Response of early-weaned pigs to an enterotoxigenic Escherichia coli (K88) challenge when fed diets containing spray-dried porcine plasma or pea protein isolate plus egg yolk antibody

Adaptation of an in-vitro digestion model with different zinc-supplementation strategies on nutrient degradation of piglets

In-vitro studies are widely used in nutrition research. Two major challenges using in-vitro models in animal nutrition research are the individual adaptation of in-vitro digestion models to varying physiological conditions and small digesta output limiting sample material for further analysis. Since several years, the use of zinc in animal production has been legally reduced to control zinc emissions. Earlier, zinc doses around 3000 mg/kg diet were used to prevent post-weaning diarrhea and promote growth in weaning piglets. The first aim of this study was to adapt an in-vitro digestion system for piglets with increased sample output. The second aim was to study the effect of a titanium-bound zinc source at legal dietary inclusion levels on nutrient degradation in an in-vitro digestion model. The experiment was conducted in a 2x2 factorial design incubating 2 different feeds (1. control feed: a commercial piglet diet containing 75 mg zinc per kg diet and 2. treatment feed: control feed with 50 mg of a titanium-bound zinc oxide) in in-situ digestion bags in the Ankom Daisy® incubator with or without digestive enzymes (pepsin, pancreatic enzymes and bile salts). Residuals of incubated feed were analyzed for crude ash, crude protein and starch. The addition of pepsin, pancreatic enzymes and bile salts significantly increased organic matter, crude protein and starch degradation from the digested feed, therefore making the distinction of nutrient disappearance due to enzyme activity versus due to dissolution possible. In conclusion we established an in-vitro digestion model to evaluate the effect of addition of a new zinc source on the enzymatic digestion in piglets. However, addition of the new zinc source did not significantly improve nutrient degradation in the in-vitro digestion model.

Chemical Composition and Functional Properties of Spray-Dried Animal Plasma and Its Contributions to Livestock and Pet Health: A Review

Spray-dried animal plasma (SDAP) is a functional ingredient derived from healthy animal blood, used as a nutritional additive in livestock and pet nutrition. SDAP is rich in macronutrients, micronutrients, and bioactive compounds such as immunoglobulins, albumin, growth factors, peptides, transferrin, and enzymes. This review focuses on the chemical composition of SDAP from porcine, bovine, and poultry sources, including protein quality and mineral profile. SDAP enhances performance and health in monogastric farm animals, aquaculture, and pets. It promotes growth rates and feed intake due to its high digestibility and superior amino acid profile compared to other protein sources. In pigs, SDAP's positive effects stem from tissue-specific actions in the gastrointestinal tract, impacting digestion, immunity, and barrier function. For poultry, SDAP shows promise as a substitute for antibiotic growth promoters, particularly in chick starter diets. SDAP contains functional proteins that regulate immune response, enhance intestinal health, and aid in stress conditions. It is also used as a binder in pet food, providing high protein content and other desirable properties. SDAP meets the dietary requirements of carnivorous pets, appealing to owners seeking animal-derived protein sources. Additionally, SDAP may help prevent cognitive impairment in senior dogs and cats.

A dietary spray-dried plasma feeding programme improves growth performance and reduces faecal bacterial shedding of nursery pigs challenged with enterotoxigenic Escherichia coli K88

This study aimed to assess the effects of different spray-dried plasma (SDP) feeding programmes to pigs on performance, intestinal histomorphology and faecal bacterial shedding after an Escherichia coli K88 challenge. A total of 96 piglets (5.77 ± 0.01 kg) were weaned at 21 days of age (Day 0) and challenged with 3 ml of 1 × 10¹⁰  CFU of E. coli K88 in total 3.0 × 10¹⁰  CFU/animal on Days 0, 2 and 4. Pigs were fed nursery diets containing 0.0%, 3.0%, 6.0% or 9.0% SDP from weaning to 35 days of age; 0.0%, 1.5%, 3.0% or 4.5% SDP from 36 to 49 days; and the same control diet (without SDP), for the last 10 days of the experiment (50-59 days of age). Performance was measured from 35 to 59 days of age and faecal bacterial shedding and intestinal histomorphometry were evaluated at Days 28 and 49 of age respectively. From 21 to 35 days of age, there was a linear effect for body weight (BW) and average daily gain (ADG), a trend of linear effect for average daily feed intake (ADFI) and a quadratic effect for feed:gain ratio (FG). From 21 to 49 days, the 9.0:4.5% and 6.0:3.0% SDP feeding programmes improved BW, ADG and FG when compared to the other treatments. At 59 days of age, BW and ADG were increased by the two highest SDP feeding programmes. The 9.0:4.5% SDP feeding programme increased ADFI from 21 to 59 days of age, with 6.0:3.0% being intermediate and the other two treatments being lowest. The CFU counts of E. coli/g of faeces decreased linearly with increasing addition of SDP. These results indicate that an extended inclusion of increased SDP levels in post-weaning diets can improve growth potential and decrease bacterial shedding induced by E. coli K88.

Effect of Replacing in-Feed Antibiotic Growth Promoters with a Combination of Egg Immunoglobulins and Phytomolecules on the Performance, Serum Immunity, and Intestinal Health of Weaned Pigs Challenged with Escherichia coli K88

Simple Summary

Post-weaning diarrhea (PWD) in pigs caused by Escherichia coli (E. coli) is a global problem which results in substantial economic losses, due to decreased performance and a high incidence of mortality and morbidity. Due to the banning of antibiotic growth promoters (AGPs) by many countries, it would be valuable to find environmentally friendly and non-antibiotic alternatives to AGPs and to evaluate their effectiveness. Both immunoglobulins and phytomolecules are separately reported as benefiting animal growth, but the efficiency of combinations of immunoglobulins and phytomolecules as AGP alternatives is largely unknown. In this study, the results showed that a mixture of immunoglobulin and phytomolecule administration had positive effects on feed efficiency, diarrhea reduction, intestinal morphology, and coliform control. Combinations of immunoglobulins and phytomolecules can be used as a potential alternative to AGPs in weanling piglets.

Abstract

The study was conducted to investigate the effects of replacing antibiotic growth promoters (AGPs) with an egg immunoglobulin (IgY) combined with phytomolecules (PM) on the growth rate, serum immunity, and intestinal health of weaned pigs challenged with Escherichia coli K88 (E. coli K88). A total of 192 piglets were weaned at 28 days old with an average weight of 7.29 (± 0.04) kg. They were randomly divided into four treatments containing eight replicates with six piglets per replicate. The treatment groups were NC and PC fed a basal diet, AGP fed a basal diet supplemented with 75 mg/kg chlortetracycline, 50 mg/kg oxytetracycline calcium, and 40 mg/kg zinc bacitracin, IPM fed a basal diet supplemented with IgY at dose of 2.5 g/kg and 1.0 g/kg and PM at dose of 300 mg/kg and 150 mg/kg during days 1 to 17 and 18 to 42, respectively. On days 7 to 9 of the experiment, piglets in the PC, AGP, and IPM groups were orally challenged with 20 mL E. coli K88 (10⁹ CFU/mL), while piglets in the NC group were challenged with 20 mL medium without E. coli K88. The E. coli K88 challenge model was successful as the incidence of post-weaning diarrhea (PWD) of piglets challenged with E. coli K88 was significantly higher than that of those unchallenged piglets during the challenge time (days 7 to 9) and days 1 to 7 of post-challenge (p < 0.05). A diet with combinations of IgY and PM and AGPs significantly decreased the incidence of PWD during the challenge time and days 1 to 7 of post-challenge (p < 0.05) compared to the PC group and significantly improved the ratio of feed to weight gain (F:G) during days 1 to 17 of the experiment compared to the NC and PC groups (p < 0.05). In comparison with the PC group, piglets in the IPM group had significantly higher serum levels of IgA, IgG, and IgM (p < 0.05), but lower serum IL-1β on day 17 of experiement (p < 0.05). Besides, diet supplementation with AGP significantly decreased serum IL-1β, IL-6, and TNF-α on days 17 and 42 (p < 0.05) with comparison to the PC group. Piglets in the IPM group showed a significantly lower level of fecal coliforms (p < 0.05), but a higher villus height of jejunum and ileum and higher ratio of villus height to crypt depth of duodenum and jejunum (p < 0.05) than those piglets in the PC group. In summary, diet supplementation with a mixture of IgY and PM decreased the incidence of PWD and coliforms, increased feed conversion ratio, and improved intestinal histology and immune function.

Towards Zero Zinc Oxide: Feeding Strategies to Manage Post-Weaning Diarrhea in Piglets

Simple Summary

Zinc oxide (ZnO) supplementation at pharmacological doses in post-weaning piglets is a consolidated practice that allows efficient control of post-weaning diarrhea (PWD), a condition exacerbated by Escherichia coli F4 (K88) infections. Far from being completely elucidated, the multifactorial ZnO mechanism of action is in all likelihood exerted at the gastrointestinal level. However, increasing environmental concerns are arising from prolonged ZnO use. This article reviews the utilization of ZnO in piglets, the biological rationale behind its powerful activity, and the emerging threats that are leading towards a significant reduction in its use. Finally, a wide analysis of the strengths and weaknesses of innovative alternative strategies to manage PWD at the nutritional level is given.

Abstract

Zinc oxide (ZnO) at pharmacological doses is extensively employed in the pig industry as an effective tool to manage post-weaning diarrhea (PWD), a condition that causes huge economic losses because of its impact on the most pivotal phase of a piglet’s production cycle. In a multifactorial way, ZnO exerts a variety of positive effects along the entire gastrointestinal tract by targeting intestinal architecture, digestive secretions, antioxidant systems, and immune cells. ZnO also has a moderate antibacterial effect against Escherichia coli F4 (K88), the main causative agent of PWD. However, the environmental impact of ZnO and new emerging threats are posing serious questions to the sustainability of its extensive utilization. To work towards a future free from pharmacological ZnO, novel nutritional approaches are necessary, and many strategies have been investigated. This review article provides a comprehensive framework for ZnO utilization and its broad mode of action. Moreover, all the risks related to pharmacological ZnO levels are presented; we focus on European institutions’ decisions subsequently. The identification of a novel, complete solution against PWD should be accompanied by the adoption of holistic strategies, thereby combining good management practices to feeding approaches capable of mitigating Escherichia coli F4 (K88) infections and/or lowering ZnO utilization. Promising results can be obtained by adjusting diet composition or employing organic acids, natural identical compounds, polyphenol-rich extracts, prebiotics, and probiotics.

The impact of porcine spray-dried plasma protein and dried egg protein harvested from hyper-immunized hens, provided in the presence or absence of subtherapeutic levels of antibiotics in the feed, on growth and indicators of intestinal function and physiology of nursery pigs

The objective of this experiment was to compare the effects of spray-dried plasma protein (SDPP) and dried egg protein (DEP), without (AB-) or with (AB+) in-feed antibiotics, on growth performance and markers of intestinal health in nursery pigs raised in commercial conditions. This 42-d experiment utilized 1,230 pigs (4.93 ± 0.04 kg body weight; approximately 15-18 d of age). Pigs were randomly assigned to one of six dietary treatments that were arranged as a 2 × 3 factorial of in-feed antibiotics (AB- vs. AB+) and a specialty protein additive (none [CON], porcine SDPP, or DEP). Diets were fed in four phases with phases 3 and 4 as a common diet across all treatments. Specialty protein additives were fed in phases 1 (0-13 d; 3% SDPP, and 0.20% DEP) and 2 (13-26 d; 2% SDPP, and 0.10% DEP). Antibiotics were fed in phases 1-3 (662 mg chlortetracycline [CTC]/kg, 28 mg carbadox/kg, and 441 mg CTC/kg, respectively). Ileal tissue and blood samples were collected from 48 pigs (8 per treatment) on d 20. Data were analyzed using PROC MIXED of SAS (9.4) with pen as the experimental unit; protein additives, antibiotics, and their interaction were fixed effects and block was a random effect. The pigs experienced naturally occurring health challenges in weeks 2 and 4. In the AB- diets, SDPP and DEP increased average daily gain (ADG; P = 0.036) and average daily feed intake (ADFI; P = 0.040) compared to CON; in the AB+ diets, neither SDPP nor DEP increased ADG or ADFI compared to CON but SDPP did increase these parameters over DEP. The SDPP and DEP diets decreased the number of individual medical treatments compared to CON (P = 0.001). The AB+ increased ileal mucosal interleukin (IL)-1 receptor antagonist (P = 0.017). Feeding DEP reduced the concentration of mucosal IL-1β compared to CON, but not SDPP (P = 0.022). There was a trend for SDPP and DEP to increase villus height:crypt depth compared to CON (P = 0.066). Neither antibiotics or protein additive affected serum malondialdehyde concentration or ileal mRNA abundance of claudin-3 or 4, occludin, or zonula occludens-1 (P > 0.10). In conclusion, SDPP and DEP improved growth performance of weaned pigs in the absence of antibiotics but neither improved growth compared to CON when feeding standard antibiotic levels. The specialty proteins had a positive effect on health; specialty proteins and antibiotics were able to modulate some markers of intestinal inflammation and morphology.

Spray-dried porcine plasma improves feed intake of weaned piglets subjected to heat stress

The objective of this study was to evaluate the effects of spray-dried porcine plasma (SDPP) on performance, measurement of thyroid hormones triiodothyronine (T3) and thyroxine (T4), body temperature and relative organ weights of weaned piglets exposed to a heat stress or a thermoneutral environment. One hundred and forty-four piglets with initial BW of 5.82 ± 0.33 kg (28 d old) were used. The experimental design was a 4 x 2 factorial arrangement, four plasma levels (0.0, 2.5, 5.0 and 7.5%) and two environments (34º [heat stress (HS)] and 24°C [thermoneutral (TN)]). SDPP was fed from weaning (28 d of age) to the end of the trial (piglets were weighed at the beginning, 7, 21 and 35 days of trial). Rectal, neck, shoulder and leg temperatures were measured every seven days. At 21 days of trial, one piglet per pen was slaughtered to determine the weight of the carcass and organs. Blood samples were collected at 18 and 35 days of trial to determine levels T3 and T4. The rectal, neck, shoulder and leg temperatures were increased (p < 0.05) 0.4, 1.5, 1.0 and 1.3ºC, respectively, and relative weight of the lungs (p < 0.05) and total T3 (p < 0.05) were decreased 0.001 kg/kg and 0.19 ng/dl, respectively, for pigs in the HS environment. The estimated inclusion of 5.1% of SDPP had the greatest (p < 0.05) weight gain during the first week, and throughout the nursery phase, the 5% of inclusion had a tendency of improvement (p = 0.075), regardless of ambient temperature. For the entire period, pigs reared in the HS environment had the greatest (p < 0.05) estimated feed intake by the quadratic regression with the inclusion of 4.3% of SDPP.

Evaluation of standardized ileal digestible lysine requirement for 8-20 kg pigs fed low crude protein diets

Two experiments were conducted to determine the standardized ileal digestible lysine (SID Lys) requirement for weaned pigs fed with low crude protein (CP) diet. In Experiment 1, 144 pigs were fed a normal CP (20%) diet with 12.3 g/kg SID Lys and five low CP (18.5%) diets providing SID Lys levels of 9.8, 11.1, 12.3, 13.5, and 14.8 g/kg, respectively, for 28 days. Reducing dietary CP from 20% to 18.5% enhanced (p < 0.05) the growth performance. The average daily gain (ADG) and gain to feed ratio (G:F) increased (linear and quadratic; p < 0.05), serum urea nitrogen (SUN) decreased (linear and quadratic; p < 0.05) as SID Lys increased. The SID Lys levels required to maximize ADG and optimize G:F were 12.8 and 13.1 g/kg using a curvilinear plateau model, and to minimize SUN was 13.4 g/kg using a two-slope broken-line model, which averaged 13.1 g/kg SID Lys. In Experiment 2, 18 pigs were used in a 12-day N balance trial and received the same diets of Experiment 1. Total N excretion was decreased when dietary CP reduced and further decreased when SID Lys increased. Collectively, 1.5% dietary CP reduction improved the growth performance and decreased the N excretion; the optimal SID Lys requirement was at 13.1 g/kg of 8-20 kg pigs fed with 18.5% CP diet.

Spray-dried plasma attenuates inflammation and lethargic behaviors of pregnant mice caused by lipopolysaccharide

This study evaluated whether dietary spray-dried plasma (SDP) can ameliorate inflammation, lethargic behaviors, and impairment of reproduction caused by lipopolysaccharide (LPS) challenge during late pregnancy. Two experiments were conducted with 125 mated female mice (C57BL/6 strain) in each experiment. All mice were shipped from a vendor on the gestation day (GD) 1 and arrived at the laboratory on GD 3. Mice were randomly assigned to dietary treatments with or without 8% SDP in the diet. On GD 17, mice determined pregnant by BW and abdomen shape were randomly assigned to intraperitoneal injections with or without 2 μg LPS. In experiment 1, 17 mice (26.7 ± 1.7 g BW) were identified pregnant and euthanized 6 h after the LPS challenge to measure inflammatory responses in uterus and placenta. In experiment 2, 44 mice (26.0 ± 1.6 g BW) were identified pregnant and euthanized 24 h after the LPS challenge to assess behavior and late-term pregnancy loss. Growth performance and reproductive responses, such as loss of pregnancy, percentage of fetal death, and etc., were measured in all pregnant mice. The LPS challenge increased (P < 0.05) uterine and placental tumor necrosis factor-α and interferon-γ, late-term pregnancy loss, and lethargy score, and decreased (P < 0.05) uterine transforming growth factor-β1, moving time and number of rearing, and growth and feed intake. The SDP decreased (P < 0.05) concentrations of both pro-inflammatory and anti-inflammatory cytokines in one or both tissues, and the lethargy score, and increased (P < 0.05) moving time and number of rearing, growth of pregnant mice, and fetal weight. However, the SDP did not affect late-term pregnancy loss caused by the LPS challenge. Consequently, dietary SDP attenuated acute inflammation and lethargic behaviors of pregnant mice caused by the LPS challenge, but did not affect late-term pregnancy loss after the acute inflammation.

Dietary spray-dried plasma improves intestinal morphology of mated female mice under stress condition

Background

Stress causes inflammation that impairs intestinal barrier function. Dietary spray-dried plasma (SDP) has recognized anti-inflammatory effects and improvement of gut barrier function. Therefore, the purpose of this study was to investigate the effects of dietary SDP on intestinal morphology of mated female mice under stress condition.

Results

Villus height, width, and area of small intestines were low on gestation day (GD) 3 or 4 under stress conditions, and higher later (Time, P < 0.05). Crypt depth of colon was low on GD 4 and higher later (Time, P < 0.05). Meanwhile, the SDP treatments improved (P < 0.05) intestinal morphology, indicated by increased villus height, villus width, villus area, and ratio between villus height and crypt depth of small intestines and crypt depth of colon, and by decreased crypt depth of small intestines, compared with the control diet. The SDP treatments also increased (P < 0.05) the number of goblet cells in intestines compared with the control diet. There were no differences between different levels of SDP.

Conclusion

Dietary SDP improves intestinal morphology of mated female mice under stress condition.

Optimal sulfur amino acid to lysine ratio for post weaning piglets reared under clean or unclean sanitary conditions

Two 14-day experiments, each with 90 (Duroc × [Yorkshire × Landrace]; 7.3 ± 0.6 kg) piglets, were conducted to determine the optimum sulfur amino acid (SAA) to lysine (Lys) ratio (SAA:Lys) for piglets when reared under clean or unclean sanitary conditions using performance and non-performance response criteria. Piglets were randomly assigned to the following dietary treatments. The basal diet contained 1.18% standardized ileal digestible (SID) Lys, and the SAA:Lys was 52%. In diets 2 to 5, the basal diet was supplemented with 4 graded levels of dl-Met to make SAA:Lys of 56%, 60%, 64% and 68%. In Exp. 1, piglets were housed in disinfected clean room. In Exp. 2, piglets were housed in a room previously occupied by other pigs and was not disinfected. On the last day, blood was collected to measure plasma urea nitrogen (PUN) and one pig per pen was euthanized to collect jejunal tissue to measure villus height (VH), crypt depth (CD), and VH:CD. In Exp. 1, increasing SAA:Lys linearly and quadratically increased VH and VH:CD (P < 0.05). In Exp. 2, increasing SAA:Lys linearly increased (P < 0.05) VH and VH:CD and linearly and quadratically decreased PUN (P < 0.05). Estimated PUN and VH-based optimum SAA:Lys requirements for clean and unclean sanitary condition were 60%, 63% and 66%, respectively.

Growth performance, gastrointestinal microbial activity, and immunological response of piglets receiving microencapsulatedEnterococcus faecalisCG1.0007 and enzyme complex after an oral challenge withEscherichia coli(K88)

The aim of this study was to determine effects of dietary microencapsulated Enterococcus faecalis CG1.0007 probiotic and multienzyme complex (MC) in Enterotoxigenic Escherichia coli K88 (ETEC) challenged piglets. Thirty-six, 21-d-old weanling pigs were randomly allotted to four dietary treatments: a wheat–barley based negative control (NC), NC + MC, NC + probiotic, and NC + MC + probiotic. After 7-d acclimatization to treatments, pigs were weighed, blood was sampled, and then the pigs were orally challenged with an ETEC inoculum. After the challenge, blood was sampled at different time points; performance measures and fecal consistency scores were recorded; and on day 14, all pigs were killed to obtain intestinal tissue samples. During prechallenge, pigs receiving enzyme, probiotic, and a combination of both showed a significant improvement in daily gain (P = 0.03) and feed efficiency (P = 0.04) compared with control. During the postchallenge period, a greater (P = 0.05) ileal villus height was observed for diets supplemented with probiotic alone. Overall, pigs fed diets with probiotic alone also showed less incidence of diarrhea (P = 0.04) compared with control. In summary, the results indicate that dietary supplementation with microencapsulated Enterococcus faecalis CG1.0007 in weaned piglets challenged with ETEC was effective in controlling diarrhea.

Spray dried plasma as an alternative to antibiotics in piglet feeds, mode of action and biosafety

The use of growth promoting and therapeutic antibiotics in piglet feed has been a concerning subject over the last few decades because of the risk of generating antimicrobial resistance that could be transferred to humans. As a result, many products have been proposed as potential alternatives to the use of antibiotics, and among these, spray dried plasma is considered one of the most promising. However, there have been concerns about its biosafety, particularly during periods of emergence or re-emergence of swine diseases in different regions of the world, such as the recent porcine epidemic diarrhea virus outbreak in North America. The objectives of this paper are to review recent publications about the use of spray dried plasma as an alternative to antibiotics in weaned pig diets, the possible mechanisms of action of spray dried plasma, and the existing evidence related to the biosafety of spray dried animal plasma. Particular attention is given to studies in which spray dried plasma has been directly compared to antibiotics or other alternative antimicrobial products. Several studies on the possible modes of action for spray dried plasma, such as preservation of gut barrier function or modulation of the immune response, are also reviewed. Finally, the paper focuses on the review of the existing studies on the risks of disease transmission with the use of spray dried plasma from porcine origin. Overall, spray dried plasma is a promising alternative to in-feed antimicrobials for piglets, particularly during the early stages of the post-weaning phase. Additionally, there is enough evidence to support that commercial spray dried porcine plasma is a safe product for pigs.

Gut Health of Pigs: Challenge Models and Response Criteria with a Critical Analysis of the Effectiveness of Selected Feed Additives - A Review

The gut is the largest organ that helps with the immune function. Gut health, especially in young pigs has a significant benefit to health and performance. In an attempt to maintain and enhance intestinal health in pigs and improve productivity in the absence of in-feed antibiotics, researchers have evaluated a wide range of feed additives. Some of these additives such as zinc oxide, copper sulphate, egg yolk antibodies, mannan-oligosaccharides and spray dried porcine plasma and their effectiveness are discussed in this review. One approach to evaluate the effectiveness of these additives in vivo is to use an appropriate disease challenge model. Over the years, researchers have used a number of challenge models which include the use of specific strains of enterotoxigenic Escherichia coli, bacteria lipopolysaccharide challenge, oral challenge with Salmonella enteric serotype Typhimurium, sanitation challenge, and Lawsonia intercellularis challenge. These challenge models together with the criteria used to evaluate the responses of the animals to them are also discussed in this review.

Passive immunisation, an old idea revisited: Basic principles and application to modern animal production systems

Immunisation by administration of antibodies (immunoglobulins) has been known for more than one hundred years as a very efficient means of obtaining immediate, short-lived protection against infection and/or against the disease-causing effects of toxins from microbial pathogens and from other sources. Thus, due to its rapid action, passive immunisation is often used to treat disease caused by infection and/or toxin exposure. However immunoglobulins may also be administered prior to exposure to infection and/or toxin, although they will not provide long-lasting protection as is seen with active immunisation (vaccination) in which an immunological memory is established by controlled exposure of the host to the pathogen in question. With multi-factorial infectious diseases in production animals, especially those that have proven hard to control by vaccination, the potential of passive immunisation remains big. This review highlights a number of examples on the use of passive immunisation for the control of infectious disease in the modern production of a range of animals, including pigs, cattle, sheep, goat, poultry and fish. Special emphasis is given on the enablement of passive immunisation strategies in these production systems through low cost and ease of use as well as on the sources, composition and purity of immunoglobulin preparations used and their benefits as compared to current measures, including vaccination (also comprising maternal vaccination), antibiotics and feed additives such as spray-dried plasma. It is concluded that provided highly efficient, relatively low-price immunoglobulin products are available, passive immunisation has a clear role in the modern animal production sector as a means of controlling infectious diseases, importantly with a very low risk of causing development of bacterial resistance, thus constituting a real and widely applicable alternative to antibiotics.

Nutritional Impact of Dietary Plasma Proteins in Animals Undergoing Experimental Challenge and Implications for Patients with Inflammatory Bowel Disorders: A Meta-analysis

Studies administering plasma protein isolates (PPIs) to experimentally challenged animals have reported improvements in growth, food intake, and overall condition when compared with animals fed control diets, due in part to improvements in gut barrier function, normalization of cytokine signals, and support of enteric immune function. These and early clinical studies suggest that nutritional therapy with PPIs may similarly assist in restoring homeostasis to gut barrier function in humans experiencing mild or more acute enteropathic symptomatology such as irritable bowel syndrome and inflammatory bowel disease. This meta-analysis evaluated the ability of PPIs to promote weight gain and food intake in weanling animals, primarily piglets, after oral challenge with various enteric pathogens or bacterial toxins. MEDLINE, EMBASE, and PubMed were searched from 1980 through August 2012 for specified terms and keywords. Twenty-nine articles retrieved through this process were evaluated; 11 studies including 13 experiments were selected for inclusion in the analysis. The meta-analysis included descriptive analyses and methods for combining P values for the primary endpoint, average daily growth (ADG) at week 1, and secondary endpoints including ADG, average daily feed intake (ADFI), and gain to feed ratio (G:F) at weeks 1 and 2 and at the end of study. Primary and secondary endpoint analyses of growth (ADG, ADFI, and G:F) were significant (P < 0.01). The proinflammatory cytokines interleukin (IL) 1β, IL-6, and tumor necrosis factor α were significantly lower in animals fed dietary PPIs. Additional research in patients experiencing symptoms of enteropathy will further characterize the benefits of PPIs in clinical populations.

Chicken egg yolk antibodies (IgY) as non-antibiotic production enhancers for use in swine production: a review

In recent years, the use of in-feed antibiotics for growth and disease prevention in livestock production has been under severe scrutiny. The use and misuse of in-feed antibiotics has led to problems with drug residues in animal products and increased bacterial resistance. Chicken egg yolk antibodies (IgY) have attracted considerable attention as an alternative to antibiotics to maintain swine health and performance. Oral administration of IgY possesses many advantages over mammalian IgG such as cost-effectiveness, convenience and high yield. This review presents an overview of the potential to use IgY immunotherapy for the prevention and treatment of swine diarrhea diseases and speculates on the future of IgY technology. Included are a review of the potential applications of IgY in the control of enteric infections of either bacterial or viral origin such as enterotoxigenic Escherichia coli, Salmonella spp., rotavirus, porcine transmissible gastroenteritis virus, and porcine epidemic diarrhea virus. Some potential obstacles to the adoption of IgY technology are also discussed.

Chicken egg yolk antibodies (IgY) as non-antibiotic production enhancers for use in swine production: a review

In recent years, the use of in-feed antibiotics for growth and disease prevention in livestock production has been under severe scrutiny. The use and misuse of in-feed antibiotics has led to problems with drug residues in animal products and increased bacterial resistance. Chicken egg yolk antibodies (IgY) have attracted considerable attention as an alternative to antibiotics to maintain swine health and performance. Oral administration of IgY possesses many advantages over mammalian IgG such as cost-effectiveness, convenience and high yield. This review presents an overview of the potential to use IgY immunotherapy for the prevention and treatment of swine diarrhea diseases and speculates on the future of IgY technology. Included are a review of the potential applications of IgY in the control of enteric infections of either bacterial or viral origin such as enterotoxigenic Escherichia coli, Salmonella spp., rotavirus, porcine transmissible gastroenteritis virus, and porcine epidemic diarrhea virus. Some potential obstacles to the adoption of IgY technology are also discussed.

Porcine epidemic diarrhea virus RNA present in commercial spray-dried porcine plasma is not infectious to naïve pigs

Porcine epidemic diarrhea virus emerged in North America in April 2013 and has since been identified in 30 U.S. States, Canada and Mexico. The rapid spread of PEDV has raised concerns about the role of feed and particularly pork-by-product components such as spray-dried porcine plasma (SDPP) in PEDV transmission. The aim of this study was to determine the infectivity of PEDV RNA present in commercial SDPP. Specifically, 40 3-week-old PEDV naïve pigs were randomly assigned to one of five treatment groups. At day post inoculation (dpi) 0, NEG-CONTROL pigs were sham-inoculated, PEDV-CONTROL pigs received cell culture propagated PEDV, and SDPP-CONTROL pigs were switched to a diet with 5% SDPP containing 5.1±0.1 log10 PEDV RNA copies/g. To evaluate a potential positive effect of anti-PEDV antibodies in SDPP on PEDV challenge, four days prior to PEDV challenge the pigs in the SDPP-PEDV group were switched to and remained on a 5% SDPP diet through dpi 28. Another group, EGG-PEDV, was orally administered a commercial egg-derived liquid PEDV globulin product from dpi -4 through 6. All PEDV-CONTROL pigs began shedding PEDV in feces by dpi 3 and seroconverted between dpi 7 and 14, whereas pigs in NEG-CONTROL and SDPP-CONTROL groups remained PEDV RNA negative and did not seroconvert to PEDV for the study duration. This indicates no evidence of infectivity of the PEDV RNA in the SDPP lot utilized. Furthermore, under the study conditions SDPP or egg-derived liquid PEDV globulin addition did not significantly alter PEDV-shedding or overall disease course after experimental challenge.

Effect of chicken egg yolk antibodies (IgY) against diarrhea in domesticated animals: a systematic review and meta-analysis

BACKGROUND

IgY antibodies are serum immunoglobulin in birds, reptiles and amphibians, and are transferred from serum to egg yolk to confer passive immunity to their embryos and offspring. Currently, the oral passive immunization using chicken IgY has been focused as an alternative to antibiotics for the treatment and control of diarrhea in animals and humans. This systematic review was focused to determine the effect of IgY in controlling and preventing diarrhea in domesticated animals including Piglets, Mice, Poultry and Calves.

METHODS AND RESULTS

Previous research reports focused on treatment effect of Chicken IgY against diarrhea were retrieved from different electronic data bases (MEDLINE, EMBASE, SPRINGER-LINK, WILEY, AGRICOLA, MEDWELL Journals, Scientific Publish, Chinese articles from Core periodicals in 2012). A total of 61 studies in 4 different animal classes met the inclusion criteria. Data on study characteristics and outcome measures were extracted. The pooled relative risk (RR) of 49 studies of different animals [Piglets--22; Mice--14; Poultry--7 and Calves--6] in meta-analyses revealed that, IgY significantly reduced the risk of diarrhea in treatment group when compare to the placebo. However, the 95% confidence intervals of the majority of studies in animal class piglets and calves embrace RR of one. The same results were obtained in sub group analyses (treatment regiment--prophylactic or therapeutic; pathogen type--bacterial or viral). Perhaps, this inconsistency in the effect of IgY at the individual study level and overall effect measures could be influenced by the methodological heterogeneity.

CONCLUSION

The present systematic review (SR) and meta-analysis demonstrated the beneficial effect of IgY. This supports the opinion that IgY is useful for prophylaxis and treatment. However, more intensive studies using the gold standard animal experiments with the focus to use IgY alone or in combination with other alternative strategies are indispensable.

Effect of chicken egg yolk antibodies (IgY) against diarrhea in domesticated animals: a systematic review and meta-analysis

BACKGROUND

IgY antibodies are serum immunoglobulin in birds, reptiles and amphibians, and are transferred from serum to egg yolk to confer passive immunity to their embryos and offspring. Currently, the oral passive immunization using chicken IgY has been focused as an alternative to antibiotics for the treatment and control of diarrhea in animals and humans. This systematic review was focused to determine the effect of IgY in controlling and preventing diarrhea in domesticated animals including Piglets, Mice, Poultry and Calves.

METHODS AND RESULTS

Previous research reports focused on treatment effect of Chicken IgY against diarrhea were retrieved from different electronic data bases (MEDLINE, EMBASE, SPRINGER-LINK, WILEY, AGRICOLA, MEDWELL Journals, Scientific Publish, Chinese articles from Core periodicals in 2012). A total of 61 studies in 4 different animal classes met the inclusion criteria. Data on study characteristics and outcome measures were extracted. The pooled relative risk (RR) of 49 studies of different animals [Piglets--22; Mice--14; Poultry--7 and Calves--6] in meta-analyses revealed that, IgY significantly reduced the risk of diarrhea in treatment group when compare to the placebo. However, the 95% confidence intervals of the majority of studies in animal class piglets and calves embrace RR of one. The same results were obtained in sub group analyses (treatment regiment--prophylactic or therapeutic; pathogen type--bacterial or viral). Perhaps, this inconsistency in the effect of IgY at the individual study level and overall effect measures could be influenced by the methodological heterogeneity.

CONCLUSION

The present systematic review (SR) and meta-analysis demonstrated the beneficial effect of IgY. This supports the opinion that IgY is useful for prophylaxis and treatment. However, more intensive studies using the gold standard animal experiments with the focus to use IgY alone or in combination with other alternative strategies are indispensable.

Escherichia coli challenge and one type of smectite alter intestinal barrier of pigs

An experiment was conducted to determine how an E. coli challenge and dietary clays affect the intestinal barrier of pigs. Two groups of 32 pigs (initial BW: 6.9 ± 1.0 kg) were distributed in a 2 × 4 factorial arrangement of a randomized complete block design (2 challenge treatments: sham or E. coli, and 4 dietary treatments: control, 0.3% smectite A, 0.3% smectite B and 0.3% zeolite), with 8 replicates total. Diarrhea score, growth performance, goblet cell size and number, bacterial translocation from intestinal lumen to lymph nodes, intestinal morphology, and relative amounts of sulfo and sialo mucins were measured. The E. coli challenge reduced performance, increased goblet cell size and number in the ileum, increased bacterial translocation from the intestinal lumen to the lymph nodes, and increased ileal crypt depth. One of the clays (smectite A) tended to increase goblet cell size in ileum, which may indicate enhanced protection. In conclusion, E. coli infection degrades intestinal barrier integrity but smectite A may enhance it.

Alternatives to antibiotics as growth promoters for use in swine production: a review

In the past two decades, an intensive amount of research has been focused on the development of alternatives to antibiotics to maintain swine health and performance. The most widely researched alternatives include probiotics, prebiotics, acidifiers, plant extracts and neutraceuticals such as copper and zinc. Since these additives have been more than adequately covered in previous reviews, the focus of this review will be on less traditional alternatives. The potential of antimicrobial peptides, clay minerals, egg yolk antibodies, essential oils, eucalyptus oil-medium chain fatty acids, rare earth elements and recombinant enzymes are discussed. Based on a thorough review of the literature, it is evident that a long and growing list of compounds exist which have been tested for their ability to replace antibiotics as feed additives in diets fed to swine. Unfortunately, the vast majority of these compounds produce inconsistent results and rarely equal antibiotics in their effectiveness. Therefore, it would appear that research is still needed in this area and that the perfect alternative to antibiotics does not yet exist.

Standardized ileal amino acid digestibility in egg from hyperimmunized hens fed to weaned pigs

The study was conducted to determine the apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of AA in egg from hens hyperimmunized with Escherichia coli K88 antigens (EGG) fed to weaned pigs. Spray dried porcine plasma (SDPP) was included for comparison. Eight barrows (Yorkshire-Landrace × Duroc; initial BW of 17 ± 1 kg) were fitted with a T-cannula at the distal ileum and fed 2 diets in a completely randomized design to give 4 replicates per diet. The diets were corn (Zea mays) starch based with either EGG or SDPP as the sole source of protein and were formulated to contain 130 g/kg CP. At the end of the study, a 50 g/kg casein diet was fed to all pigs (n = 8) to quantify endogenous N and AA losses to determine SID. Titanium dioxide (3 g/kg) was included in the diets as an indigestible maker. Each period lasted for 7 d. Pigs were adapted to their respective diets for 5 d followed by 12 h of continuous ileal digesta collection on days 6 and 7. Daily feed allowance was set at 4% BW at the beginning of each period and offered in 2 equal portions at 0800 and 1600 h as a dry mash. Pigs had unlimited access to water via low pressure nipple drinkers. The AID (%) of CP and indispensable AA were lower (P < 0.05) in EGG compared with SDPP. The SID (%) of CP (82 vs. 96) and indispensable AA were lower (P < 0.05) in pigs fed EGG compared with SDPP. In conclusion, the average AID and SID of N and indispensable AA in EGG are lower than in SDPP when fed at high levels.

Response of piglets weaned from sows fed diets supplemented with conjugated linoleic acid (CLA) to an Escherichia coli K88+ oral challenge

Seventy-eight Cotswold piglets weaned from sows receiving 0% or 2% conjugated linoleic acid (CLA)-supplemented rations from day 85 of gestation through lactation were allocated to nursery diets (ND) according to their dam's lactation ration (LR) as follows (1) 0%-0% (0% CLA LR: 0% CLA ND, n = 17); (2) 0%-2% (0% CLA LR: 2% CLA ND, n = 17); (3) 2%-0% (2% CLA LR: 0% CLA ND, n = 23); and (4) 2%-2% (2% CLA LR: 2% CLA ND, n = 21). At 28 ± 2 days of age all piglets received an oral Escherichia coli K88+ (enterotoxigenic Escherichia coli, ETEC) challenge and were subsequently monitored for scour development and overall health until 36 ± 2 days of age, after which blood and tissue samples were collected. Piglet BW was not affected by dietary CLA supplementation to LR (P > 0.05). However, by day 36 piglets receiving 2% CLA-supplemented ND were significantly lighter (P < 0.05) than piglets receiving control diets. Average daily gain and feed efficiency were not affected by CLA supplementation. Average daily feed intake (ADFI) was greater for piglets weaned from 2% CLA-supplemented sows from day 17 to 28 (P < 0.05), otherwise ADFI was unaffected by dietary CLA supplementation (P > 0.05). The development of scours was less severe in piglets weaned from 2% CLA-supplemented sows at 8, 24, 48 and 56 h after ETEC challenge (P < 0.05). Intestinal coliform and lactic acid bacteria populations post challenge were not affected by CLA supplementation. However, cecal ammonia-N was numerically greatest in 0%-0% piglets compared to the other treatment groups, and the total volatile fatty acid production was numerically lower in 0%-0% and 0%-2% piglets compared to 2%-0% and 2%-2% piglets. In addition, piglets weaned from 2% CLA-supplemented sows had increased serum immunoglobulin A (P < 0.001) and G (P < 0.05) levels and reduced (P < 0.05) intestinal mucosal inflammation compared to piglets weaned from control sows. Although there were no obvious additional health effects observed when CLA was provided in ND, supplementing sow rations with 2% CLA from mid-gestation through weaning appears to have immune-stimulating carry-over effects post weaning. Thus, supplementing sow rations with CLA may be a practical strategy for enhancing passive immune transfer and improving the immune status and overall gut health of nursery piglets.

Impact of bioactive substances on the gastrointestinal tract and performance of weaned piglets: a review

The EU ban on in-feed antibiotics has stimulated research on weaning diets as a way of reducing post-weaning gut disorders and growth check in pigs. Many bioactive components have been investigated but only few have shown to be effective. Amongst these, organic acids (OA) have been shown to exert a bactericidal action mediated by non-dissociated OA, by lowering gastric pH, increasing gut and pancreas enzyme secretion and improving gut wall morphology. It has been postulated that they may also enhance non-specific immune responses and improve disease resistance. In contrast, relatively little attention has been paid to the impact of OA on the stomach but recent data show they can differently affect gastric histology, acid secretion and gastric emptying. Butyrate and precursors of butyric acid have received special attention and although promising results have been obtained, their effects are dependent upon the dose, treatment duration, initial age of piglets, gastrointestinal site and other factors. The amino acids (AA) like glutamine, tryptophan and arginine are supportive in improving digestion, absorption and retention of nutrients by affecting tissue anabolism, stress and (or) immunity. Glutamine, cysteine and threonine are important for maintaining mucin and permeability of intestinal barrier function. Spray-dried plasma (SDP) positively affects gut morphology, inflammation and reduces acquired specific immune responses via specific and a-specific influences of immunoglobulins and other bioactive components. Effects are more pronounced in early-weaned piglets and under poorer health conditions. Little interaction between plasma protein and antibiotics has been found, suggesting distinct modes of action and additive effects. Bovine colostrum may act more or less similarly to SDP. The composition of essential oils is highly variable, depending on environmental and climatic conditions and distillation methods. These oils differ widely in their antimicrobial activity in vitro and some components of weaning diets may decrease their activity. Results in young pigs are highly variable depending upon the product and doses used. These studies suggest that relatively high concentrations of essential oils are needed for beneficial effects to be observed and it has been assumed that these plant extracts mimic most of the effects of antibiotics active on gut physiology, microbiology and immunology. Often, bioactive substances protective to the gut also stimulate feed intake and growth performance. New insights on the effects of selected OA and AA, protein sources (especially SDP, bovine colostrum) and plant extracts with anti-bacterial activities on the gut are reported in this review.

Gastrointestinal health and function in weaned pigs: a review of feeding strategies to control post-weaning diarrhoea without using in-feed antimicrobial compounds

For the last several decades, antimicrobial compounds have been used to promote piglet growth at weaning through the prevention of subclinical and clinical disease. There are, however, increasing concerns in relation to the development of antibiotic-resistant bacterial strains and the potential of these and associated resistance genes to impact on human health. As a consequence, European Union (EU) banned the use of antibiotics as growth promoters in swine and livestock production on 1 January 2006. Furthermore, minerals such as zinc (Zn) and copper (Cu) are not feasible alternatives/replacements to antibiotics because their excretion is a possible threat to the environment. Consequently, there is a need to develop feeding programs to serve as a means for controlling problems associated with the weaning transition without using antimicrobial compounds. This review, therefore, is focused on some of nutritional strategies that are known to improve structure and function of gastrointestinal tract and (or) promote post-weaning growth with special emphasis on probiotics, prebiotics, organic acids, trace minerals and dietary protein source and level.

Effects of spray-dried animal plasma on serous and intestinal redox status and cytokines of neonatal piglets

The study investigated the effects of dietary supplementation with spray-dried animal plasma (SDAP) on growth performance, intestinal morphology, as well as serum and intestinal cytokines and antioxidant indicators of artificially reared neonatal piglets. Three diets, 1) control (a fish meal basal diet), 2) SDAP (containing 10% SDAP), and 3) autoclaved SDAP (auSDAP; containing 10% auSDAP), were fed to 36 weaned piglets (3 d old), which were randomly allotted to 3 groups. At 21 d of age, blood and intestinal mucosal samples were collected from all piglets after they were slaughtered. Compared with the control, both SDAP and auSDAP improved ADFI and duodenal villus height of piglets (P < 0.05), whereas SDAP increased ADG and duodenal villus height to crypt depth ratio (P < 0.05). Piglets fed SDAP and auSDAP had reduced malondialdehyde (MDA) content in mucosa (P < 0.05). The concentration of serum MDA was decreased and mucosal catalase (CAT) activities were increased in piglets fed SDAP diet than those fed the control diet (P < 0.05). In the mucosa, both SDAP and auSDAP decreased tumor necrosis factor α, IL-6, transforming growth factor β, and soluble IL-2 receptor contents (P < 0.05). Mucosal IL-1β was decreased in SDAP compared with auSDAP and control groups (P < 0.05). The SDAP and control groups had increased mucosal IL-2 compared with auSDAP group (P < 0.05). The cytokines in serum were not affected by SDAP and auSDAP. The results indicate that both SDAP and auSDAP improved the growth performance of neonatal piglets, whereas the SDAP had a greater effect. The benefits of SDAP probably resulted from the promotion of the intestinal development, which were accompanied by the increased antioxidant capacity and the decreased production of inflammatory factors in the intestinal mucosa.

Effects of dietary protein level and zinc oxide supplementation on performance responses and gastrointestinal tract characteristics in weaner pigs challenged with an enterotoxigenic strain of Escherichia coli

The interactive effects of dietary protein level, zinc oxide (ZnO) supplementation and infection with an enterotoxigenic strain of Escherichia coli (ETEC) on performance responses and gastrointestinal tract characteristics were examined. Ninety-six individually housed, 21-day-old pigs (1 : 1 gender ratio) with initial bodyweight (BW) of 7.2 ± 0.69 kg, were used in a split plot experiment, with the whole plot being challenge or no challenge with ETEC and the dietary treatments used as subplots and arranged in a completely randomised 2 × 2 factorial design, with the factors being (i) two dietary protein levels (251 versus 192 g/kg crude protein) and (ii) addition or no addition of 2.5 g/kg ZnO. No antibiotic was added to the diet. The ETEC infection decreased average daily gain (P < 0.001) and increased feed conversion ratio (P < 0.01). Protein level had no effect on performance of pigs while ZnO supplementation increased (P < 0.001) average daily gain and average daily feed intake and hence decreased feed conversion ratio (P < 0.001). There were no 2- or 3-way interactions for growth performance indices (P > 0.05). Feeding a lower protein diet did not influence (P > 0.05) faecal volatile fatty acid concentrations. In non-infected pigs, feeding a lower protein diet caused a lower pH in the jejunum and ileum compared with pigs fed a higher protein diet (P < 0.05 and P < 0.01, respectively). However, feeding ZnO-supplemented diets increased (P < 0.05) the pH in the stomach and caecum compared with feeding diets without ZnO supplementation. Protein level did not alter (P > 0.05) empty BW but dietary supplementation with ZnO increased empty BW (P < 0.05). Neither protein level nor ZnO supplementation modified small intestinal morphology, although a tendency for an interaction (P < 0.1) was detected for jejunal villous height between protein level and ZnO supplementation. The results indicate that feeding ZnO-supplemented diets improved pig performance, and feeding a lower protein diet without ZnO supplementation did not compromise performance nor modify measures of gastrointestinal tract structure and function compared with pigs fed a diet higher in protein after weaning.

Effects of in-feed egg yolk antibodies on Salmonella shedding, bacterial antibiotic resistance, and health of pigs

To determine effects of anti-Salmonella egg yolk antibodies on shedding and antibiotic resistance of Salmonella enterica Typhimurium, newly weaned pigs were randomly assigned to six dietary treatments. These treatment groups were (i) a control (basal) diet without additives and similar diets with (ii) egg yolk powder derived from chickens challenged with Salmonella Typhimurium antigens, (iii) a commercial egg yolk powder control, (iv) apramycin for 14 days followed by carbadox, (v) oxytetracycline, or (vi) spray-dried plasma protein. Treatments were provided beginning on day 3 of the trial, and all pigs were challenged with 5 ml of 10(8) CFU/ml Salmonella Typhimurium on day 7. Fecal samples were collected on days 0, 7, 8, 12, 14, 21, 58, 88, and 118 for isolation of Salmonella and Escherichia coli to determine shedding and antibiotic resistance patterns. Body weights, white blood cell counts, and plasma concentrations of anti-Salmonella immunoglobulin G and porcine interleukin 1beta were analyzed as indicators of animal health. The percentage of pigs shedding Salmonella was lower for antibiotic treatment groups compared with other groups; however, resistance was greater in E. coli from pigs fed antibiotics than in pigs in other treatment groups. Health and performance indicators (pig weight gains, white blood cell counts, and plasma concentrations of anti-Salmonella antibodies) did not differ between treatment groups. These studies indicate that feeding egg yolk containing anti-Salmonella immunoglobulin Y may not be effective in controlling shedding of Salmonella in pigs.

Orally administered ovine serum immunoglobulins influence growth performance, organ weights, and gut morphology in growing rats

In this study, our aim was to determine whether orally administered ovine serum Ig improved growth performance, organ weights, and gut morphology in growing rats and whether the method of manufacture of ovine serum Ig affected its bioactivity. Ninety Sprague-Dawley male rats were used in a 21-d growth study and were fed a basal control diet (BD; no Ig) and 5 test diets: spray-dried porcine plasma (SDPP), freeze-dried ovine Ig (FDOI), 2 concentrations of spray-dried ovine Ig (SDOI(100) and SDOI(150)), and inactivated ovine Ig (IOI). Diets were isocaloric and contained the same amount of the first limiting amino acids, methionine plus cysteine. The body weight gain:feed ratio was higher (P < 0.05) for the FDOI-fed rats than for the BD- and IOI-fed groups. FDOI rats had higher jejunum (P < 0.05) and colon weights (P < 0.05) at the end of the study than rats in the BD group. Compared with the SDOI(100)-fed group, the FDOI group supported higher (P < 0.05) duodenum and colon weights. For gut morphology, the FDOI and the BD and IOI groups differed (P < 0.05). The FDOI-fed rats had longer (P < 0.05) villi and greater villi surface areas in the duodenum, jejunum, and ileum than the rats fed SDOI(100). An ovine Ig fraction selectively improved growth performance, organ weight, and gut morphology in growing rats. Compared with spray-drying, a freeze-drying procedure appears to preserve a higher degree of immunological activity.

The in vitro anti-pathogenic activity of immunoglobulin concentrates extracted from ovine blood

An immunoglobulin-rich fraction has been prepared from ovine blood in our laboratory. We have investigated its antibacterial activity and binding activity to pathogenic whole cell antigens, lipopolysaccharide (LPS) and staphylococcal enterotoxin B. Ovine immunoglobulin concentrate (OIC) comprised about 73 +/- 2% of IgG and 11 +/- 1% of IgM on a protein basis. It inhibited the growth of all 13 strains of pathogens tested, but the inhibitory activity varied according to bacterial strain. The inhibitory activity of OIC was attributed to the high contents of undenatured immunoglobulin present because its inhibitory activity was destroyed by pepsin digestion and heat treatment (65 degrees C for 30 min). OIC bound to all the Gram-positive and Gram-negative pathogens, regardless of cell wall structure. The highest magnitude of crossreactivity to whole cell antigens was against Staphylococcus epidermidis and Shigella soneii strains (p < 0.001). The binding activity of OIC to LPS obtained from Escherichia coli O111:B4 and Salmonella enterica serotype typhimurium was assessed by enzyme-linked immunosorbent assay and lymphoblast K-562 proliferation assay. OIC bound to LPS with a binding activity that was dependent on OIC concentration and saturable, showing typical hyperbolic curves. For toxin-binding activity, an OIC concentration-dependent trend like that for LPS-binding activity was also observed. This preliminary evidence suggests that the OIC used in this study could be a promising supplement for protecting against pathogenic bacteria.

Dietary specific antibodies in spray-dried immune plasma prevent enterotoxigenic Escherichia coli F4 (ETEC) post weaning diarrhoea in piglets

In order to establish the mechanism of spray dried plasma powder (SDPP) in improving pig health and performance, a diet containing either 8% SDPP, spray dried immune plasma powder (SDIPP), or control protein (soybean and whey) ration was fed to piglets in an experimental model of enterotoxigenic Escherichia coli F4 (ETEC) post-weaning diarrhoea (PWD). SDIPP was obtained from pigs immunized with a vaccine containing ETEC fimbrial subunit F4 and heat-labile toxin (LT), and SDPP from non-immunized controls. Average daily growth (ADG) was determined, and daily samples of rectal faeces were assessed for diarrhoea (as percentage of dry matter), and ETEC excretion (in CFU/g). SDPP and SDIPP significantly (p<0.05) reduced diarrhoea, and SDIPP significantly reduced ETEC excretion. ADG was not significantly (p>0.05) affected. After the experiment, 30% of piglets tested F4 receptor positive (F4R+). A significant correlation between F4R status and morbidity was found. In F4R+ animals, SDIPP significantly improved diarrhoea and ADG, and decreased ETEC excretion, and SDPP significantly improved diarrhoea and ADG. Surprisingly, SDPP reduced diarrhoea in F4R+ animals without significant reduction of ETEC excretion, which is most likely related to the presence of anti-LT antibodies in SDPP. The results show that oral protection against ETEC by SDPP is attributable to spontaneous antibodies, in this case anti-LT antibodies. Furthermore, the results indicate that the combination of anti-LT and anti-F4 antibodies as in SDIPP is most effective in ETEC prevention. Finally, the F4R distribution in the herd should be taken into account to correctly assess efficacy.