalence of failure of passive immunity transfer in Australian non-replacement dairy calves.

Failure of passive immunity transfer (FPIT) increases the risk of morbidity and mortality in dairy calves. The prevalence of FPIT in dairy calves has generally been reported to be high, with FPIT estimated to occur in 38%-42% of Australian dairy calves. However, the focus of previous studies has been on replacement heifer calves. Our aim was to assess the prevalence of FPIT in Victorian bobby calves (non-replacement dairy calves). We collected blood samples from 3608 bobby calves at three abattoirs at exsanguination, and measured serum total protein as an indicator of passive transfer. We found that 36% of bobby calves showed evidence of FPIT (serum total protein ≤52 g/L), and 50% of calves had poor or fair passive transfer (<58 g/L). When a subset of calves (from farms with more than five calves in the dataset) was analysed using a linear mixed model, Jersey calves and crossbred/other calves had an estimated 5.3 g/L and 5.1 g/L higher serum total protein concentration, respectively, than Holstein-Friesian calves (P < 0.001). Our results suggest that the prevalence of FPIT in bobby calves at abattoirs is similar to that reported in dairy heifer calves sampled on farms. A high prevalence of FPIT has implications for bobby calf morbidity and mortality, as well as calf viability and profitability for dairy-beef production.

Antibody activities in hyperimmune plasma against the Rhodococcus equi virulence -associated protein A or poly-N-acetyl glucosamine are associated with protection of foals against rhodococcal pneumonia.

The efficacy of transfusion with hyperimmune plasma (HIP) for preventing pneumonia caused by Rhodococcus equi remains ill-defined. Quarter Horse foals at 2 large breeding farms were randomly assigned to be transfused with 2 L of HIP from adult donors hyperimmunized either with R. equi (RE HIP) or a conjugate vaccine eliciting antibody to the surface polysaccharide ß-1→6-poly-N-acetyl glucosamine (PNAG HIP) within 24 hours of birth. Antibody activities against PNAG and the rhodococcal virulence-associated protein A (VapA), and to deposition of complement component 1q (C՛1q) onto PNAG were determined by ELISA, and then associated with either clinical pneumonia at Farm A (n = 119) or subclinical pneumonia at Farm B (n = 114). Data were analyzed using multivariable logistic regression. Among RE HIP-transfused foals, the odds of pneumonia were approximately 6-fold higher (P = 0.0005) among foals with VapA antibody activity ≤ the population median. Among PNAG HIP-transfused foals, the odds of pneumonia were approximately 3-fold (P = 0.0347) and 11-fold (P = 0.0034) higher for foals with antibody activities ≤ the population median for PNAG or C՛1q deposition, respectively. Results indicated that levels of activity of antibodies against R. equi antigens are correlates of protection against both subclinical and clinical R. equi pneumonia in field settings. Among PNAG HIP-transfused foals, activity of antibodies with C՛1q deposition (an indicator of functional antibodies) were a stronger predictor of protection than was PNAG antibody activity alone. Collectively, these findings suggest that the amount and activity of antibodies in HIP (i.e., plasma volume and/or antibody activity) is positively associated with protection against R. equi pneumonia in foals.

Donkey-derived anti-CDV IgG, as a passive immunotherapy agent, can effectively increase survival rates of the experimental CDV-infected dogs.

BACKGROUND: Humoral immunity plays an important role in the prevention of canine distemper. Anti-CD virus (CDV) antibody has strong antiviral activity and is widely used in the treatment of CD. However, with the increase of CD cases, the availability of therapeutic CD antibody fell short of the clinical needs. RESULTS: The high-titer antiserum with the high-titer neutralizing activity against CDV was obtained from the donkeys (Dezhou Donkey) immunized with the inactivated CDV vaccine. The donkey anti-CDV IgG was purified from the donkey serum, which was identified to significantly inhibit the CDV replication in the cultured Vero cells and effectively reduce the clinical symptoms and increase the survival rates (75%) of CDV-infected dogs (Shih-tzu Dog), similar to that treated with the dog-derived anti-CDV IgG. These results indicate that donkey-derived IgG is a potential substitute for dog-derived IgG to treat the CD in clinic. CONCLUSIONS: Administration of donkey-derived anti-CDV IgG can ameliorate clinical symptoms and inhibit virus replication, thereby increasing the survival of CDV-infected dogs. This study opens up a new source of therapeutic antibody for CD treatment.

Effect of postpartum collection time and colostrum quality on passive transfer of immunity, performance, and small intestinal development in preweaning calves.

This study evaluated the effects of postpartum collection time and quality of colostrum fed to calves on the failure of passive transfer, growth, and small intestine development in the first 5 wk of life. Newborn calves (Holstein-Friesian × Jersey) were identified at birth and collected either early (E; within 12 h postpartum; n = 20) or late (L; 18-24 h postpartum; n = 20) and fed either high-quality colostrum [HQC, first milking colostrum with Brix% = 23 ± standard deviation (SD) 2] or low-quality colostrum (LQC, mixed colostrum and transition milk with Brix% = 12 ± 1) to create 4 treatments: E-HQC, E-LQC, L-HQC, and L-LQC (n = 10/treatment). After collection, calves (body weight = 32.3 ± 4.6 kg/calf) were fed either HQC or LQC (7.5% of their arrival body weight per feed) for the first 3 (L calves) or 4 feedings (E calves). All calves were then managed and fed similarly using automatic feeders which recorded individual intake of milk replacer and calf starter. Blood samples were taken at d 1 (after collection from dams but before colostrum feeding), 4, 14, and 35 of age to analyze selected metabolites. All calves were killed at d 35 ± 2 of age and histomorphology of duodenum, jejunum, and ileum was evaluated. At collection, 75% of E calves and 58% of L calves had serum total protein ≤52 g/L. At d 4 of age, calves fed HQC had greater serum total protein than calves fed LQC; however, failure of passive transfer (serum total protein ≤52 g/L) incidence did not differ between HQC and LQC. Collection time did not affect the scouring duration, but the amount of electrolyte used to treat sick calves was lower in L versus E calves, whereas feeding HQC versus LQC lowered both the scouring duration and electrolyte use to treat sick calves. Calves fed HQC had a greater total surface area of the duodenum (+23%) and jejunum (+17%) compared with LQC calves. Duodenal crypts were deeper in E-LQC calves than E-HQC and L-HQC calves, whereas L-LQC calves were intermediate. Villus height to crypt depth ratio in duodenum, jejunum, and ileum was greater in HQC than LQC calves. A trend toward greater average daily gain was observed in HQC versus LQC calves (667 vs. 590 g/d) but the average daily gain was not influenced by collection time. Serum IGF-1 at d 4 was higher in HQC versus LQC calves and this might have contributed to greater average daily gain and small intestine development. Calves fed HQC had higher feed conversion ratios (FCR; total body weight gain/total dry matter intake) compared with LQC calves, and L calves had higher FCR compared with E calves. In conclusion, in comparison to feeding LQC, feeding HQC reduced the scouring duration, enhanced surface area of duodenum and jejunum, and improved FCR during the first 5 wk of calf age. Postpartum collection time of calves did not affect small intestine development, but L calves had higher FCR and required a lesser volume of electrolytes to treat scours compared with E calves during the first 35 d of life.

Prevalence of failure of passive transfer of immunity in dairy calves in a Mediterranean pasture-based production system of the south-west region of Western Australia.

The objective of this study was to estimate the prevalence of failure of passive transfer of immunity (FPTI) in dairy calves in the south-west region of Western Australia herds. A cross-sectional study was conducted in 26/140 dairy farms and serum samples were collected from 495 healthy 2-7 day-old calves. A radial immunodiffusion (RID) test was used to determine the concentration of serum IgG and calves were classified as having FPTI if the IgG concentration was less than 10 mg/mL. Estimation of FPTI was also assessed using two indirect methods using serum total protein (STP) and a brix refractometer. The estimated prevalence of FPTI was found to be 8.7% (43 calves out of 495) by RID with the concentration of IgG ranging between 0 and 6.2 mg/ml. The STP was found to vary from 46 to 96 mg/mL and using a cut-off point of 55 mg/mL the calf level prevalence was estimated as 7.1% (33 calves). Using the brix refractometer, the prevalence was found to be 13.1% (65 calves) with the refractometer reading ranging 6-14% of IgG. In the present study there was no association between calf-level factors (age, sex and breed) and FPTI. There was a higher correlation of the RID test results and the STP results compared to the RID and brix refractometer results. It is concluded that the prevalence of FPTI in dairy calves in the south-west region of Western Australia is low (8.7%) and the brix refractometer is not a reliable indirect method for determining passive transfer of immunity to calves.

Three novel immunogenic proteins determined through 2-Dimensional electrophoresis and mass spectrometry with immune serum confer protection against challenge with porcine Pasteurella multocida in mouse models.

Pasteurella multocida is an important zoonotic pathogen that causes multiple diseases in both animals and humans. Test of good immunogenic proteins is beneficial for vaccine development and disease control. In the present study, we determined four novel immunogenic proteins of P. multocida by using 2-DE MALDI-TOF MS with immune serum. These four proteins included a trimethylamine-N-oxide reductase TorA, a translation elongation factor Ts, a phosphoglyceromutase PGAM, and a peroxiredoxin PrX. Among these proteins, TorA, Prx, and PGAM were successfully expressed by using E. coli. Western-blotting assays showed that recombinant TorA, Prx, and/or PGAM displayed good reactions with infectious sera of P. multocida serogroups A, B, D and F. Immunization of either rTorA, rPrx, and/or rPGAM induced significantly high levels of antibodies as well as IFN-γ, IL-4 and IL-10 in mice (P < 0.01). Protective efficacy tests revealed that vaccination of either rTorA, rPrx, and/or rPGAM protected 60% ~ 80% of the tested mice against the challenge with P. multocida field isolate. Our results obtained from the present study suggest that these three proteins could be tested as good vaccine candidates against P. multocida infections.

Use of convalescent serum reduces severity of COVID-19 in nonhuman primates.

Passive transfer of convalescent plasma or serum is a time-honored strategy for treating infectious diseases. Human convalescent plasma containing antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is currently being used to treat patients with coronavirus disease 2019 where clinical efficacy trials are ongoing. Here, we assess therapeutic passive transfer in groups of SARS-CoV-2-infected African green monkeys with convalescent sera containing either high or low anti-SARS-CoV-2 neutralizing antibody titers. Differences in viral load and pathology are minimal between monkeys that receive the lower titer convalescent sera and untreated controls. However, lower levels of SARS-CoV-2 in respiratory compartments, reduced severity of virus-associated lung pathology, and reductions in coagulopathy and inflammatory processes are observed in monkeys that receive high titer sera versus untreated controls. Our data indicate that convalescent plasma therapy in humans may be an effective strategy provided that donor sera contain high anti-SARS-CoV-2 neutralizing titers given in early stages of the disease.

Causes of neonatal calf diarrhea and mortality in pasture-based dairy herds in Uruguay: a farm-matched case-control study.

Neonatal calf diarrhea (NCD) and mortality cause significant losses to the dairy industry. The preweaning dairy calf mortality risk in Uruguay is high (15.2%); however, causes for these losses are largely unknown. This study aimed to assess whether various pathogens were associated with NCD and death in Uruguayan dairy calves and whether these infections, diarrhea, or deaths were associated with the failure of transfer of passive immunity (FTPI). Contemporary diarrheic (n = 264,) and non-diarrheic (n = 271) 1- to 30-day-old calves from 27 farms were sampled. Feces were analyzed by antigen-capture ELISA for Cryptosporidium spp., rotavirus, bovine coronavirus, and Escherichia coli F5+, RT-PCR for bovine astrovirus (BoAstV), and bacterial cultures for Salmonella enterica. Blood/serum was analyzed by RT-PCR or antigen-capture ELISA for bovine viral diarrhea virus (BVDV). Serum of ≤ 8-day-old calves (n = 95) was assessed by refractometry to determine the concention of serum total proteins (STP) as an indicator of FTPI. Whether the sampled calves died before weaning was recorded. At least one pathogen was detected in 65.4% of the calves, and this percentage was significantly higher in diarrheic (83.7%) versus non-diarrheic (47.6%) calves. Unlike the other pathogens, Cryptosporidium spp. and rotavirus were associated with NCD. Diarrheic calves, calves infected with any of the pathogens, and calves infected with rotavirus had significantly lower concentrations of STP. Diarrheic calves had higher chances of dying before weaning than non-diarrheic calves. Diarrheic calves infected with S. enterica were at increased risk of mortality. Controlling NCD, salmonellosis, cryptosporidiosis, and rotavirus infections, and improving colostrum management practices would help to reduce calf morbi-mortality in dairy farms in Uruguay.

[Prevention of canine parvovirosis - Part 1: Humoral and cellular immunity]. / Prophylaxe der kaninen Parvovirose.

Canine parvovirosis remains a common and highly infectious disease. Thus, adequate protection is essential for all dogs at any time. In this, humoral immunity plays an essential role. The presence of antibodies in adult dogs suggests immunity against the disease, and nearly all adult dogs possess antibodies (either due to previous vaccination or infection). Meanwhile, worldwide vaccination guidelines recommend measurement of pre-vaccination antibodies instead of regular triennial re-vaccinations in adult dogs. Studies have demonstrated a long lasting duration of immunity against canine parvovirus. Re-vaccination therefore possesses no beneficial effect when dogs already have pre-vaccination antibodies. Thus, when antibodies are present, unnecessary re-vaccinations that potentially cause vaccine-associated adverse events should be avoided. Hemagglutination inhibition and virus neutralization can be performed in specialized laboratories for quantitative antibody titer measurement. Semiquantitative point-of-care (POC) tests for detection of CPV antibodies are available. Since the presence of CPV antibodies in adult dogs that have been vaccinated or previously infected suggests adequate immunity against disease, these POC tests can be a useful tool in practice. They identify dogs that might potentially be unprotected and require re-vaccination during preventive health care appointments. Concerning the POC tests' quality assessment, a high specificity (low number of false positive test results) is considered the most important feature.

Effect of litter birth weight standardization before first suckling on colostrum intake, passive immunization, pre-weaning survival, and growth of the piglets.

Within-litter variation in birth weight is a relevant factor in pig production. This study aimed at comparing pre-weaning mortality, colostrum intake (CI), passive immunization, and growth of piglets from litters of uniform (UN) or heterogeneous (HET) birth weights. The study included 52 multiparous sows (Large White × Landrace) and their litters. Two types of litters were constituted based on birth weight, namely: UN or HET, the control group, using piglets from two to three sows farrowing approximately at the same time. At birth, piglets were weighed, identified, and placed in a box under an IR lamp. At the end of farrowing, piglets were re-weighed and allotted to groups UN or HET (12 per litter) with average weights of 1394 and 1390 g, respectively, and allowed to suckle (time 0). They were re-weighed 24 h later to estimate CI and sows' colostrum yield. At time 0, the average intra-litter CV (%) in weight of experimental litters were 9.3 ±â€¯0.8 (SEM) and 27.8 ±â€¯0.7 in groups UN and HET, respectively (P < 0.001). At 2 days of age, blood samples were taken from the piglets of 11 litters five UN and six HET) and serum Immunoglobulin G (IgG) contents were determined. Mean CI/piglet/litter was similar in both groups, that is, 415 ±â€¯13 in UN and 395 ±â€¯13 g in HET (P = 0.28), but was less variable in UN litters (CV = 22.4 ±â€¯2 vs 36.0 ±â€¯2%, P < 0.001). The IgG levels at 2 days of age were higher in piglets from UN litters (22.5 ±â€¯0.8 vs 18.4 ±â€¯0.7 g/l; P < 0.001) but the CV of IgG levels was not different between litter type (P= 0.46). Mortality up to 21 days of age was lower in UN litters (6.4 vs 11.9%, P = 0.03). The BW at 21 days was not different between litter type (P = 0.25) but it was less variable among piglets from UN litters (CV: 17.1 ±â€¯1.3 vs 25.7 ±â€¯1.3%; P = 0.01). Results reveal that CI is less variable and mortality is lower in piglets from litters of UN birth weight. The results infer that genetic improvement to decrease variation in birth weight within-litter could have a positive effect on homogeneous CI and thus contribute to reducing piglet mortality.

Hot topic: Accuracy of refractometry as an indirect method to measure failed transfer of passive immunity in dairy calves fed colostrum replacer and maternal colostrum.

Serum total protein (STP) refractometry is a widely used indicator of failed transfer of passive immunity (FTPI), defined as serum IgG concentrations of <10 mg/mL or STP levels <5.2 g/dL measured at 24 h of life. However, recent reports have demonstrated that refractometry could be inaccurate at estimating serum IgG concentrations and FTPI when calves are fed colostrum replacer (CR). The objective of this study was to evaluate the accuracy of STP measurements to estimate FTPI in calves fed CR compared with calves fed maternal colostrum. Blood was collected from dairy calves fed maternal colostrum (n = 927) or colostrum-derived CR (n = 1,258) and analyzed for STP and serum IgG. Serum total protein was measured with a digital refractometer, whereas radial immunodiffusion was used to determine IgG concentrations. Calves fed maternal colostrum had a mean STP of 5.80 ± 0.72 (standard deviation) g/dL and a mean IgG concentration of 22.81 ± 10.14 mg/mL, respectively, whereas calves fed CR had a mean STP and IgG concentration of 5.14 ± 0.50 g/dL and 12.78 ± 4.60 mg/mL, respectively. Rates of FTPI for calves fed maternal colostrum or CR were 4.2% and 27.26%, respectively. Calves were considered to have FTPI if their IgG postcolostrum feeding was <10 mg/mL. Logistic and linear regression analyses were performed to determine cutoff points and existent relationships between STP and IgG. Serum total protein and IgG for calves fed maternal colostrum were highly correlated. In contrast, STP and IgG for calves fed CR were lowly correlated. A receiver operator characteristic curve analysis demonstrated that an STP cutoff point that could predict FTPI when calves are fed CR would be 4.9 g/dL (sensitivity = 0.68; specificity = 0.75). This study suggests that current cutoff points used for STP inflates the number of calves estimated to have FTPI when they are fed CR.

Interferon lambda protects cattle against bovine viral diarrhea virus infection.

Interferon lambda (IFN-λ) plays an important role in inducing an antiviral state in mucosal surfaces and has been used as an effective biotherapeutic against several viral diseases. Here we performed a proof of concept study on the activity of a biologically active recombinant bovine IFN-λ (rIFN-λ) produced in eukaryotic cells against Bovine Viral Diarrhea Virus (BVDV) in cattle. We first confirmed the lack of toxicity of different concentrations of rIFN-λ in bovine peripheral blood cells and the safety of its subcutaneous application in calves in doses up to 12 IU/kg. The antiviral activity of the rIFN-λ against BVDV was assessed in calves that were inoculated with 6 IU/kg of rIFN-λ (n = 4) or mock-treated (n = 2) two days before and after challenge with a BVDV type-2 non-cytopathic strain. Mock-treated animals developed respiratory disease, shedded the virus from 4 to 7 days post-infection (dpi) and had viremia between 4 and 14 dpi. Conversely, calves treated with rIFN-λ did not develop clinical symptoms. The virus was not found in nasal secretions or sera. Only one animal had a positive viral RNA detection in serum at 7 dpi. All infected animals treated with rIFN-λ increased systemic type-I IFNs levels at 4 dpi. The antiviral treatment induced an earlier onset of the anti-BVDV neutralizing antibodies. Altogether, these results constitute the proof-of-principle of bovine IFN-λ as an antiviral biotherapeutic to protect cattle against the clinical disease caused by BVDV.

Passive Immunization Delays Disease Outcome in Gilthead Sea Bream Infected With Enteromyxum leei (Myxozoa), Despite the Moderate Changes in IgM and IgT Repertoire.

Passive immunization constitutes an emerging field of interest in aquaculture, particularly with the restrictions for antibiotic use. Enteromyxum leei is a myxozoan intestinal parasite that invades the paracellular space of the intestinal epithelium, producing a slow-progressing disease, leading to anorexia, cachexia and mortalities. We have previously demonstrated that gilthead sea bream (GSB, Sparus aurata) that survive E. leei infection become resistant upon re-exposure, and this resistance is directly related to the presence of high levels of specific IgM in serum. Thus, the current work was aimed to determine if passive immunization could help to prevent enteromyxosis in GSB and to study in detail the nature of these protective antibodies. Serum from a pool of resistant (SUR) or naïve (NAI) animals was intracoelomically injected 24 h prior to the E. leei-effluent challenge and at 9 days post-challenge (dpc). Effluent challenge lasted for 23 days, and then the injected groups were allocated in separate tanks with clean water. A non-lethal parasite diagnosis was performed at 56 dpc. At the final sampling (100 dpc), blood, serum and tissues were collected for histology, molecular diagnosis and the detection of circulating antibodies. In parallel, we performed an immunoglobulin repertoire analysis of the fish generating SUR and NAI sera. The results showed that, fish injected with parasite-specific antibodies (spAbs) became infected with the parasite, but showed lower disease signs and intensity of infection than the other groups, indicating a later establishment of the parasite. Repertoire analysis revealed that E. leei induced a polyclonal expansion of diverse IgM and IgT subsets that could be in part an evasion strategy of the parasite. Nonetheless, GSB was able to produce sufficient levels of parasite-spAbs to avoid re-infection of surviving animals and confer certain degree of protection upon passive transfer of antibodies. These results highlight the crucial role of spAb responses against E. leei and set the basis for the development of effective treatment or prophylactic methods for aquaculture.

Orally administered ovine serum immunoglobulins modulate dental plaque in cats.

The effects of orally administered ovine serum immunoglobulin on dental plaque and associated oral immunity in cats were investigated. The two treatment groups consisted of 1) cats that were fed unsupplemented kibble (control diet) and 2) cats that were fed the same kibble but coated with a freeze-dried ovine serum immunoglobulin preparation (ovine Ig) (test diet). The adult cats were randomly allocated to one of the two diets (n = 15) and received their respective kibble for a 28-day experimental period. When compared to the ovine Ig-supplemented kibble, cats consuming the unsupplemented kibble had significantly (p < 0.05) higher dental plaque scores. Cat IgA and IgG concentrations in the saliva and serum were significantly (p < 0.05) higher for cats fed the unsupplemented kibble when compared to cats receiving the ovine Ig supplement. Similarly, myeloperoxidase activity in the saliva was significantly (p < 0.05) higher for cats fed the unsupplemented kibble when compared to cats receiving the Ig-supplement. Orally administered ovine serum Ig positively influenced oral health and oral immunity in cats as evidenced by preventing an increase of dental plaque formation, salivary and serum IgA and IgG concentrations and salivary myeloperoxidase activity.

Passive immunity and colostrum management practices on Ontario dairy farms and auction facilities: A cross-sectional study.

Failed transfer of passive immunity (FTPI) in dairy calves has substantial health consequences, but there have been no recently published estimates of the prevalence of FTPI on Ontario dairy farms. The major objectives of this cross-sectional study were to determine the level of FTPI in dairy calves across the province of Ontario and to determine colostrum management practices used. A convenience sample of 109 dairy farms in Ontario were visited from June to August 2019, along with 4 auction facilities from January to February 2019. At the single visit to each dairy farm, an in-person questionnaire was administered, and all calves between 24 h and 9 d of age had a blood sample collected to determine the levels of serum total protein (STP). At the auction facility, a blood sample was collected on all calves that arrived on the day of the visit. The dairy farms were distributed throughout Ontario, and the farms milked on average 151 dairy cows. Of the 444 calves sampled on Ontario dairy farms, 46% were male, 54% were female, and the mean weight and age at sampling were 46.3 kg and 4.4 d, respectively. The mean STP of calves sampled on the dairy farm was 5.69 g/dL (standard deviation = 0.78), and 107 calves (24%) had FTPI. The likelihood of FTPI was not associated with sex (female vs. male, risk ratio = 0.89, 95% confidence interval = 0.64-1.24), age (per day, risk ratio = 1.02, 95% confidence interval = 0.94-1.11), or weight (per kg, risk ratio = 0.98, 95% confidence interval = 0.96-1.01). In contrast, at the auction facilities, 386 male dairy calves were sampled and had a mean STP of 5.79 g/dL (standard deviation = 0.83). Using a cut point of ≥5.2 g/dL, 91 calves (24%) had FTPI. From the in-person questionnaire administered on the dairy farms, it was reported that the median time to first feeding of colostrum was 2.5 h (range = 0-12 h). The farms reported providing a mean of 3.3, 2.9, and 3.4 L of colostrum from 0 to 6 h after birth, 6 to 12 h after birth, and 12 to 24 h after birth, respectively. Ninety-one farms (83%) fed colostrum from the dam of the calf as their predominant source of colostrum. The most common method used to deliver the first feeding of colostrum was a nipple bottle (89 farms, 82%). Twenty-seven farms (25%) reported managing colostrum differently for male calves, which included a different colostrum source, use of poorer quality colostrum, a smaller quantity of colostrum, a longer time from birth to feeding, and generally having a lower focus on colostrum management for male calves. The prevalence of FTPI on Ontario dairy farms appears to have decreased since previous estimates, and substantial room for improvement remains. Although no overall differences were found in FTPI between male and female calves, differential reported colostrum management by sex indicates this may be a risk for male calves on a proportion of Ontario dairy farms.