How to control necrotic enteritis through gut health optimization

Antibiotic growth promoters (AGPs) have routinely been used in intensive poultry production for improving birds’ performance. However, in recent years, reducing the use of antibiotics in animal production has become a top priority, due to concerns about the development of antibiotic-resistant bacteria and mounting consumer pressure. Multiple countries have introduced bans or severe restrictions on the non-therapeutic use of antibiotics, including in the US, where the Food and Drug Administration has implemented measures to curb the use of antibiotics since 2017.

However, the removal of AGPs poses challenges for poultry performance, including reduced feed efficiency, decreased daily weight gain, as well as higher mortality. Moreover, the withdrawal of AGPs in feed is widely recognized as one of the predisposing factors for necrotic enteritis (NE). NE is one of the most common and economically important poultry diseases, with an estimated global impact of US$ 5 to 6 billion per year. As a result of withdrawing AGPs, the usage of therapeutic antibiotics to treat NE has increased. To break out of this vicious cycle and to secure the efficiency of poultry production, alternatives are needed that combat NE where it starts: in the gut.

Necrotic enteritis: a complex disease

NE is caused by pathogenic strains of Clostridium perfringens (CP): ubiquitous, gram-positive, spore-forming anaerobic bacteria. The spores of CP can be found in poultry litter, feces, soil, dust, and contaminated feed. Low levels of different CP strains are naturally present in the intestines of healthy birds, kept in check by a balanced microbiome. However, when gut health is compromised, pathogenic strains can proliferate at the expense of unproblematic strains, resulting in clinical or sub-clinical NE.

Animals suffering from the clinical form show symptoms such as general depression, reluctance to move, and diarrhea, with mortality rates of up to 50%. Infected birds suffer from degenerated mucosa lesions in the small intestines. Even in its “mild”, subclinical form, which often goes unnoticed, the damage to the animals’ intestinal mucosa can result in permanently reduced performance and consequent economic losses for the producer.

Certain predisposing factors have been found to enable the proliferation of pathogenic strains in the gastrointestinal tract. Diet is a key example: the composition of the gut flora is directly linked to feed composition. High inclusion rates of cereals (barley, rye, oats, and wheat) that contain high levels of non-starch polysaccharides (NSPs), high levels of indigestible protein, and inclusion of proteins of animal origin (e.g. fishmeal) have been shown to predispose birds to NE.

A range of diseases (e.g. chicken infectious anemia, Gumboro, and Marek’s disease), but also other factors that have immunosuppressive effects, such as heat or cold stress, mycotoxins, feed changes, or high stocking density, render birds more susceptible to intestinal infections. The single most prominent predisposing factor for the occurrence of NE is the mucosal damage caused by coccidiosis.

Gut health is key to combating necrotic enteritis

To control NE, a holistic approach to optimizing the intestinal health of poultry is needed. It should take into account not only parameters such as diet, hygiene, and stress, but should also make use of innovative tools.

Phytomolecules, also known as secondary plant compounds, are essentially plants’ defense mechanisms against pathogens such as moulds, yeasts, and bacteria. Studies have demonstrated the antimicrobial effects of certain phytomolecules, including against antibiotic-resistant pathogens. Phytomolecules have also been found to boost the production of digestive enzymes, to suppress pro-inflammatory prostaglandins and have antioxidant properties. These features make them a potent tool for optimizing gut health, potentially to the point of replacing AGPs.

Can phytomolecules mitigate the impact of necrotic enteritis?

To study the impact of phytomolecules on the performance of broilers challenged with a NE-causing CP strain, a trial was conducted at a US-based research facility. In this 42-day study, 1050 male day-old Cobb 500 broiler chicks were divided into 3 groups, with 7 replicates of 50 chicks each.

On the first day, all animals were vaccinated against coccidiosis through a live oocyst spray vaccination. The experimental diets met or exceeded the National Research Council requirements, and were fed as crumbles/pellets. On days 19, 20, and 21, all pens, except the negative control group, were challenged with a broth culture of C. perfringens. A field isolate of CP known to cause NE (originating from a commercial broiler operation) was utilized as the challenge organism. On day 21, three birds from each pen were selected, sacrificed, group weighed, and examined for the degree of present NE lesions.

The positive control group received no supplements. The trial group received a synergistic combination of two phytogenic products containing standardized amounts of selected, microencapsulated phytomolecules: an in-feed phytogenic premix (Activo®, EW Nutrition GmbH) and a liquid complementary feed supplied via the drinking water (Activo® Liquid, EW Nutrition GmbH). The products were given at inclusion rates corresponding to the manufacturer’s baseline antibiotic reduction program recommendations (Figure 1):

Figure 1: Trial design

The trial results indicate that the addition of phytomolecules helps to mitigate the impact of NE on broilers’ performance. The group receiving Activo® and Activo® Liquid showed a better feed conversion (Figure 2) compared to the positive control group (NE challenge, no supplement). Also, better lesion scores were noted for animals receiving phytomolecules (0.7 and 1) than for the positive control group (1.6).

The most significant effect was observed concerning mortality: the group receiving Activo® and Activo® Liquid showed a 50% lower mortality rate than the positive control group (Figure 3). These results clearly indicate that phytomolecules can play an important role in mitigating losses due to NE.

Figure 1: Adjusted FCR

Figure 2: Lesion scores and mortality

Tackling necrotic enteritis in a sustainable way

In an age of AGP-free poultry production, a concerted focus on fostering animals’ gut health is key to achieving optimal performance. This study strongly demonstrates that, thanks to their antimicrobial, digestive, anti-inflammatory and antioxidant properties, phytomolecules effectively support birds’ intestinal health when challenged with NE. The inclusion of Activo® and Activo® Liquid, two phytogenic products designed to synergistically support birds during critical periods, resulted in improved feed conversion, better lesion scores, and 50% lower mortality.

In combination with good dietary, hygiene, and management practices, phytomolecules are therefore a potent tool for reducing the use of antibiotics: including Activo® and Activo® Liquid in their animals’ diets allows poultry producers to reduce the incidence of NE, to mitigate its economic impact in case of outbreaks, and therefore to control NE in a sustainable way.

By A. Bhoyar, T. van Gerwe and S. Regragui Mazili

Respiratory Challenges & Their Natural solutions

Respiratory Challenges: Breathing Space for Antibiotic Reduction?

Sub-therapeutic doses of antibiotic growth promoters (AGPs) were used for more than 50 years in poultry production to achieve performance targets – until growing concerns arose regarding antibiotic resistance (Kabir, 2009) and decreasing efficacy of antibiotics for medical purposes (Dibner & Richards, 2005).
Isolates of ESBL-producing E.coli from animals, farmworkers, and the environment were found to have identical multidrug resistance patterns (A. Nuangmek et al., 2018). There is also evidence that AMR strains of microorganisms spread from farm animal to animal workers and beyond. Global AMR fatalities are increasing and might reach 10 million by 2050 (Mulders et al., 2010, Trung et al., 2017, Huijbers et al., 2014).
In light of this, certain AGPs have already been banned, and there is a strong possibility of future restrictions on their use worldwide. Bans are effective: the MARAN report 2018 shows that lower antibiotics usage following the EU ban on AGPs has reduced resistant E.coli in broilers. Another positive consideration is the market opportunities that exist for antibiotic residue-free food.
However, the key element that poultry producers need to get right for antibiotic reduction to be successful is respiratory health management. This article looks at why respiratory health is a particular challenge – and how phytogenic solutions can help.

A closer look at the chickens’ respiratory system

The respiratory tract is equipped with a functional mucociliary apparatus consisting of a protective mucous layer, airway surface liquid layer, and cilia on the surface of the ciliated cells. This apparatus produces mucus, which traps the inhaled particles and pathogens and propels them out of the airways. This mechanism, called the mucociliary clearance, is the primary innate defense mechanism of the respiratory system.
High stocking density combined with stressful environmental factors can negatively influence birds’ immune systems (Heckert et al., 2002; Muniz et al., 2006), making them more susceptible to respiratory disease. When a bird suffers from respiratory disease, which is nowadays usually complicated by a co-infection or secondary bacterial infection, there is an excess production of mucus that results in ciliostasis and, therefore, in an impaired mucociliary clearance. The excess mucus in the tract obstructs the airways by forming plagues and plugs, resulting in dyspnea (hypoxia) and allowing the invasive bacteria to adhere and colonize the respiratory system.
The build-up of mucus in the respiratory tract severely reduces oxygen intake, causing breathlessness, reduced feed intake, and a drop in the birds’ energy levels, which negatively impacts weight gain and egg production. Respiratory problems can result from infection with bacteria, viruses, and fungi, or exposure to allergens. The resultant irritation and inflammation of the respiratory tract leads to sneezing, wheezing, and coughing – and, therefore, the infection rapidly spreads within the flock.

Relatively high stocking density is the norm in poultry production

Low or no antibiotics: how to manage respiratory disease?

Unsurprisingly, respiratory diseases in poultry are a major cause of mortality and economic loss in the poultry industry. For Complicated Chronic Respiratory Disease (CCRD), for instance, although the clinical manifestations are usually slow to develop, Mycoplasma gallisepticum (MG), in combination with E. coli, can cause severe airsacculitis. Beside feed and egg production reduction, these problems are of high economic significance since respiratory tract lesions can cause high morbidity, high mortality, and significant carcass condemnation and downgrading.
Producers need to pre-empt the spread of respiratory pathogens, react quickly to alleviate respiratory distress and maintain the mucociliary apparatus’ functionality. Traditionally, treatment options are based on antiviral, anti-inflammatory, and antibiotic drugs. Can the poultry industry limit losses from respiratory infections without excessive recourse to antibiotics?
Indeed, a sudden reduction in antibiotic usage comes with a risk of impaired performance, increased mortality, and impaired animal health and welfare. The impact has been quantified as a 5% loss in broiler meat production per sq. meter (Gaucher et al., 2015). Effective antibiotics reduction requires a combination of innovative products and suitable consultancy services to manage poultry gut health, nutrition, flock management, biosecurity, and, particularly, respiratory health.
Non-antibiotic alternatives to control diseases and promote broiler growth, such as organic acids (Vieira et al., 2008), probiotics (Mountzouris et al., 2010), prebiotics (Patterson & Burkholder, 2003), and essential oils (Basmacioğlu Malayoğlu et al., 2010) have been the subject of much research in recent years.

Phytogenic solutions: proven efficacy

Essential oils, which are extracted from plant parts, such as flowers, buds, seeds, leaves, twigs, bark, wood, fruits, and roots, have a particularly well-established track record of medicinal applications. Efforts have centered on phytomolecules, the biologically active secondary metabolites that account for the properties of essential oils (Hernández et al., 2004; Jafari et al., 2011).
Studying these properties is challenging: essential oils are very complex natural mixtures of compounds whose chemical compositions and concentrations are variable. For example, the concentrations of the two predominant phytogenic components of thyme essential oils, thymol and carvacrol, have been reported to range from as low as 3% to 60% of the whole essential oil (Lawrence and Reynolds, 1984).
Another well-researched example is eucalyptus oil. The essential oils of eucalyptus species show antibacterial, anti-inflammatory, diaphoretic, antiseptic, analgesic effects (Cimanga et al., 2002) and antioxidant properties (Lee and Shibamoto, 2001; Damjanović Vratnica et al., 2011). The oils are mainly composed of terpenes and terpene derivatives in addition to some other non-terpene components (Edris, 2007). The principal constituent found in eucalyptus is 1,8-cineole (eucalyptol); however, other chemotypes such as α-phellandrene, ρ-cymene, γ-terpinene, ethanone, and spathulenol, among others, have been documented (Akin et al., 2010).

Close-up of eucalyptus leaf oil glands and the molecular structure of eucalyptol C₁₀H₁₈O (red = oxygen; dark grey = carbon; light grey = hydrogen)

ANTIMICROBIAL ACTIVITY

In modern intensive broiler production, bacterial diseases such as salmonellosis, colibacillosis, mycoplasmosis, or clostridia pose serious problems for the respiratory system and other areas. Analyses of the antibacterial properties of essential oils have been carried out by multiple research units (Ouwehand et al., 2010; Pilau et al., 2011; Solorzano- Santos and Miranda-Novales, 2012; Mahboubi et al., 2013; Nazzaro et al., 2013; Petrova et al., 2013).
Phenols, alcohols, ketones, and aldehydes are clearly associated with antibacterial activity; the exact mechanisms of action, however, are not yet fully understood (Nazzaro et al., 2013). Essential oils’ antimicrobial activity is not attributable to a unique mechanism but instead results from a cascade of reactions involving the entire bacterial cell (Nazzaro et al., 2013). However, it is accepted that antimicrobial activity depends on the lipophilic character of the components.
The components permeate the cell membranes and mitochondria of the microorganisms and inhibit, among others, the membrane-bound electron flow and thus the energy metabolism. This leads to a collapse of the proton pump and draining of the ATP (adenosine triphosphate) pool. High concentrations may also lead to lysis of the cell membranes and denaturation of cytoplasmic proteins (Nazzaro et al., 2013; Gopi et al., 2014).
According to current knowledge, lavender, thyme, and eucalyptus oil, as well as the phytomolecules they contain, show enhanced effects when combined with other essential oils or synthetic antibiotics (Sadlon and Lamson, 2010; Bassole and Juliani, 2012; Sienkiewicz, 2012; de Rapper et al., 2013; Zengin and Baysal, 2014).
Minimum inhibitory concentration (MIC) of some essential oil components against microorganisms in vitro

IMMUNE SYSTEM BOOST I: IMPROVED PRODUCTION OF ANTIBODIES

Some essential oils were found to influence the avian immune system positively, since they promote the production of immunoglobulins, enhance the lymphocytic activity, and boost interferon-γ release (Awaad et al., 2010; Faramarzi et al., 2013; Gopi et al., 2014; Krishan and Narang, 2014). Placha et al. (2014) showed that the addition of 0.5g of thyme oil per kg of feed significantly increased IgA levels.
Awaad et al. (2010) experimented on birds vaccinated with the inactivated H5N2 avian influenza vaccine. The experiment revealed that adding eucalyptus and peppermint essential oils to the water at a rate of 0.25 ml per liter resulted in an enhanced cell-mediated and humoral immune response.
Saleh et al. (2014), who applied thyme and ginger oils in quantities of 100mg and 200mg per kg of feed, respectively, observed an improvement in chickens’ immunological blood profile through increased antibody production. Rehman et al. (2013) stated that the use of herbal products containing eucalyptus oil and menthol in broilers showed consistently higher antibody titers against NDV (Newcastle disease virus), compared to untreated broilers.

IMMUNE SYSTEM BOOST II: BETTER VACCINE RESPONSES AND ANTI-INFLAMMATORY EFFECTS

Essential oils are also used as immunomodulators during periods when birds are exposed to stress, acting protectively and regeneratively. Importantly, the oils alleviate the stress caused by vaccination (Barbour et al., 2011; Faramarzi et al., 2013; Gopi et al., 2014). The study by Kongkathip et al. (2010) confirmed the antiviral activity of turmeric essential oil.
In recent years studies have been carried out on the use of essential oils in conjunction with vaccination programs, including those against infectious bronchitis (IB), Newcastle disease, and Gumboro disease. The results of the experiments show that essential oils promote the production of antibodies, thus enhancing the efficacy of vaccination (Awaad et al., 2010; Barbour et al., 2010; Barbour et al., 2011; Faramarzi et al., 2013).
Essential oils contain compounds that are known to possess strong anti-inflammatory properties, mainly terpenoids, and flavonoids, which suppress the metabolism of inflammatory prostaglandins (Krishan and Narang, 2014). Also, other compounds found in essential oils have anti-inflammatory, pain-relieving, or edema-reducing properties, for example, linalool from lavender oil, or 1,8-cineole, the main component of eucalyptus oil (Peana et al., 2003).

IMMUNE SYSTEM BOOST III: ANTIOXIDANT EFFECTS AND RADICAL SCAVENGING

An imbalance in the rate of production of free radicals or removal by the antioxidant defense mechanisms leads to a phenomenon referred to as oxidative stress. A mixture of Oregano (carvacrol, cinnamaldehyde, and capsicum oleoresin) was found to beneficially affect the intestinal microflora, absorption, digestion, weight gain and also to have an antioxidant effect on chickens (Bassett, 2000).
Zeng et al. (2015) indicated the positive effect of essential oils on the production of digestive secretions and nutrient absorption. They reduce pathogenic stress in the gut, exert antioxidant properties, and reinforce the animal’s immune status.
Inside the cell, essential oils can serve as powerful scavenger preventing mutations and oxidation (Bakkali et al., 2008). Studies have demonstrated the concentration-dependent free radical scavenging ability of oils from eucalyptus species (Kaur et al., 2010; Marzoug et al., 2011; Olayinka et al., 2012). Some authors attribute the strong antioxidant capacity of essential oils to their phenolic constituents and synergistic effect between tannins, rutin, thymol, and carvacrol, and probably 1, 8-cineole. Moderate DPPH radical scavenging activity reported by Edris(2007), El-Moein et al. (2012), and Kaur et al. (2011).
Vázquez et al. (2012) have demonstrated the potential of the phenolic compounds in eucalyptus bark as a source of antioxidant compounds. The study showed that eucalyptus had ferric reducing antioxidant power in the ranges 0.91 to 2.58 g gallic acid equivalent (GAE) per 100 g oven-dried bark and 4.70 to 11.96 mmol ascorbic acid equivalent (AAE) per 100 g oven-dried bark, respectively (see also Shahwar et al., 2012). Moreover, Eyles et al. (2004) were able to show superoxide dismutase (SOD)-like activity for different compounds and fractions isolated from wood extracts.

LAST BUT NOT LEAST: POSITIVE EFFECTS ON THE RESPIRATORY SYSTEM

In poultry production houses, especially in summer, high temperatures and low humidity increase the amount of air dust. Under such conditions, respiratory tract disorders in broiler chickens, including the deposition of particulates, become more frequent and more severe.

Clinical signs of respiratory disease in chickens include coughing, sneezing, and rales

Thyme oil, thanks to the phytomolecules thymol and carvacrol, supports the treatment of respiratory disorders. These substances smooth tightened muscles and stimulate the respiratory system. An additional advantage lies in their expectorant and spasmolytic properties (Edris, 2007).
These properties are also seen in essential oils such as eucalyptus and peppermint, which contain eucalyptol and menthol. They thin out the mucus and facilitate its removal from the airways. As a result, the airways are cleared and breathing during inflammation becomes easier (Durmic and Blache, 2012).
Another positive effect of the terpenoid compounds used in commercial preparations for poultry is that they disinfect the bronchi, preventing respiratory infections (Awaad et al., 2010; Barbour et al., 2011; Mahboubi et al., 2013). Barbour and Danker (2005) reported that the essential oils of eucalyptus and peppermint improved the homogeneity of immune responses and performance in MG/H9N2-infected broilers.

Grippozon: the phytogenic solution for respiratory health

Grippozon is a liquid composition with a high content of essential oils, which are combined to systematically prevent and ease respiratory diseases. The formulation is derived from the research on essential oils’ effectiveness against respiratory pathogens that are common in animal farming. Grippozon exhibits a synergistic action of all its components to optimally support animal health. It contains a high concentration of active components; both their quantity and quality are guaranteed to deliver results.

APPLICATION OF GRIPPOZON

Grippozon application can be flexibly adapted to most common housing systems. It is fully water-soluble for use in the drinking line and it is also possible to nebulize a diluted solution in air.
The dose recommendation in drinking water usually amounts to 100ml to 200ml per 1000 liters of drinking water (Grippozon administration has not been reported to affect water consumption). The active substances in Grippozon adhere to mouth mucosa and become volatile in the breathing air later on. Therefore Grippozon can enter the respiratory system indirectly as well. The volatile compounds also spread into the whole barn air and, thus, indirectly via breathing into the respiratory system (and farmers notice the smell of essential oils when Grippozon is applied through in the waterline)
Grippozon can also be used as a spray at a rate of 200ml/10 liters of water for 2000 birds, twice daily on 2-3 days a week. This produces a very effective nebulization effect and offers faster respiratory relief to birds.
Grippozon is an impactful tool for managing respiratory problems. Thanks to its effective mucolytic and relaxant activity, Grippozon gives symptomatic relief to the birds during high-stress periods of respiratory diseases. Mucus in the trachea works as media for the proliferation of bacteria and viruses, so by thinning the mucus, Grippozon slows down the proliferation of bacteria and the spread of disease. Grippozon helps in improving air quality and air intake. It can also be used to stimulate the immune response during vaccination.

Authors:
Ruturaj Patil – Product Manager Phytogenic Liquids
Kowsigaraj Palanisamy – Global Validation Trial Manager

Strangles in Horses(Distemper)

Strangles in Horses

(Distemper)

By 

Bonnie R. Rush

, DVM, MS, DACVIM, Equine Internal Medicine, College of Veterinary Medicine, Kansas State University

Strangles is an infectious, contagious disease of Equidae characterized by abscessation of the lymphoid tissue of the upper respiratory tract. The causative organism, Streptococcus equi equi, is highly host-adapted and produces clinical disease only in horses, donkeys, and mules. It is a gram-positive, capsulated β-hemolytic Lancefield group C coccus, which is an obligate parasite and a primary pathogen.

Etiology and Pathogenesis:

S equi equi is highly contagious and produces high morbidity and low mortality in susceptible populations. Transmission occurs via fomites and direct contact with infectious exudates. Carrier animals are important for maintenance of the bacteria between epizootics and initiation of outbreaks on premises previously free of disease. Survival of the organism in the environment depends on temperature and humidity; it is susceptible to desiccation, extreme heat, and exposure to sunlight and must be protected within mucoid secretions to survive. Under ideal environmental circumstances, the organism can survive ~4 wk outside the host. Under field conditions, most organisms do not survive 96 hr.

Clinical Findings:

Streptococcus equi retropharyngeal abscess, horse

COURTESY OF DR. BONNIE R. RUSH.

Strangles, brain abscess, horse

COURTESY OF DR. SAMEEH M. ABUTARBUSH.

The incubation period of strangles is 3–14 days, and the first sign of infection is fever (103°–106°F [39.4°–41.1°C]). Within 24–48 hr of the initial fever spike, the horse will exhibit signs typical of strangles, including mucoid to mucopurulent nasal discharge, depression, and submandibular lymphadenopathy. Horses with retropharyngeal lymph node involvement have difficulty swallowing, inspiratory respiratory noise (compression of the dorsal pharyngeal wall), and extended head and neck. Older animals with residual immunity may develop an atypical or catarrhal form of the disease with mucoid nasal discharge, cough, and mild fever. Metastatic strangles (“bastard strangles”) is characterized by abscessation in other lymph nodes of the body, particularly the lymph nodes in the abdomen and, less frequently, the thorax. S equi is the most common cause of brain abscess in horses, albeit rare.

Diagnosis:

Diagnosis is confirmed by bacterial culture of exudate from abscesses or nasal swab samples. CBC reveals neutrophilic leukocytosis and hyperfibrinogenemia. Serum biochemical analysis is typically unremarkable. Complicated cases may require endoscopic examination of the upper respiratory tract (including the guttural pouches), ultrasonographic examination of the retropharyngeal area, or radiographic examination of the skull to identify the location and extent of retropharyngeal abscesses.

Treatment:

The environment for clinically ill horses should be warm, dry, and dust-free. Warm compresses are applied to sites of lymphadenopathy to facilitate maturation of abscesses. Facilitated drainage of mature abscesses will speed recovery. Ruptured abscesses should be flushed with dilute (3%–5%) povidone-iodine solution for several days until discharge ceases. NSAIDs can be administered judiciously to reduce pain and fever and to improve appetite in horses with fulminant clinical disease. Tracheotomy may be required in horses with retropharyngeal abscessation and pharyngeal compression.

Ruptured submandibular abscesses, horse

COURTESY OF DR. BONNIE R. RUSH.

Antimicrobial therapy is controversial. Initiation of antibiotic therapy after abscess formation may provide temporary clinical improvement in fever and depression, but it ultimately prolongs the course of disease by delaying maturation of abscesses. Antibiotic therapy is indicated in cases with dyspnea, dysphagia, prolonged high fever, and severe lethargy/anorexia. Administration of penicillin during the early stage of infection (≤24 hr of onset of fever) will usually arrest abscess formation. The disadvantage of early antimicrobial treatment is failure to mount a protective immune response, rendering horses susceptible to infection after cessation of therapy. If antimicrobial therapy is indicated, procaine penicillin (22,000 IU/kg, IM, bid) is the antibiotic of choice. Untreated guttural pouch infections can result in persistent guttural pouch empyema with or without chondroid formation.

Prevention:

Postexposure immunity is prolonged after natural disease in most horses, and protection is associated with local (nasal mucosa) production of antibody against the antiphagocytic M protein. The clinical attack rate of strangles is reduced by 50% in horses vaccinated with IM products that do not induce mucosal immunity. Local (mucosal) production of antibody requires mucosal antigen stimulation. An intranasal vaccine containing a live attenuated strain of S equi equi was designed to elicit a mucosal immunologic response. This attenuated strain is not temperature sensitive (inactivated by core body temperature) like the intranasal influenza vaccine. Reported complications include S equi equi abscesses at subsequent IM injection sites (live bacteria on hands of administrator), submandibular lymphadenopathy, serous nasal discharge, and purpura hemorrhagica.

Control:

Clinically affected horses should be physically separated from the herd and cared for by separate caretakers wearing protective clothing. The rectal temperature of all horses exposed to strangles should be obtained twice daily, and horses developing fever should be isolated (and potentially treated with penicillin). Contaminated equipment should be cleaned with detergent and disinfected using chlorhexidine gluconate or glutaraldehyde. Flies can transmit infection mechanically; therefore, efforts should be made to control the fly population during an outbreak. Farriers, trainers, and veterinarians should wear protective clothing or change clothes before traveling to the next equine facility. Additions to the herd should be carefully scrutinized for evidence of disease or shedding (nasopharyngeal culture) and quarantined for 14–21 days. Two negative nasal swab cultures should be obtained during the quarantine period.

Most horses continue to shed S equi for ~1 mo after recovery. Three negative nasopharyngeal swabs, at intervals of 4–7 days, should be obtained before release from quarantine, and the minimal isolation period should be 1 mo. Prolonged bacterial shedding (as long as 18 mo) has been identified in a small number of horses. Guttural pouch empyema is the source of infection in most prolonged carrier states. Bacterial culture of nasopharyngeal swab and/or guttural pouch lavage is used to identify persistent carriers.

Feeding Strategies in robotic dairies

Robotic milking

Milking is a predictable physical task that can be automatized easily. The milking center is the heart and center of a dairy, and yet labor intensive normally working almost 24-7 year-round. This, coupled with a challenged workforce, makes the milking center one of the most difficult areas to manage in larger dairy farms. In addition, potential communication and cultural barriers can complicate the relationship between dairy owners, managers and employees. For these reasons, robotic milking is becoming popular in dairy farms. It has been reported there are over 35,000 robotic units on farms worldwide.

The University of Minnesota Extension team reported that the top 3 reasons for installing a milking robot were improved lifestyle, reduced hired labor, and the ability to grow without additional hired labor. Along with feeding the cows, cleaning the facilities, and taking care of cow’s health and reproduction, fetching cows is one of the main task in robotic dairies. It has been reported that, on average, 8% of the cows must be fetched to the robots, and dairy workers spent 51 min/day/robot fetching cows.

Performance efficiency in robotic dairies

Three recent studies published in the Journal of Dairy Science evaluated the performance efficiency of automatic milking systems in North American dairy farms. In the first study, researchers from the School of Veterinary Medicine at the University of Wisconsin-Madison surveyed 635 dairy farms with robotic milking located mainly in the Midwest United States (Minnesota and Wisconsin), southern Ontario (between Detroit and Toronto), and lower Quebec (between Ottawa and Quebec City). The researchers (Tremblay et al., 2016) analyzed a data set including 54,065 observations collected from weekly observations over a 4-year period (2011–2014). In summary, average performance was:

• Milk production per cow: 32.7 kg/day
• Cows per robot: 50.5
• Milk production per robot: 1,666 kg/day
• Concentrate consumed in the robot: 5.18 kg/day
• Concentrate refused in the robot: 7.7%
• Milkings per cow: 2.9/day
• Minutes in the robot: 6.8/milking

Similarly, in the second study, Canadian researchers (King et al., 2016) analyzed a data set collected from 41 commercial dairy farms with robotic milking systems (26 Ontario/15 Alberta) from October 2014 to June 2015. These were the average robot and cow performance:

• Milk production per cow: 34.5 kg/day
• Cows per robot: 49.4
• Milk production per robot: 1,685 kg/day
• Milkings per cow: 3.0/day
• Involuntary milkings: 10.4%
• Fetched cows: 8.1%

In the third work conducted by University of Minnesota researchers (Siewert et al., 2018) included 33 dairies located in Minnesota and Wisconsin. These were the production data:

• Milk production per cow: 33.2 kg/day
• Cows per robot: 55.8
• Milk production per robot: 1,861 kg/day
• Concentrate consumed in the robot: 5.01 kg/day
• Concentrate refused in the robot: 0.27 kg/day
• Milkings per cow: 2.8/day
• Minutes in the robot: 7.5/milking

In addition, the authors in this study found that the amount of offered concentrate in the robot was positively associated with daily milk production. They stated that dairies feeding more concentrate generally were obtaining more milk per cow. Considering the results from these three experiments, we can indicate, that, on average, cows in robotic dairies are being milked 2.9 times per day and they are consuming 5.1 kg of concentrate (1.76 kg/visit). Since average milking time in the robot is 7.17 minutes per milking, concentrate eating rate is 0.26 kg/min.

Since cows are fed via a pelleted feed offered in the robot during milking, feeding cows in box robotic dairies is significantly more expensive than feeding a total mix ration (TMR) in conventional farms.

Concentrate supply

A recent survey conducted by University of Minnesota researchers evaluated management factors associated with cow performance in robotic dairies. The survey included 33 dairies located in Minnesota and Wisconsin, and the amount of concentrate offered in the robots averaged 5.01 ± 0.84 kg/cow. The authors (Siewert et al., 2018) found that the amount of concentrate offered in the robot was positively associated with daily milk yield, with farms offering more concentrate generally obtaining more milk production.

It has been suggested that providing a greater quantity of concentrate within the robot increases milking frequency. Three studies conducted in the Rayner Dairy Research and Teaching Facility at the University of Saskatchewan (Saskatoon, SK, Canada) evaluated the effects of the amount of concentrate offered on cow performance, intake and milking activity:

• In the first study, the authors (Hare et al., 2018) fed 2 diets: a high-energy TMR with 0.5 kg of concentrate in a dry matter (DM) basis provided in the robot or a low-energy TMR with 5.0 kg of concentrate consumed in the robot. Total DM intake was 2.7 kg greater for cows fed the high-energy TMR (26.3 kg; 0.5 kg concentrate + 25.7 kg TMR) than the low-energy TMR (23.6 kg; 5.0 kg concentrate + 18.6 kg TMR). Milking frequency was not affected by treatment with cows attending to the robot 3.0 times per day. Although milk production and milk composition were similar, cows receiving less concentrate in the robot gained more weight.
• In the second study, Menajovsky et al. (2018) evaluated the effects of the quantity of concentrate offered (2 vs. 6 kg) in both low- (54% forage) and high-forage diets (64% forage). Cows receiving more concentrate in the robot (6.1 vs. 2.0 kg/day) consumed less TMR in the feedbunk (21.4 vs. 24.9 kg/d); however, in this study total DM intake and milking frequency were not affected by treatment, averaging 27.3 kg/d and 3.6 times/d, respectively. Moreover, milk yield was similar (38.6 kg) regardless of concentrate supply in the robot or forage content in the diet.
• Finally, in the third study the researchers (Paddick et al., 2019) tested 4 concentrate amounts offered in the robot (0.50, 2.00, 3.49, and 4.93 kg of DM/day). Although intake of the TMR decreased linearly as the quantity of concentrate in the robot increased, total DMI intake was not affected by the amount of concentrated allocated in the robot, averaging 25.3 kg/d. Milking frequency (3.2 visits/d), milk yield (37.4 kg/d), milk fat (1.43 kg/d), and milk protein (1.22 kg/d) were not different among treatments.

The results of these works indicate that limiting the allocation of concentrate in the robot box does not affect cow intake, milk yield and milk components production, and voluntary attendance to the robot.

Applications

In conclusion, in robotic dairies, the concentrate should meet the following requirements: 1) be palatable so cows are motivated to enter the robot box; 2) have adequate presentation form (pellet or texturize) to maximize eating rate and reduce refusals, and 3) in combination with the feedbunk ration, it must supply nutrients to guarantee high production of milk and milk components.

by Fernando Diaz

β-galactomannans the multi-target solution against Salmonella

             

Salmonella infection is one of the most common food-borne illnesses in the world. Most human infections are food-borne and are caused by Salmonella Enteritidis and Salmonella Typhimurium.

Mannose- mode of action

Mannose is a monosaccharide with high binding specificity for Fim H adhesins of type I fimbriae on the surface of many Enterobacteria. Fimbriae are used by Enterobacteria to recognise mannose residues on glycoproteins of the intestinal epithelial cell surface. this is how these pathogens adhere to the intestinal wall as a previous and key step to penetrating enterocytes and invading the lymphoid tissue.

        Therefore, the use of mannose rich compounds prevents the bacterial ability to invade by blocking their fimbriae. However, it is not just the contents of mannose, but also the structure of the molecule, what determines the efficacy of these carbohydrates. For this reason, simple mannose monomers have low blocking capacity on bacterial fimbriae, and the resulting levels of intestinal tissue damage are similar to those of untreated animals. On the contrary, oligomannans (small to medium sized carbohydrates containing mannose) have been shown to be very efficient and have prebiotic proroperties which promote the gut flora and the competitive exclusion of pathogens.

            Salmosan is a source of vegetal β-galactomannans obtained after a technological process in which mannose long chains are fragmented by depolymerisation, neutralising thickening properties and maximising it Salmonella-blocking effect.

In Vitro Trials

               The efficacy of β-galactomannans against Salmonella was studied in vitro in different studies with intestinal cell cultures. These studies showed that, in the presence of β-galactomannans at 0.5 μg/mL, the invasion of intestinal cell by Salmonella Typhimurium added to the cell culture (4*10⁶CFU) was inhibited significantly about 60% versus the positive control (Figure 1).  In the presence of β-galactomannan levels of 10 μg/mL, the reduction was above 70%. 

        
      Salmonella remains blocked and is agglutinated by the hydrolysed β-galactomannans (Figure 2). The rugged, spherical structure of the β-galactomannans is seen clearly in this image; this struture facilitates the binding of bacteria to the molecules of mannose. The bacteria blocked by β-galactomannans are excreted in the faeces and have no infective capacity.

                                Figure 2: Electron microscope image of β-galactomannans
                                agglutinating Salmonella in chicken gut tissue.

In vivo Trials

Layers   

     Regarding in vivo efficacy, in a trial with 225 HyLine laying hens, animals were divided into two groups, a group fed with 500 g/ton β-galactomannans, and a control group. Twenty seven days after starting the treatment, animals were challenged with 10⁹ CFU of Salmonella enterica enterica Enteritidis (oral inoculation; 1 mL of suspension). Microbiological examination of caecum in the treated group showed that susceptibility to infection was lower than control baseline (6.3% vs. 25%). In addition, at four months post-inoculation, infected animals in the treated group no longer excreted the pathogens (Figure 3) and their tissues did not appear to be infected. This indicates that β-galactomannans at 500 g/ton are effective for the control of Salmonella in laying hens, reducing the percentage of positive animals.

Broilers
      In an experiment performed with broilers, 800 1-day males were divided into five experimental groups depending on the inclusion level of β-galactomannans in feed (0%, 0.05%, 0.1%, 0.15%, 0.2%), with 16 replicates/group. All of them were doubly inoculated (two consecutive days) with 1 x 10⁶ - 1.5 x 10⁶ CFU of Salmonella enterica enterica Enteritidis.
 
        It was observed that β-galactomannans reduced the isolation of Salmonella Enteritidis from caecum in a dose-dependent manner. With the higher inclusion level, the decrease in bacterial count was nearly three logarithmic units versus infected control (3.49 vs. 6.26) even just 14 days after inoculation (figure 4).

Conclusions:
    β-galactomannans block Enterobacteria such as Salmonella joining to their fimbriae, preventing them from invading the intestinal mucosa.
      β-galactomannans, at 500g/tonne, are effective for the control of Salmonella in laying hens, reducing the percentage of positive animals. In addition, at four months post-inoculation, infected animals in the treated group no longer excreted the pathogen and their tissues did not appear to be infected.
        In broilers, β-galactomannans (2 kg/ton) reduced bacterial counts nearly three logarithmic units versus infected control (3.49 vs. 6.26) even just 14 days after inoculation.
       

Early Breeding of Heifers May be Weighing You Down

                                 Yearling heifers. 

By Maureen Hanson

As an industry, we may need to rethink our strategy in pinpointing the ideal time to breed dairy heifers – again.

It wasn’t long ago that a new approach in breeding dairy heifers was popular. That strategy was to get heifers into the milking string absolutely as soon as possible, so they could stop costing money and start making money.

While well-intentioned and theoretically sound, veterinarian Gavin Staley believes it may have gone too far. Staley is a dairy reproduction specialist for Diamond V, and shared his thoughts on heifer breeding with the audience of the Dairy Calf and Heifer Association’s Annual Conference.

“Yes, it’s possible to get heifers pregnant to calve at 21 months,” said Staley. “But at this age, they would need to have had an average daily gain (ADG) of 2.05 pounds per day from birth to calving, to achieve the physical maturity necessary for optimal pregnancy and lactation.”

What’s really happening, said Staley, is that many herds are bringing heifers into the milking string at 21-22 months, even though they have grown at slower rates. He said heifers with an ADG of 1.81 pounds per day up to calving will not be optimally ready to hit lactation until 24 months of age, and those with ADGs of 1.75 pounds per day should not be calved until 25 months. “We are managing heifers to calve at 21 months and growing them to calve at 24 months,” said Staley. “That’s a serious disconnect.”

When first-lactation heifers calve too young for their physical maturity, they have a higher incidence of calving and transition problems, and need to continue channeling nutritional and metabolic resources to growth versus milk production. One pound of gain per day post-calving comes at a commensurate cost of about 7 pounds of milk per day. Staley said it’s a deficit they never overcome, even in their second and third lactations. “It’s the gift that keeps on giving,” he noted.

The veterinarian has observed evidence of this by examining data from hundreds of herds. In one analysis, he found that later-bred heifers (even just one month) gained 60 pounds more per head before becoming pregnant, and subsequently out-produced their earlier-bred herd mates by 3 to 4 pounds of milk per day in their first lactations.

“Over time, immature heifers become a ball and chain on the entire herd,” he stated. “Older cows are culled because they are pushed out by heifers entering the milking string, and pretty soon you’ve got a whole herd of lifetime underperformers. There is a single number that can be highly predictive of a herd’s average annual milk production, and that’s the 10-week milk production of lactation-1 heifers.”

Ironically, Staley said this phenomenon ultimately punishes the herds that do an excellent job of getting their heifers pregnant. “Good reproductive efficiency and immature animals are a toxic combination,” he declared.

The issue is further compounded by the use of sexed semen, which creates even more young replacements. In some cases, first-lactation heifers make up half or more of a herd’s total population. “It’s like having a bunch of college kids who never graduate,” said Staley. “You just keep paying the tuition, but they never get a salary.”

Staley shared data from one, 3,200-cow herd that delayed its age at first breeding by 40 days, ultimately pushing their first-calving age to about 24 months, instead of 22.5. The results: 7 more pounds of milk per head per day in their first lactations, and a 20% improvement in heifer conception rate. “In addition to achieving higher milk production, they were able to switch to sexed semen as a result of their improved reproductive success,” noted Staley. 

His advice for hitting the “sweet spot” in heifer-breeding maturity includes:

        1. Every dairy needs a scale. Heifers need to be weighed for both breeding readiness, and at freshening. The ultimate target is to freshen heifers at 85% of their mature weight (soon after/at freshening), or 95% of their mature weight at springing (DCC>260), to accommodate the additional weight of the calf and placenta.

        2. Base breeding decisions on weight and frame size, not age. Weight is the easiest factor to measure. The caveat is that heifers must not be overconditioned, as Staley noted it’s easy to make “butterballs.” Frame size – and not just height – is more challenging to evaluate, although new technologies are making it more practical to assess. Age can be used to breed heifers, BUT the dairy must be sure the heifer-raising process is delivering a mature heifer at that age. 

       3. Focus on heifer growth. Know your average daily gain, and use it to determine your ideal age at first breeding. Efforts to save costs in heifer-raising may impede growth and require later breeding ages. 

“Your ultimate goal should be to calve mature animals as early as you can,” advised Staley. “But it’s the lesser of the two evils to delay breeding.”