Antibiotic resistance has led poultry nutritionists to find alternatives for antibacterial growth promoters in broilers. Among these substitutes, one is mannan oligosaccharides (MOS), a yeast cell wall derived prebiotic. MOS decreases the load of pathogenic bacteria through 1) binding bacterial type-1 fimbriae 2) increasing goblet cells which produce bactericidal mucin and 3) providing favourable environment for the growth of beneficial bacteria leading to competitive exclusion. Balance between pathogenic and beneficial bacteria causes increase in villus length and decrease in crypt depth which are biomarkers for gut morphological improvement. As structure is equal to function, improvement in intestinal morphology increases activity of digestive enzymes and ultimately improves digestion. Besides these, immunomodulatory effect of MOS activates macrophages of gut associated lymphoid tissues resulting in improvement in cellular, humoral and cutaneous immunity. MOS also increases production of butyric acid and decrease pH of intestine in broilers. Though these combined mechanisms, MOS improves growth rate and performance of broilers.

Nowadays, there is an increasing concern for the public health about the consequences from the long and increased use of antibiotics in livestock production. The use of antibiotics in animal feed as growth promoters has been completely banned by the European Union since 2006, based on their possible negative effects on human and animal health. The removal of growth promoters has led to animal performance problems and a rise in the incidence of certain animal diseases. Thus, there is an urgent need to find alternatives to antibiotics, especially in EU. Due to the modern consumers' concern about the potential development of antibiotic-resistant bacteria as well as at the same time the need to prevent economic losses of the farmers, alternatives to antibiotics has been developed to prevent the health problems and to improve the growth performance in farm animals. Owing to the full ban of antibiotic use in EU there is an urgent need to find alternatives to in-feed antibiotics. New strategies and commercial products must be developed to improve animal health and performance, based on their safety, efficacy and cost-effectiveness. The aim of this study is to summarize the beneficial effects of currently used alternatives to in-feed antibiotics, i.e. probiotics, prebiotics, organic acids, phytogenic compounds and zeolites on health and growth performance in farm animals (swine, poultry and ruminants).

Respiratory diseases like infectious bronchitis virus (IBV) and avian metapneumovirus (aMPV) have been held accountable for major losses for poultry production. Nevertheless, scarce information was present dealing with the prevalence and molecular epidemiology of these infections in Greece and the efficacy of currently applied control strategies. To fill this gap, a specific epidemiological study was designed. A total of 106 broiler and layer farms, including 10 backyard and 96 commercial flocks, were sampled between March 2016 and May 2017, and the obtained tracheal swabs were tested for IBV and aMPV using RT-PCR based techniques followed by sequencing. For each farm, data regarding production type, flock features, clinical signs, and vaccination program were also recorded. Different associations between vaccination protocol, production type, animal category, birds density, age, presence of clinical signs, and IBV and/or aMPV infection were tested. Both IBV and aMPV field strain prevalence were proven high, approximately 20 and 30%, respectively, being the GI-19 lineage (14 out of 19; 73.6%) and B subtype (30 out of 30; 100%), the most commonly detected IBV and aMPV genetic types. Infection with IBV field strains was significantly associated with clinical sign presence (odds ratio = 8.55 [95CI = 2.17-42.90]). Remarkably, only the vaccination protocol involving a double vaccination at 1 D of age was proven protective against IBV-induced symptomatology, with the odds of developing disease being 4.14 [95CI = 1.34-14.51] times lower. No association was demonstrated between aMPV infection and clinical outbreaks or between aMPV and IBV detection, suggesting the marginal role of the former pathogen in poultry farming. Globally, the present study provides the first detailed investigation of the epidemiological scenario of 2 viruses traditionally considered of pivotal relevance in poultry farming and demonstrates that remarkable benefits could be obtained with just minor adjustments in vaccination protocols.

Infectious bronchitis (IB), caused by infectious bronchitis virus (IBV), account for severe economic losses in the poultry industry. The continuous emergence of a multitude of IBV variants poses many challenges for its diagnosis and control, and live attenuated vaccines, despite their routine use, still plays a significant role in driving IBV evolution, further complicating the epidemiological scenario. Unfortunately, the impact of different vaccination strategies on IB control, epidemiology, and diagnosis has rarely been investigated. This work presents the results of a large-scale diagnostic survey performed in Poland to study IBV molecular epidemiology and how vaccination may affect the viral circulation in the field. To this purpose, 589 samples were collected between May 2017 and January 2019, tested by reverse transcription-PCR for IBV and sequenced. Vaccine and field strains were discriminated based on genetic and anamnestic information. The most commonly detected lineages were 793B (79%) and variant 2 (17.4%), with sporadic detections of QX, Mass, and D274-like strains. Most of the detected strains had a vaccine origin: 46.3% matched one of the applied vaccines, while 36.5% were genetically related to vaccines not implemented in the respective protocol. Besides their practical value for the proper planning of vaccination protocols in Poland, these results suggest that only a fraction (17.2%) of the circulating strains are field ones, imposing a careful assessment of the actual IBV field menaces. Moreover, phenomena like vaccine spreading and persistence seem to occur commonly, stressing the need to further study the epidemiological consequences of the extensive use of live vaccines.

Infectious bursal disease virus (IBDV) is an immunosuppressive pathogen with a bi-segmented, double-stranded RNA genome. Two serotypes, named 1 and 2, are recognized, and serotype 1 is traditionally divided into classical, variant and very virulent strains. Despite having great practical relevance, this classification lacks standardization and may therefore generate confusion. The widespread adoption of molecular techniques, which do not allow to direct assess neither pathogenicity nor antigenicity, further complicates this scenario. Recently, two phylogeny-based classification methods have been proposed to obtain informative and standardized results. The first is based on the analysis of the capsid protein VP2 gene, considered as the main determinant of virulence, while the other one considers both VP2 and RNA polymerase VP1, located in different genome segments. The latter approach is therefore better suited to detect reassortment events, which play a significant role in IBDV evolution. This work reports the detection of eight strains in Portuguese broiler farms that diverged from all available IBDV sequences. Subsequent analyses of VP1 and VP2 sequences confirmed that these strains form a new genotype having segment A of a new genogroup and segment B of classical-like genogroup. No recombination events were identified, while several unique amino acid changes were found in key positions within the VP2. This discovery remarks the importance of a steady and attentive monitoring of IBDV epidemiology. Further research efforts will be devoted to characterizing the novel genotype, by isolating new strains, assessing their pathogenicity and determining the level of protection ensured by commonly administered IBDV vaccines.

Prevalence, Risks and Antibiotic Resistance of Salmonella in Poultry Production Chain | InTechOpen, Published on: 2017-04-05. Authors: Niki Mouttotou, Shakeel Ahmad, Zahid Kamran, et